In the United States, more than 70 percent of adults are overweight or have obesity. Having this extra weight raises your risk for many health conditions, such as type 2 diabetes , heart disease , kidney disease , and certain cancers.

Reaching and staying at a healthy weight can be challenging. But a having a healthy lifestyle, including healthy eating patterns and regular physical activity, can help you lose weight. It can also lower your chance of developing weight-related health conditions. You gain weight when you take in more calories through food and drinks than you use up from physical activity and daily living.

But there are many different factors that can affect weight gain, such as:. Getting to and staying at a healthy weight involves finding a balance of food and activity. To lose weight, you need to take in fewer calories than you use up.

Some ways to do this are:. You may decide to do these lifestyle changes on your own, or you may decide to try a weight-loss diet or program. Before you start, it's important to check with your health care provider first.

Your provider can tell you what a healthy weight is for you, help you set goals, and give you tips on how to lose weight. If making lifestyle changes or doing a weight-loss program are not enough to help you lose weight, your provider may prescribe medicines.

The prescription medicines to treat overweight and obesity work in different ways. Some may help you feel less hungry or full sooner. Others may make it harder for your body to absorb fat from the foods you eat. Another treatment is weight loss surgery. Your provider may recommend the surgery if you have severe obesity or serious obesity-related health problems and you have not been able to lose enough weight.

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Why is weight control important? What factors affect weight and health? But there are many different factors that can affect weight gain, such as: The world around you.

Your home, community, and workplace all may affect how you make daily lifestyle choices. For example: It is often easier to find food and beverages high in calories, sugar, and fat. Consume more than the body burns, weight goes up.

Less, weight goes down. But what about the type of calories: Does it matter whether they come from specific nutrients-fat, protein, or carbohydrate? Specific foods-whole grains or potato chips? And what about when or where people consume their calories: Does eating breakfast make it easier to control weight?

Does eating at fast-food restaurants make it harder? The good news is that many of the foods that help prevent disease also seem to help with weight control-foods like whole grains, vegetables, fruits, and nuts.

And many of the foods that increase disease risk-chief among them, refined grains and sugary drinks-are also factors in weight gain. Conventional wisdom says that since a calorie is a calorie, regardless of its source, the best advice for weight control is simply to eat less and exercise more.

Yet emerging research suggests that some foods and eating patterns may make it easier to keep calories in check, while others may make people more likely to overeat. This article briefly reviews the research on dietary intake and weight control, highlighting diet strategies that also help prevent chronic disease.

When people eat controlled diets in laboratory studies, the percentage of calories from fat, protein, and carbohydrate do not seem to matter for weight loss.

In studies where people can freely choose what they eat, there may be some benefits to a higher protein, lower carbohydrate approach. For chronic disease prevention, though, the quality and food sources of these nutrients matters more than their relative quantity in the diet.

And the latest research suggests that the same diet quality message applies for weight control. Low-fat diets have long been touted as the key to a healthy weight and to good health. In fact, study volunteers who follow moderate- or high-fat diets lose just as much weight, and in some studies a bit more, as those who follow low-fat diets.

Part of the problem with low-fat diets is that they are often high in carbohydrate, especially from rapidly digested sources, such as white bread and white rice. And diets high in such foods increase the risk of weight gain, diabetes, and heart disease.

See Carbohydrates and Weight , below. Higher protein diets seem to have some advantages for weight loss, though more so in short-term trials; in longer term studies, high-protein diets seem to perform equally well as other types of diets. But there are a few reasons why eating a higher percentage of calories from protein may help with weight control:.

Higher protein, lower carbohydrate diets improve blood lipid profiles and other metabolic markers, so they may help prevent heart disease and diabetes. Replacing red and processed meat with nuts, beans, fish, or poultry seems to lower the risk of heart disease and diabetes.

Researchers tracked the diet and lifestyle habits of , men and women for up to 20 years, looking at how small changes contributed to weight gain over time. People who ate more nuts over the course of the study gained less weight-about a half pound less every four years. Lower carbohydrate, higher protein diets may have some weight loss advantages in the short term.

Read more about carbohydrates on The Nutrition Source. Milled, refined grains and the foods made with them-white rice, white bread, white pasta, processed breakfast cereals, and the like-are rich in rapidly digested carbohydrate.

So are potatoes and sugary drinks. The scientific term for this is that they have a high glycemic index and glycemic load. Such foods cause fast and furious increases in blood sugar and insulin that, in the short term, can cause hunger to spike and can lead to overeating-and over the long term, increase the risk of weight gain, diabetes, and heart disease.

For example, in the diet and lifestyle change study, people who increased their consumption of French fries, potatoes and potato chips, sugary drinks, and refined grains gained more weight over time-an extra 3. The good news is that many of the foods that are beneficial for weight control also help prevent heart disease, diabetes, and other chronic diseases.

Conversely, foods and drinks that contribute to weight gain—chief among them, refined grains and sugary drinks—also contribute to chronic disease. Read more about whole grains on The Nutrition Source.

Whole grains-whole wheat, brown rice, barley, and the like, especially in their less-processed forms-are digested more slowly than refined grains.

So they have a gentler effect on blood sugar and insulin, which may help keep hunger at bay. The same is true for most vegetables and fruits. Read more about vegetables and fruits on The Nutrition Source. The weight control evidence is stronger for whole grains than it is for fruits and vegetables.

Fruits and vegetables are also high in water, which may help people feel fuller on fewer calories. Read more about nuts on The Nutrition Source. Nuts pack a lot of calories into a small package and are high in fat, so they were once considered taboo for dieters.

As it turns out, studies find that eating nuts does not lead to weight gain and may instead help with weight control, perhaps because nuts are rich in protein and fiber, both of which may help people feel fuller and less hungry.

Read more about calcium and milk on The Nutrition Source. The U. dairy industry has aggressively promoted the weight-loss benefits of milk and other dairy products, based largely on findings from short-term studies it has funded. One exception is the recent dietary and lifestyle change study from the Harvard School of Public Health, which found that people who increased their yogurt intake gained less weight; increases in milk and cheese intake, however, did not appear to promote weight loss or gain.

Read more about healthy drinks on The Nutrition Source. Like refined grains and potatoes, