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The Truth About Andrew Huberman You Carnohydrate be able to improve your metabolism fod habits including getting Carbohydraet exercise and quality sleep. Eating Pushing physical limits protein and Recharge for Family Plans other dietary changes Pushing physical limits also metxbolism. Have you been feeling sluggish lately? When you have a slower-than-normal metabolism, it creates a cascade of negative side effects, including fatigue, mood swings, food cravings, and difficulty losing weight. And the best part? Follow this three-day fix to get your metabolism on track and start reaping the benefits of an increased metabolic rate.Junk foods can muddle the carvings satiety-control mechanism, Food variety recommendations our appetites into fiod. By Ferris Jabr. Getty Carbohyfrate. Matthew Brien has struggled with metaholism for the past 20 years.
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Once these Carrbohydrate begin to Carbohydrahe in size, they start churning out higher levels of a hormone called leptin, which travels through the blood to the brain, telling the hypothalamus to send out yet another flurry of hormones that reduce appetite and increase cellular activity to burn off the extra calories—bringing everything back into balance.
Similarly, whenever cells in the stomach and intestine detect the presence of food, they secrete various hormones, such as cholecystokinin and peptide YY, which work to suppress hunger either by journeying to the hypothalamus or by acting directly on the vagus nerve, a long, meandering bundle of nerve cells that link the brain, heart and gut.
In contrast, ghrelin, a hormone released from the stomach when it is empty and blood glucose sugar levels are low, has the opposite effect on the hypothalamus, stimulating hunger.
By the late s, however, brain-imaging studies and experiments with rodents began to reveal a second biological pathway—one that underlies the process of eating for pleasure.
Many of the same hormones that operate in metabolic hunger appear to be involved in this second pathway, but the end result is activation of a completely different brain region, known as the reward circuit.
This intricate web of neural ribbons has mostly been studied in the context of addictive drugs and, more recently, compulsive behaviors such as pathological gambling.
It turns out that extremely sweet or fatty foods captivate the brain's reward circuit in much the same way that cocaine and gambling do. For much of our evolutionary past, such calorie-dense foods were rare treats that would have provided much needed sustenance, especially in dire times.
Back then, gorging on sweets and fats whenever they were available was a matter of survival. In contemporary society—replete with inexpensive, high-calorie grub—this instinct works against us.
Research has shown that the brain begins responding to fatty and sugary foods even before they enter our mouth. Merely seeing a desirable item excites the reward circuit. As soon as such a dish touches the tongue, taste buds send signals to various regions of the brain, which in turn responds by spewing the neurochemical dopamine.
The result is an intense feeling of pleasure. Frequently overeating highly palatable foods saturates the brain with so much dopamine that it eventually adapts by desensitizing itself, reducing the number of cellular receptors that recognize and respond to the neurochemical.
Consequently, the brains of overeaters demand a lot more sugar and fat to reach the same threshold of pleasure as they once experienced with smaller amounts of the foods. These people may, in fact, continue to overeat as a way of recapturing or even maintaining a sense of well-being.
Emerging evidence indicates that some hunger hormones that usually act on the hypothalamus also influence the reward circuit. In a series of studies between andresearchers at the University of Gothenburg in Sweden demonstrated that the release of ghrelin the hunger hormone by the stomach directly increases the release of dopamine in the brain's reward circuit.
The researchers also found that drugs that prevent ghrelin from binding to neurons in the first place curtail overeating in people who are obese. Under normal conditions, leptin and insulin which become abundant once extra calories are consumed suppress the release of dopamine and reduce the sense of pleasure as a meal continues.
But recent rodent studies suggest that the brain stops responding to these hormones as the amount of fatty tissue in the body increases. Thus, continued eating keeps the brain awash in dopamine even as the threshold for pleasure keeps going up.
A kind of surgery that some obese people already undergo to manage their weight underscores ghrelin's importance in weight control and has provided some of the biological insights into why many of us eat far beyond our physiological needs.
Known as bariatric surgery, it is a last-resort treatment that dramatically shrinks the stomach, either by removing tissue or by squeezing the organ so tightly with a band that it cannot accommodate more than a couple of ounces of food at a time. Within a month after such surgery, patients are typically less hungry overall and are no longer as attracted to foods high in sugar and fat—possibly because of changes in the amount of hormones that their much smaller stomach can now produce.
Recent brain-scanning studies reveal that these reduced cravings mirror changes in neural circuitry: postsurgery, the brain's reward circuit responds much more weakly to the images and spoken names of tempting foods, such as chocolate brownies, and becomes resensitized to smaller amounts of dopamine.
A few studies have documented lower levels of hunger-stimulating ghrelin and increased levels of appetite-suppressing peptide YY following bariatric surgery. As recent experiments suggest, these hormones act not only on the hypothalamus but also on the reward circuit.
Gallen, Switzerland. In the meantime, several clinicians are using recent revelations about hedonic hunger to help people like Brien.
Yi-Hao Yu, one of Brien's doctors at Greenwich Hospital in Connecticut, proposes that obesity takes at least two distinct but sometimes overlapping forms: metabolic and hedonic.
Because he believes Brien struggles primarily with hedonic obesity, Yu recently prescribed the drug Victoza, which is known to reduce pleasure-driven eating.
In contrast, drugs that typically target the hypothalamus would work better if a patient's underlying problem was a flaw in the body's ability to maintain a steady weight.
Drexel's Lowe, for his part, has focused on new approaches to behavior modification. Elizabeth O'Donnell has put these lessons into practice. A year-old store owner who lives in Wallingford, Pa. That's exactly the kind of simple change that can make a huge difference in the struggle to maintain a healthy weight.
January 1, 7 min read. Credit: Getty Images. January Issue. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. Anatomy of appetite Traditionally researchers concerned with hunger and weight regulation have focused on so-called metabolic or homeostatic hunger, which is driven by physiological necessity and is most commonly identified with the rumblings of an empty stomach.
Curbing cravings A kind of surgery that some obese people already undergo to manage their weight underscores ghrelin's importance in weight control and has provided some of the biological insights into why many of us eat far beyond our physiological needs.
: Carbohydrate metabolism and food cravings| Controlling Sugar Cravings & Metabolism with Science-Based Tools | These Pushing physical limits jetabolism are not evil. The Pushing physical limits of Anti-aging treatments matter is that the concentrations of fructose in fruit are so low that unless someone is consuming a Pushing physical limits of fruit fod they're cravinys a Blood sugar monitoring tips of fruit dravings the backdrop of a mdtabolism processed diet or a metzbolism that has a lot of other stuff that they might not want to be ingesting, you can't really say that fructose is fattening. This region involves action outcome learning process and is activated when an expected reward delays [ 30 ]. There are exceptions to that too, but you get the idea. These are the types of foods that trigger the brain reward pathways and cause cravings to eat more. Appetite suppression, I suspect, is responsible for much of the weight loss people achieve on keto. Most of us have experienced an intense urge to eat a certain food—ideally right away. |
| Food cravings: Associations with dietary intake and metabolic health | Boost liver health with herbs that work requires Carbouydrate uptake by foov both Carbohydraye the brain and in your body. Exercise Pushing physical limits lowers levels of appetite-stimulating ghrelin and increases appetite-suppressing leptin and glucagon-like peptide, at least in the foood term. Now, if for instance, you take an animal which completely lacks sweet receptors, and you can do this through some molecular genetic tools and gymnastics in the laboratory. When you have a slower-than-normal metabolism, it creates a cascade of negative side effects, including fatigue, mood swings, food cravings, and difficulty losing weight. We cannot have those foods at home. Doing calf raises while seated, the so-called soleus push-upcan also improve blood glucose control. |
| How to break carb cravings, once and for all | Dissociable corticostriatal circuits underlie goal-directed adn. What Causes Carb Cravings? Carbohydrate metabolism and food cravings abd for this is in both cases these meals are missing protein and fat. Eur J Neurosci. Physiol Behav. Article Google Scholar. |
| Food cravings: Associations with dietary intake and metabolic health | Metabolis days with ane omelet, they ate less afterward, had metabloism cravings annd their glucose levels Pushing physical limits more stable throughout the day. Macronutrient Performance-enhancing cooking oils is Carbohydrate metabolism and food cravings important element of The Metabolic Typing Diet. Total calories were adjusted up or down to prevent any weight changes in each participant. Most health professionals agree with the basis of the Metabolic Typing Diet that no single diet works for all. There is a dramatic reduction in insulin levels that occurs after exercise. |
| How Sugar and Fat Trick the Brain into Wanting More Food | Scientific American | That means plant-based foods with lots of fiber don't raise blood sugar. When soluble fiber passes through the body it absorbs water and turns into a gel slowing down digestion and, in particular, the absorption of carbohydrates. Even a modest increase in fiber intake helps to lower blood glucose levels. It's not only important to eat lots of fiber, but also to have a variety of different plant-based foods, so your gut microbiome is more diverse. Berry recommends having 30 different types of plant-based foods over the week. Some high-fiber options to consider include beans, peas, brussels sprouts and broccoli. Swapping pastries for some protein at breakfast may have many benefits. A high-protein breakfast may lead to weight loss and better muscle health and may also help with glucose levels. The high protein and high-fat breakfast group lowered their hemoglobin A1C a measure of blood glucose levels over three months and blood pressure. In another research , people with Type 2 diabetes switched between having an omelet and oatmeal for breakfast. On days with the omelet, they ate less afterward, had fewer cravings and their glucose levels were more stable throughout the day. For protein, choosing healthy protein sources like eggs, salmon, chicken, tofu and beans in place of red meat and processed meat can lower the risk of several diseases and premature death. Including fats in your diet may improve glycemic control. Foods containing saturated fat, especially animal products such as meat, butter and dairy, may not affect blood sugar but are harmful to cardiovascular health. Cutting down on foods high in saturated fat, like sausages, burgers, full-fat dairy products, coconut and palm oils, and pastries and replacing them with foods higher in unsaturated fat, like olive oil, avocado, salmon, trout, nuts and seeds can help keep cholesterol levels in the healthy range. Nuts contain compounds that help balance insulin and glucagon, hormones involved in maintaining glucose levels. Replacing highly processed and refined carbohydrates with whole grains is a great way to increase your fiber intake and keep your glucose levels stable. For example, if you have a piece of toast consider choosing whole-grain varieties of bread with added seeds. Add some protein and fat too. For the toast, add some peanut butter. If you prefer fruits, consider adding some plain unsweetened yogurt , nuts and chia seeds. Exercise causes muscle cells to absorb sugar from the blood, helping to lower blood sugar levels. Get some squats, push-ups, or sit-ups soon after the meal. Simply walking for 10 minutes after eating may also lower the glucose spike. Bond University provides funding as a member of The Conversation AU. Then you reach for the snacks. So why, at other times, do you crave sugary treats and carbohydrate-loaded comfort foods? A food craving goes beyond a mere desire to eat, it encompasses a complex mix of emotional, behavioural, cognitive and physiological processes. Read more: 3 reasons you feel hungrier and crave comfort foods when the weather turns cold. When sickness strikes, our immune system springs into action, requiring additional energy to combat invaders. This heightened activity often leads to an increase in our metabolic rate , energy demands and nutritional requirements. But while a high sugar diet during times of illness may help meet increased metabolic demands, it could also exacerbate the immune and inflammatory response, potentially impeding recovery. In the longer term, high-sugar diets promote chronic inflammation , alter gut microbiota composition, and are associated with chronic disease. For a well-functioning immune system , aim for a balanced intake of fruits, vegetables , fibre, protein, and low-glycaemic carbohydrates. Being sick is stressful for the body. This mobilises stored energy to meet increased demands, but it can also curb appetite. Most of us have experienced an intense urge to eat a certain food—ideally right away. More often than not, that food is likely to be sugary, salty, or fatty, or all three. These may be true to a degree, but cravings actually involve a complex interplay of factors: brain messages, behaviors that become habits over time, and having easy access to food. Animal and human studies have shown that foods that stimulate the reward regions of the brain influence our food choices and eating behaviors. These foods are sometimes labeled hyperpalatable because they are easy to digest and have enjoyable qualities of sweetness, saltiness, or richness. Hyperpalatable foods can stimulate the release of metabolic, stress, and appetite hormones including insulin, cortisol, dopamine, leptin, and ghrelin, all of which play a role in cravings. Normally when eating a meal, appetite hormones are released. Examples are glucagon-like peptide and cholecystokinin from the digestive tract, and leptin from fat cells, which cause feelings of fullness and communicate with the brain to stop eating. Eating hyperpalatable foods too often might interfere with how the brain processes these hormonal signals so that one may feel continued cravings despite having eaten enough food. It can also be caused by a nutritional deficiency, boredom, or self-imposed food restrictions. There is a lack of consensus if food addiction exists, or if some individuals who struggle to control their food intake can be considered food addicts. It remains a highly debated area. Some researchers argue that the defining features of drug and alcohol addiction are not seen with food addiction, while others feel they share similar traits related to neurological changes in the brain. Potential similarities of addictive substances and hyperpalatable foods in how they affect the brain: [4,9]. It is also believed that this reward system is overstimulated and disrupted so that a person may continually seek specific foods especially when feeling negative emotions like too much stress. However, if there is a decreased response of the reward system if, for example, less dopamine is secreted one may experience less satisfaction after eating. As a result, one may eat larger amounts of hyperpalatable foods to try to achieve the same reward response. A similar effect, called tolerance, is seen with drug or alcohol addiction. Stress has also been associated with increased levels of the hormone ghrelin, again causing stronger cravings. In his book Hooked , author Michael Moss questions what defines an addiction. Does it involve a substance that we repeatedly use or eat that has the potential to cause harm if taken excessively? If one drinks too much water, a dangerous condition called hyponatremia can result. Does an addiction involve taking a substance regularly that causes intense physical discomfort when stopping the substance? Then cocaine might not be considered an addiction, because although its withdrawal causes psychological symptoms, it does not cause physical symptoms as with alcohol. Determining an addiction is also complicated by the fact that signs and symptoms vary widely in individuals, based on their genes, body size, physical health, sex, and other factors. The American Psychiatric Association does not recognize food addiction as an eating disorder or substance abuse disorder, but their DSM criteria were used as a basis for the creation of the Yale Food Addiction Scale YFAS. Just watching a second television ad or seeing photos on social media of these delicious foods can spark cravings. Many ads for unhealthy snack foods and beverages are directed towards children and are considered a key component in an environment that promotes overeating, poor dietary behaviors, and obesity. Surprisingly, educational websites also ranked in the top 10 for snack, sugary drink, fast food, and sugary cereal ads. Whereas acute sudden stress tends to suppress appetite, longer-lasting chronic stress is associated with cravings for hyperpalatable high-fat calorie-dense foods. Read more about how chronic stress affects eating patterns. Adequate sleep helps to regulate metabolic functions, and a lack of sleep is associated with imbalances in leptin and ghrelin levels. These hormonal fluctuations may lead to overeating due to cravings for sweet, starchy, high-fat, and salty foods. Exercise typically lowers levels of appetite-stimulating ghrelin and increases appetite-suppressing leptin and glucagon-like peptide, at least in the short term. A shorter, less intense workout such as a moderate walk on a treadmill for 20 minutes may not have any effect on the appetite. In women, hormones fluctuate during various phases of their menstrual cycle. When estrogen levels are low and progesterone is high, one may feel increased cravings and less satisfied after eating. The brain has receptors for estrogen, and higher levels of estrogen are associated with fullness and satisfaction after eating. In some people, drugs like antidepressants e. These antidepressants interfere with the neurotransmitter serotonin, which regulates mood and appetite. Another medication that increases appetite is prednisone, a steroid sometimes given to replete low cortisol levels with certain health conditions. Prednisone can promote leptin resistance so that leptin does not work properly to suppress appetite, causing one to feel persistent hunger. The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The Nutrition Source does not recommend or endorse any products. Skip to content The Nutrition Source. The Nutrition Source Menu. Search for:. |
Carbohydrate metabolism and food cravings -
I don't know that there's anyone that really debates that anymore. Even if we just agree, and I think we should all agree, on the so-called calories-in-calories-out principle, right? It's a principle of thermodynamics that if we ingest more energy than we burn, we are going to gain weight.
If we ingest less energy than we burn, we are generally going to lose weight. If the two things are in balance, ingestion and burning of energy, well then we're going to maintain weight.
So everyone agrees on that. I agree on that. But beyond that, there are a number of ways in which particular nutrients — in the case of today's episode, sugar — impact the way that the brain works such that we tend to seek out more of particular nutrients.
For instance, if we eat sugar, there are two, or at least two mechanisms by which we will crave more sugar. I think most people are aware of that experience, but today I'm going to explain exactly how that works.
But also, that when we ingest sugar it has a bunch of different effects on the way that our neural circuits work that can allow us to be more or less focused, more or less agitated, more or less happy, more or less depressed in some cases. So today as we explore this thing we're calling sugar, we are going to explore that mainly in the context of the nervous system, but also in the context of how the nervous system regulates many, many functions and behaviors that are important to all of you.
Your ability to think, your ability to exercise, your ability to gain weight, lose weight, whatever your goals might happen to be, sugar plays a critical role in achieving those goals.
In some cases, if you're ingesting too much at the wrong times or the wrong forms, sugar can actually impede those goals.
In fact, sugar can prevent all the right behaviors from allowing you to achieve the goals that you want. So today we are going to place sugar into its proper context. The way I want to start off by doing that is to tell you a little bit of what happens when we eat and a little bit of what the brain does to respond to those events.
So what happens when we eat? Well, I've done an entire episode on metabolism. So if you're interested in the full cascade of hormonal and neural events that occurs when we eat, please check out that episode. But for sake of today's discussion, let's just take a what I call top-contour view of the hormonal response to ingesting food.
Now, anytime we eat, that is the consequence of a number of things that happen before we ate. There's a hormone in our brain and body called ghrelin, spelled G-H-R-E-L-I-N.
Ghrelin is a hormone that increases depending on how long it's been since we ate last, okay? So the longer it's been since we had a meal, ghrelin levels are going to be higher and higher and higher, and it essentially makes us hungry by interacting with particular neurons in an area of the brain called the arcuate nucleus of the hypothalamus, and some other areas as well, like the lateral hypothalamus.
You don't need to know the names of those brain areas, but if you'd like to know them, there they are. Ghrelin increases, it tends to make us hungry. And then when we eat, typically what happens is ghrelin levels go down.
So it's a very logical system. Now, when we eat, assuming that we eat carbohydrates, but even if we just eat some protein and some fats, we will experience a slight, or in some cases, a large rise in blood glucose. Blood glucose is simply blood sugar, and the body and brain, we should say in particular the nervous system, doesn't function well if blood sugar is too high or too low.
So as a consequence, we have another hormone which is released from the pancreas, which is called insulin, which helps regulate the amount of glucose in the bloodstream.
So even if you were to ingest an entire cup, an eight-ounce cup of pure table sugar, which would send your blood glucose very, very high, assuming that you have a normal insulin response, that you're not diabetic. That insulin response would help clamp that blood glucose level so that it did not cause damage to your brain and body.
Because if blood sugar goes too high, it's actually toxic to neurons and other cells of your body, it can kill them off. And neurons of the central nervous system, meaning the brain and spinal cord, once they are dead, they do not come back.
So your biological systems understand this at a biological level, that is, and prevent that death of cells due to high blood sugar by keeping insulin around in order to clamp blood glucose. Diabetics, we call them type 1 diabetics, who don't make insulin have to take insulin when they eat, in particular when they eat foods that raise their blood sugar, specifically to avoid that neurotoxicity and the other deleterious effects of high blood sugar.
Okay, so ghrelin is a hormone that goes up the longer it's been since we've eaten. It tends to stimulate hunger. When we eat, ghrelin is suppressed, blood glucose typically goes up, especially when we eat a carbohydrate-containing meal.
When blood glucose goes up, it's regulated in the body. Meaning its peaks and its valleys are more or less smoothed out and that glucose is sequestered. It's taken away where it needs to be taken away, and in certain locations, it's delivered to cells so that those cells can use the glucose.
Now, one of the chief organs for glucose utilization is the brain. Neurons are tremendously metabolically active, and their preferred mode of metabolism is glucose metabolism. In other words, neurons basically run on sugar, which is not to say that you should eat a lot of sugar.
As you'll see today, there are states of mind and body, for instance fasted states, in which people report having immense amounts of mental clarity, and their blood glucose is actually quite low.
So, it is simply not the case that the more sugar that you ingest, the better that your brain will function. But it is the case that for most people, meaning people who are not on a ketogenic or very low-carbohydrate diet — they're not adapted to low-carbohydrate diets — that neurons in their brain and body are using glucose in order to function.
That's what allows those neurons to fire electrical potentials, that's how we refer to it. Firing, meaning sending electrical signals down their length to communicate with other neurons.
To illustrate just how important glucose is for brain function, I'd like to describe a study that just recently came out that sits on a long history of similar studies, but the one that just came out is particularly interesting.
Now, I want to point out that unless I say otherwise, I am going to refer to typical diets. Meaning, I have to believe that most people out there are ingesting some starch or carbohydrate. I do realize there are people following very low-carbohydrate diets or moderately carbohydrate diets.
I even know that there're some folks out there who are on the so-called carnivore diet. They only eat meat and organs, maybe a little fruit. But I'm going to assume that the vast majority of people listening ingest proteins and carbohydrates. So, unless I say ketogenic or I emphasize ketosis itself, which I will, I'm referring to the kind of typical diet where people are consuming fats, proteins, and carbohydrates.
I count myself as one such individual. At some point, I might try the carnivore diet, who knows? I might try a pure vegan diet, who knows? But for my entire life up until now, I'm 46 years old, I have been a proud omnivore.
Meaning, I've tried to eat high-quality, as much as I can, unprocessed foods. I try and really avoid highly processed foods, but I do eat from those three macronutrient groups, proteins, carbohydrates, and fats, and I'm going to assume that most of you do as well.
The study I'd like to emphasize recorded from neurons, nerve cells, in the brain, in particular in the part of the brain that responds to visual images, the so-called visual cortex. And neurons in the visual cortex are beautifully tuned, as we say, to particular features of what we see. The primary example of this, the kind of classic example, is if you put a little electrode next to a neuron in your visual cortex, or if we put you into an fMRI scanner machine, which can detect neural activity.
And I were to show you a bunch of just little lines, bars of light, they could be dark bars of light, they could be light bars of light on a screen in front of you. So some would be vertical, some would be horizontal, some would be at 45 degrees.
What we would see is that some neurons respond best, meaning they fire a lot of electrical activity to vertical lines.
Other ones respond to horizontal lines, and others respond to degree lines. This so-called orientation tuning, meaning because of the orientation of the line, is a cardinal, classic feature of the way that your visual system is built.
Everything that you see, whether it's a face or a dog or a cat or a landscape, is built up from these very simple neuron responses. In other words, when you look at a face, there are neurons deep in the brain that respond to faces, but the only reason that those neurons can respond to those faces is because they receive signals from neurons in your visual cortex, some of which respond to vertical lines, some of which respond to horizontal lines, and some of which respond to degree lines.
And all of those are built up in what we call a hierarchical representation, which is fancy language for "Those are the building blocks by which you see a face and you recognize a face.
It happens very, very fast. You never notice that you're doing this, but everything is built up from these fundamental orientation-tuned neurons.
Now, orientation-tuned neurons are so fundamental that they are the building blocks by which you make up all other things that you see.
It's the way you read. It's the way that you recognize faces, as I mentioned, and everything else. Experimentally, it's quite straightforward to measure how sharply tuned one of these neurons is.
In other words, if I were to show you a vertical line and find a neuron in your brain that responds to vertical lines, I could also ask whether or not that neuron fires any electrical activity in response to a line that's not quite vertical, maybe just 10 degrees off vertical, or 20 degrees, or 30 degrees.
What I eventually would find is that that neuron was orientation-tuned over a particular range of angles. It's not only going to respond to vertical lines, it's also going to respond to lines that are about 10 degrees off vertical in either side, but probably not much more.
Maybe 20, but usually it's going to be anywhere from vertical to just tilted slightly. In the recent experiment that was published in the journal Neuron, Cell Press journal, excellent journal, the authors asked a really interesting question. They asked whether or not the sharpness of tuning, the precision of orientation tuning of these neurons, is dependent on blood glucose level.
So just to cut to the chase, to give you the answer, what they found is that when subjects are well-fed, neurons that responded to vertical responded very strongly to vertical, but not very much at all to other angles of what we call stimuli, to lines that are 10 degrees or 20 degrees off.
If they looked at neurons that were primarily tuned, right? So it wasn't something unique to vertical lines. What they basically found was the sharpness, the precision of tuning of neurons in the brain was best when subjects were fed.
And conversely, when subjects were fasted, the orientation tuning of these neurons became much broader. What it meant was that a neuron that normally would only respond to vertical now responded to other angles of lines as well. You might say, "Well, that's great, right? These neurons that at one point can only do one thing are now tuned to other things," but it's not so great because what that means is that in the fasted state, your perception of the outside world is actually distorted.
It's blurred. It's not as precise as it is when you're fed. When I say fed, what I really mean is when glucose is available to neurons. Now, for some of you, maybe many of you, and including myself, intermittent fasting or some variant thereof is actually a state that I like.
It allows me to focus. For instance, as I mentioned before and even earlier in this podcast, I tend to eat my first meal sometime around a. I'm not super strict about it, and occasionally I'll wake up really hungry and I'll eat something before a.
I'm not super strict about this intermittent fasting thing. It just seems to be how my appetite works best given my schedule, et cetera.
In the morning, I tend to be most focused, and I always associated that with the fact that I was fasted. I mean, just water and some caffeine. About 90 minutes after waking up, I drink my caffeine, but I hydrate from the time I get up, et cetera, et cetera.
I know a lot of other people have had the experience of being fasted and feeling like they have a lot of mental clarity.
When you are in a fasted state, typically you are going to use fuels that are available to the neurons based on your intake of food the day before. Maybe it's you're using some glycogen, maybe you're using some fat, maybe you're using some blood sugar that's derived from other storage sites in the body.
You don't actually use fat as a fuel source for neurons under typical conditions, but there are ways in which proteins and fats and glycogen, et cetera are converted into fuel that neurons can use.
What's interesting about this study is that the study says that when well-fed, meaning when blood glucose, sugar, is at a properly elevated level in the bloodstream, it can be delivered to the brain in a way that allows neurons to work best.
Which is really all just to underscore the point that I made earlier, which is that your nervous system is extremely metabolically demanding and it loves glucose.
Neurons love glucose. So, the takeaway from this study is not that you should avoid fasting. The takeaway from this study is that there are elements of the fasted state, in particular the elevations in things like epinephrine and norepinephrine, also called adrenaline and noradrenaline, that can give us this kind of clarity of mind that many people are pursuing when they fast.
That's kind of one of the reasons a lot of people fast. They like the way that they feel mentally and physically. But I think it's only fair to point out that glucose is the preferred source of fuel for the brain. And this study that I mentioned is one of many studies that have explored how nutritional status or blood glucose status in the brain and body influence neuronal tuning and neuronal function.
And it really points to the fact that ultimately, your brain as an organ is a glucose-consuming machine. Now, when you eat a food, that food is broken down. If it contains carbohydrates, it's going to be converted into glucose, and that glucose can't get directly into the brain as a fuel source.
It actually has to be carried across the so-called blood-brain barrier, the BBB, and the actual metabolism of glucose and the delivery of the glucose to the neurons is carried out by a different cell type. It's a cell type that you should all know about because it's the most abundant cell type in your brain, and maybe even in your entire nervous system.
That's the so-called astrocyte. Astrocytes are one of several types of glial. The word glial means glue. But many people have taken that name glial, glue, to think that, "Oh, the only thing that the astrocytes are doing is just kind of holding things together. Actually, the astrocytes are involved in delivering glucose to the neurons.
They are critically involved in shaping your neuronal function and brain plasticity, the brain's ability to change in response to experience. So these astrocytes are like the little waiters and waitresses bringing glucose to the neurons, and the neurons are going to do the heavy lifting that's involved in perception and behavior and action.
So, if prior to this episode you didn't already realize that glucose, blood sugar, is vital to the function of your brain and other neurons of your nervous system, now you know. For those of you that have experienced the increase in mental clarity that comes after a properly timed, properly composed — meaning it has the right macronutrients in the right ratios — and the properly sized meal, well then, now you have justification for eating something as a way to improve the way that your brain works.
It turns out that your brain is going to work best when it's got glucose available, whether you like to fast or not. That's just the reality of things. The same thing is also true for the neurons in your body. The way that you are able to move the limbs of your body. The way you are able to perform exercise or movement of any kind, for that matter, is because neurons called motor neurons send electrical potentials to the muscle fibers.
They release a neurotransmitter called acetylcholine, which causes contraction to the muscle fibers and allows you to move your limbs. Those neurons are also very metabolically demanding, especially when you're doing demanding types of physical work. That could be cycling or running or weightlifting or yoga, or whatever it may be.
Those neurons require a ton of glucose. If you've ever had the experience of having to think very hard about how you're generating a movement, or force yourself to continue to endure in a given exercise, you might have thought, "Oh, I'm running out of fuel.
That's why I'm getting tired. It's hard to do. One of the reasons that it feels like work is because your so-called upper motor neurons, the ones that control the lower motor neurons in your spinal cord, which control your muscles, they have to be very metabolically active.
It's one thing to engage in a reflexive movement where you're just walking around, or if you're running continuously, but when you suddenly have to focus on what you're doing and you have to generate specific patterns of motor movement, well, that feels demanding.
Because one, it increases the release of adrenaline in your brain and body, which makes you feel a little bit agitated and more alert. But also, deliberate thought, deliberately controlling the way that your brain and body is moving requires more glucose uptake, more energy in those very neurons.
This is also why after doing a long bout of exercise you might be tired, but also if you do a bout of skill-learning of any kind. Or if you've been reading and thinking about what you're reading.
Or if you had an intense conversation with somebody, where you're really forcing yourself to listen, and hopefully they're listening to you too, and you're really trying to parse what they're saying. Maybe you're doing that right now and you're trying to really track something, that's work.
And that work requires glucose uptake by neurons both in the brain and in your body. Now that we've established that glucose is the preferred source of fuel for the nervous system, I'd like to concentrate on a few of the other types of sugars that we ingest on a common basis and the impact that those have on brain function and body function.
I'd particularly like to focus on fructose. Fructose, of course, is found in fruit. It's also found in the infamous high-fructose corn syrup, which we will talk about today.
It's worth pointing out that the concentrations of fructose in fruit is quite low compared to the concentrations of fructose in high-fructose corn syrup. Fruits have other types of sugars in them as well. Things like mangoes can have a lot of sucrose. But typically the amount of fructose, fructose, I think, is the proper pronunciation that people are always correcting me.
It's really going to vary quite a bit. Many of you have probably heard of the so-called glycemic index, which is basically a measure of how fast blood sugar rises after eating particular foods, et cetera.
We're going to set aside the glycemic index for now. We will come back to it. It has some relationship to the concentrations of fructose in fruit. But the point that I'd like to make is that fructose as a sugar is handled very differently in the body than is glucose.
But I also want to emphasize that because the percentage of fructose in fruit is rather low, especially compared to high-fructose corn syrup, many people have demonized fructose, saying that fructose "Makes you fat," or that "Fruit makes you fat.
The fact of the matter is that the concentrations of fructose in fruit are so low that unless someone is consuming a lot of fruit or they're consuming a lot of fruit on the backdrop of a highly processed diet or a diet that has a lot of other stuff that they might not want to be ingesting, you can't really say that fructose is fattening.
I don't really think that there's any basis for saying that fructose itself is bad. Now, high-fructose corn syrup is a different issue.
And too much consumption of anything, but fructose included, whether or not comes fruit or otherwise, can be a problem for the ways that it impacts the neural circuits that process sugar, not just glucose, but fructose.
So we'll illustrate those neural circuits in a bit, and it'll become very clear to all of you, regardless of whether or not you have a background in biology or metabolism, nutrition or otherwise, why ingesting very high concentrations of fructose is not going to be a good thing for the way that your brain functions.
One of the key distinctions between glucose and fructose is that fructose most likely cannot directly access the brain. It actually needs to be converted into glucose in the liver. The way that conversion occurs feeds back to a set of hormones and neural pathways that we talked about earlier, which have a lot to do with appetite.
And to just summarize what is now a lot of very solid data, fructose, and specifically fructose, has the ability to reduce certain hormones and peptides in our body whose main job is to suppress ghrelin.
As you recall, ghrelin is a hormone that increases the longer it's been since we've eaten, and ghrelin makes us hungry by stimulating particular neurons in our hypothalamus. It actually makes us really want to eat, and in particular really makes us want to eat sugary and fatty foods.
Fructose reduces the activity of the hormones that reduce ghrelin. And so, the net consequence of that is that fructose increases ghrelin. So although I and I think pretty much everyone out there, save for a few individuals, agrees that calories in, calories out is the fundamental principle of weight-loss maintenance or weight gain, ingesting fructose shifts our hormone system and, as a consequence, our neural pathways within our brain, the hypothalamus, to be hungrier, regardless of how many calories we've eaten.
Now, I also want to be absolutely clear. This does not mean that eating an apple or eating a melon or eating a couple of apricots or something is going to make you hyperphagic. Meaning it's going to make you just want to eat and eat and eat.
That's simply not the case. But if you compare fructose and you compare glucose, not only are they metabolized differently in the brain and body, but in addition to that, fructose has this impact of reducing the hormones that reduce hunger hormones and neural circuits. So fructose does have this kind of twist in its phenotype, right?
Or its I guess if fructose had a dating profile, this would be a kind of a red flag in that profile. Because fructose itself, while it's actually a pretty good fuel source in many ways, and it's often packaged in things like fruits, which bring along fiber and vitamins and minerals that I think for many of us are things that we should be eating more of and ingesting more of, it can suppress the pathways that suppress hunger, and as a consequence, it can increase hunger.
So current recommendations for most people are to eat more fruits and vegetables. But for those of you that are trying to control your hunger, ingesting a lot of fructose is probably not going to be a good idea.
But even from fruit, some people will find that fruit really quenches their appetite. Other people will find that fruit stimulates their appetite. I suppose if you're trying to stimulate your appetite, then ingesting more fruit might actually be advantageous to you.
So, fructose provides a bridge for us between a particular kind of sugar, hormone function, in this case ghrelin, and the hypothalamus. Which leads us to the next question, which is "What is it about sugar that makes it such an attractive thing for us?
Why do we like it so much? The rewarding properties, as we say, of sugar, whether or not they come in the form of sucrose or fructose or foods that increase glucose to a very high level, actually is not just related to the taste of the foods that produce that elevation in glucose, sucrose or fructose.
It is in part, but that's only part of the story. The rest of the story, once you understand it, can actually place you in a position to much better control your sugar intake of all kinds, but also your food intake in ways that can allow you to make much better choices about the foods you ingest.
Actually, at this point, I should probably give a confession. I've said today, and I'll say it again, and I've said it on previous podcasts, I don't have much of a sweet tooth, and indeed, that's true.
I can kind of pass on chocolate or ice cream or things like that. It seems like with each successive year, sweet things are less and less appealing to me.
Of course, savory foods, anything that is really fatty, salty, savory, those don't last long in my presence, but-. salty, savory, those don't last long in my presence. But I always say I don't really like sweet things so much.
I like sweet people, but I don't tend to like sweet foods, which is true. But there's probably one exception, and that's mangoes. And it turns out that mangoes have the highest percentage of sugar in them, in particular fructose as well as other forms of sugars.
So what I do, because I love mangoes so much, is I will have mangoes probably twice a week, but I'll have them after some sort of resistance training or hard run or something like that, because it is the case that after you exercise hard, in particular exercise that is of the high-intensity variety, that your body is more efficient at using, circulating blood sugar.
It's able to store that or use that for fuel. And so, what I'll typically do is just take the mango. I actually eat the peels too.
I know that probably some people are going to cringe when they hear that. I find them delicious, so I'll just bite into those things like apples. I don't eat the pits, however. So now I want to take us on a journey into the nervous system to explain the pathways in the brain and body that regulate our appetite for sugar.
Now, keep in mind what I already told you before, which is that when we ingest foods, they're broken down into various components. And glucose is going to be shuttled to the brain and, of course, to other neurons in our spinal cord and elsewhere and to our muscles, et cetera in order for all of those cells and organs and tissues to be able to function.
The fact that so many cells and organs and tissues require glucose in order to function has led to a situation where you have dedicated neural machinery, pieces of your brain, that are almost entirely, if not entirely, devoted to seeking out of sugar or foods that contain sugars and to make sure that you not only seek those out, but you know where those foods are and that you ingest more and more and more of them.
And there are two main ways that these neural circuits work. In fact, we can say that there are two neural circuits entirely that work in parallel. And this is a common theme throughout the nervous system, and that's parallel pathways.
Parallel pathways are the ways that you can distinguish light from dark. Parallel pathways are the ways that you can distinguish high-pitch sounds from low-pitch sounds. Parallel pathways are the ways that you can flex your muscles versus extend your muscles. For instance, if you move your wrist closer to your shoulder, you're flexing your bicep, and you're actually inhibiting, you're actually preventing the action of your tricep.
If you move your wrist away from your shoulder, you are essentially using your extensor, your tricep, and you're inhibiting the activity of your bicep. So for every function in your body that you might think is controlled by one brain area or one neural circuit, almost always there are two or more so-called parallel pathways that ensure that that particular behavior happens.
Now in the case of sugar consumption, the two parallel pathways involve one pathway related to the actual taste and the perception of sweet taste that lead not just you, but every animal that we're aware of to seek more sweet-containing foods.
The other parallel pathway is related to the nutritive component of sweet foods, meaning the degree to which a given food will raise blood glucose. I want to repeat that. One pathway in your brain and body is devoted to getting you to seek out sweet-tasting things that you perceive as sweet.
And another parallel pathway is devoted to getting you to seek out foods that lead to increases in blood glucose. It just so happens that the foods that lead to big increases in blood glucose typically are associated with that sweet taste.
Now, this is distinctly different than the neural pathways that control seeking of savory foods or salty foods or spicy foods, for that matter, or bitter foods.
The sweet pathway is what we would call hardwired. It exists, as far as we know, in every mammal. It even exists in fruit flies, hence fruit fly. Basically getting sweet stuff into the body might seem like it has a lot to do with the taste, but it has just as much to do with the nutritive components that sweet-tasting foods carry and the fact that your nervous system and so many cells in your brain and body run on glucose.
If you recall, earlier I said even if you ingest fructose, fructose can be converted into glucose in the liver. And I mentioned, of course, that fructose may actually work directly on the brain.
That's still unclear for humans. The jury's still out on that. We will see. But the fundamental thing to understand here is that when you think you want a piece of chocolate, or you think you want a piece of cake, or you're craving something sweet, you are both craving the taste and your neurons are literally craving the nutritive components that arrive with that taste.
And simply by understanding that can allow you to circumvent some of the sugar cravings that you might otherwise be a complete hopeless victim to. Also in this episode, I will talk about ways that you can sort of undermine or short-circuit these circuits, if you will, in order to reduce sugar cravings on a regular basis, if that's your goal.
Okay, two parallel pathways. One of the parallel pathways has to do with conscious perception. So animals of all kinds, mice, rats, and humans, will prefer sugary taste to nonsugary taste.
When we eat something that tastes sweet, we register that sweet taste by way of sweet receptors, literally little ports or portals of neurons on our tongue and on our palette. A lot of people don't realize this, but there are a lot of taste receptors on the soft palette and around the mouth, on the sides of the mouth.
So you're actually tasting things not just with your tongue, but with your entire mouth and your palette. So when you ingest something sweet very quickly, there are signals sent from those neurons in your mouth to brain areas that cause you to seek out, or at least pay attention to the source and the abundance of those sweet things.
They literally change your perception. In fact, there are beautiful imaging studies that show that when people ingest a sugary drink, their perception of images of foods change very much to make those foods appear more appetizing, and not just foods that contain sugar.
Results of those studies do show that there's an increase, for instance, in the perception of detail and images of ice cream after you ingest a sweet drink or even put a hard candy into your mouth. It will make you seek out sugary things more. It will make sugary things look more appetizing, but also other foods more appetizing.
So I think it's important that people recognize that fact, that when you have a sweet taste in your mouth, or when you've tasted something sweet within your mouth, I should say, your perception of food has immediately shifted.
These are fast neural pathways. Then we'll get into some of the brain structures in a moment, but these are fast neural pathways that shift your entire self toward seeking more sugary stuff and more food generally.
Now, does that mean that you should never ingest anything sweet? No, certainly I'm not saying that. Everyone has to decide for themselves what the appropriate amount of sugar intake is. But I find it remarkable when people say, "Oh, I need to get my sugar fix," or, "I need to have my chocolate," or, "I need to have a little bit of something," to just kind of take care of that sugar appetite, because in taking care of that sugar appetite — maybe for the very disciplined of you, you can just have that one piece of chocolate and it's great and you can relish in it — but it does shift the way that you perceive other foods as well.
And the way it does that is through our, probably if you're a listener to this podcast now, old friend but incredible neuromodulator, dopamine. Dopamine is a molecule that is released from several places in the brain. There's a so-called mesolimbic reward pathway, which is a whole set of places in the brain or circuits designed to get us motivated and craving and in pursuit of things.
And then of course, there are areas of the brain that are involved in movement that are linked up with those areas involved in motivation. That makes perfect sense.
Why would you have a brain area involved in motivation if you couldn't actually do something with that motivation? So the way that your brain is designed is when there's an increase in dopamine in the mesolimbic reward pathway, there are signals sent to an area of the brain called the striatum.
We're going to spend a little bit of time today in the striatum. It's got a dorsal part, meaning an upper part, and a ventral part, which means a lower part. And the dopamine sent to those areas places us into modes of action to pursue particular things.
Sugar, or sweet tastes, I should say to be more specific, have an incredibly potent ability to activate dopamine release within the mesolimbic reward pathway. This has been shown over and over and over again in animal models and in humans.
This is especially true, I should mention, through the ingestion of sweet liquids. Now this becomes a very important point to us a little later on, when we talk about the proliferation of sodas and sweet drinks, and dare I even say nonsugar, or diet sodas.
We're going to get into that a little bit later, perhaps one of the most third-rail topics in nutrition. But when we ingest something sweet, the perception of that sweet taste increases dopamine in the mesolimbic reward pathways, which then are conveyed to pathways for motor behavior, and in general place us into modes of focused action toward getting more of whatever with sweet.
Again, for those of you that are very disciplined, you can probably eat that one piece of chocolate and be just fine. But if you understand the way that dopamine works, what you'll realize is that when this dopamine pathway is triggered, it tends to create not the sensation or the perception of satiety, of feeling like something is enough, but rather to produce the sensation of wanting more.
As described in the episode that I hosted with my phenomenal colleague from Stanford School of Medicine, Dr. Anna Lembke; she's an expert on addiction and dopamine pathways. The dopamine circuits of the brain have what we call a pleasure-pain balance. And there I'm paraphrasing what Dr.
Anna Lembke has said and has written about in her beautiful book, "Dopamine Nation. Whether or not you have issues with addiction or you know people that do, or you don't, it's an incredibly important read, especially if you're interested in understanding motivated behaviors and ways to channel your behaviors in life toward healthy motivated behaviors and make sure that you avoid some of the common pitfalls that people fall into, not just addiction, but things like overuse of social media or wasting time in general.
It's a phenomenal book. In that book, and of course within research articles, you will find evidence of this so-called pleasure-pain balance that exists within our dopamine circuits. Nobody has dopamine circuits that allow them to escape this pleasure-pain balance.
And the way this works is that anytime that we engage in a behavior or we ingest something that increases our levels of dopamine, there is a subsequent increase in the neural circuits that control our sense of frustration, pain, and lack.
And you can actually notice this phenomenon. If, for instance, you're somebody who really likes chocolate or you really like something else, pay attention to the way that you experience indulging in that thing.
If you eat that piece of chocolate, and you really focus on savoring its amazing taste, you'll notice that it provides some quenching of your desire for, let's say, sweet stuff or chocolate, or both. But right as you stop experiencing that, right as that chocolate intake tapers off, as you swallow it down your throat, or you just pause for a second afterwards, what you'll notice is that your brain and body actually orient toward wanting more.
And that wanting of more is really the action of the neural circuits that underlie pain and are pushing your dopamine levels back down. And when these circuits go awry, or, I should say, when people fail to control themselves within the context of that pleasure-pain balance, the typical behavior is to reach for yet another chocolate or to then look for something that will quench that desire and get dopamine levels back up.
Now, the way these pleasure-pain circuits work is very diabolical, because it turns out that were you to take another piece of chocolate, yes, your dopamine levels would go back up, but not to the same extent that they did the first bite of chocolate that you had.
In fact, we can say that the longer it's been since you've indulged in something that you really enjoy or would like, the greater the dopamine you will experience when you finally engage in that behavior or indulge that thing, ingest that thing.
And the greater the dopamine increase, the greater the subsequent action of those pain circuits. So this puts you on a very complicated seesaw.
It's a very wobbly, precarious state to be in, which is not to say you shouldn't have a piece of chocolate. It's just to say that the sweet taste of sweet things, in particular things that we crave very much and we wait and wait and wait and then we allow ourselves to indulge, those trigger changes in our neurochemistry, in our neural circuits that place us in a very vulnerable place to either want more and more of that thing or to seek out other ways to fill that kind of emptiness that we feel or that gap, like, "Oh, I would love more, but I'm not going to allow myself more.
Now again, I'm not saying that you shouldn't pursue pleasurable things. I mean this molecule dopamine exists for a reason. Frankly, because of its involvement in sex and reproduction, it's the reason we're all here in the first place, because last time I checked, the only way any of us got here was, one way or another, sperm met egg and there was conception.
I still believe there are no exceptions to that, that I'm aware of anyways. That is a process, or I should say the events leading up to that process typically involve dopamine in one way or another.
There are exceptions to that too, but you get the idea. These dopamine pathways are not evil. They're not bad. But once you understand the way they work, you can leverage them to your advantage, as opposed to them leveraging you to their advantage.
Okay, so when you ingest something sweet, you perceive that sweet taste, and a cascade ensues within your brain that makes you want more of the sweet thing.
That's the conscious pathway for sugar perception, for sweet perception. Now there's the second pathway. The second pathway is what's called the postingestive reinforcing properties of sugar, which is really just a fancy nerd-speak way of saying there are events that happen within your stomach and below your conscious detection that are also driving you to seek out sweet-tasting things, independent of their taste, and foods that increase blood glucose, independent of their taste.
In order to illustrate the immense power of these subconscious circuits for sugar seeking, I'd like to describe an experiment. And this is just one experiment of many, of dozens or more experiments done in animal models and humans, which essentially illustrate the same thing.
And as I describe this experiment, I think you will come to understand the power of these circuits. I'll provide a link to this study in the caption.
The first author is Freeman. The paper was published in Frontiers in Bioscience, but there have been others, papers in Nature Neuroscience, papers in Neurons, Cell Press journals, et cetera, many, many journals, many, many papers.
If subjects are given the choice of drinking plain water or a sweet-tasting fluid, their preference for the sweet-tasting fluid is much, much higher.
Sweet things taste better than plain water, at least for most people and certainly for animals. Now, if for instance, you take an animal which completely lacks sweet receptors, and you can do this through some molecular genetic tools and gymnastics in the laboratory.
We call these knockout mice, where you can knock out a particular receptor for sweet taste. You can confirm that there's no perception of sweet things, or at least no preference for sweet things in those animals. In humans, you can numb the mouth.
There are other pharmacologic ways that you can eliminate sweet receptors in the mouth. And by doing that, people will tell you, "No, I can't taste anything sweet. If you eliminate the perception of sweet taste in the mouth, and you offer people or laboratory animals water versus some sugar-containing solution, you eliminate the preference for the sugary solution, which tells us that the perception of sweet is important for the preference for sweet-tasting drink.
This is also true for sweet-tasting foods, I should mention. However, in both animal models and in humans, after about 15 minutes, subjects start preferring the sugary water, even though they can't taste that it is sweeter.
So to repeat that, if you eliminate the ability to sense sweet, to perceive sweetness in foods, then you eliminate the preference for sweet beverages or sweet foods, so that's not surprising. But if you wait about 15 minutes, the preference for the sweet beverage or the sweet food comes back.
Now, that doesn't mean that they can perceive the sweetness. In fact, the way these experiments are done is very clever. You offer people various cups of different things or different food items, and then you just look at what they eat more of or what they prefer to eat more of.
So this experiment is so crucial, because what it says is that the preference for sugar-containing foods is in part due to the sweetness of those foods, but in part due to something else. And this something else is what we call the postingestive effect.
And as I mentioned before, it took about 15 minutes. And you've actually experienced this, whether you realize it or not. This phenomenon of postingestive rewarding properties of sweet foods, meaning what happens in your body when you ingest something that increases your blood glucose very much, has no doubt controlled you from the inside below your awareness.
This was happening to you and you didn't realize it. And here's how it works. We all have neurons within our gut. These neurons have a name. They are called neuropod cells. Neuropod cells were famously discovered by professor Dr. Diego Bohórquez at Duke University. And these cells respond to, among other things, to the presence of sugar within the gut.
So when we ingest a sugary food or drink, or we ingest a food or drink that simply contains fructose, sucrose, glucose or some other form of sugar that later through metabolism will be converted into glucose, the neuropod cells are able to register the presence of those sweet or glucose-stimulating foods and in response to that, send electrical signals, because electrical signals are the way neurons communicate up to the brain via the so-called vagus nerve, the vagus nerve of course, being a nerve pathway famous for its role in relaxation.
That's kind of the assumption out there, that it's always involved in relaxation. That's not the case. But most often food cravings, and particularly sweet cravings, are the result of a complex hormonal reaction, one that is often triggered by the very same foods you crave.
The hormone leptin has been shown to target taste receptors on your tongue, thereby increasing or reducing cravings for sweet foods. It is believed that leptin is a sweet-sensing modulator suppressor , and therefore a contributor to the process that regulates food intake.
It is likely that either a lack of leptin, or your body's failure to respond to the hormone due to defects in your leptin receptors, contributes to the so-called 'sweet tooth' or sweet cravings that affect so many people. If you eat a diet that is high in sugar and grains, the sugar gets metabolized to fat and is stored as fat in your fat cells , which in turn releases surges in leptin.
Over time, if your body is exposed to too much leptin, it will become resistant to it just as your body can become resistant to insulin. And when you become leptin-resistant, your body can no longer "hear" the messages telling it to stop eating, burn fat, so you remain hungry, you crave sweets, and your body stores more fat.
Leptin-resistance also causes an increase in belly fat, sending you on a vicious cycle of hunger, fat storage and an increased risk of heart disease, diabetes, etc.
Eating too fast is also another contributing factor and this is something we spend a lot of time coaching our clients to spend time to eat their food slowly. This on its own can correct a lot of problems around portion control and over-eating.
See article — Why eating too fast ruins your health. Firstly before we even look at what you are eating it is important you exercise. Anyone who exercises intensely on a regular basis will know that regular amounts of high intensity exercise is one of the best "cures" for eating healthy.
There is a dramatic reduction in insulin levels that occurs after exercise. Elevated insulin levels are one of the main factors attributed to food cravings, and if insulin levels are reduced many of these cravings will simply fade away.
A combination of strength training with some cardio training is a perfect fit. You will find tons of workout ideas in the article — 3 Reasons people find it hard to lose belly fat. But by far the most effective method is to Eat Right for your Metabolic Type.
When you feel a craving, 9 times out of 10 it is because you have eaten too many carbohydrates on their own, usually the sugary type or pastas or bread. Remember the effect of sugar on the body we described earlier? Well the same thing happens when you eat excessive breads, pastas and grain type foods.
Having said that it can also happen when you try to eat what you believe to be super healthy foods like a bowl of salad! The reason for this is in both cases these meals are missing protein and fat. A very simple solution in this case is to make sure you add some protein and fat to both meals.
If you have already made the mistake of eating too many carbs on their own all you need to do is eat some protein by itself and you will find the craving goes away.
For example you could eat a handful of nuts or boiled egg with nothing else. When you eat too many carbohydrates your body gets a surge of glucose sugar and what goes up fast also comes down fast.
When the glucose begins to suddenly crash your body wants to balance out the insulin and blood sugars by sending you a craving to eat more food. The food that is balances out this crash is what? You guessed it, SUGAR. One of the best ways to explain this to people is to use the analogy of using firewood to light a fire.
Think of carbs as kindling for the fire, they burn fast and quick and great for starting a fire but not for keeping it going. The opposite reaction can also have an effect and this is where can you eat too much protein or fat making you feel sluggish, tired, and lethargic.
A bit like eating too much roast meat on Christmas Day! In this case you would want to eat a small amount of carbohydrates to speed the fire up. This scenario is much less common but something to be aware of. This is what Metabolic Typing is all about.
Paying attention to the signals your body is sending and balance out the ratios of proteins, fats and carbohydrates accordingly. Grab a copy of our Nutrition report below that provides you with all the tools and information you need to get your food ratio right.
Click here to see more. One of the popular eating methods in recent times is the Ketogenic Diet. Since April I myself have been following the Keto diet as it perfectly aligned with my Metabolic Type of a protein type.
There was just a few things different that made all the difference and I feel amazing! Now before you rush out and adopt this eating because is worked so well for me, beware!
You must experiment and spend time learning what foods work best for you. When I eat the right meal for me I feel very satisfied with my meal and there is no energy spikes or slumps and there is definitely no cravings. A quick breakfast that I enjoy is a poached egg, bacon, cheese and avocado, no bread.
This type of breakfast enabled me to avoid the mid-morning sugar hit I struggled with for some time. This is typical of the person who eats a sugar loaded cereal or has a toast with jam for breakfast. The foods set you up to crash as there is too much sugar and not enough fat and protein.
Remember the firewood analogy? Another great food example is a great chicken recipe shown below. This is so delicious but also really quick to make and I often have this for lunch. For more information read our detailed article about the Keto diet and intermittent fasting.
What if you have your food under control is there anything else that can derail you? We briefly discussed this earlier when we discussed stress so it is important to also look at what triggers our cravings. Is it emotions? Is it eating the wrong foods at the previous meal?
Thank you for visiting nature. You are Pushing physical limits a browser annd with limited support for CSS. To obtain Emtabolism best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Obesity is associated with impaired inhibitory control over food intake.
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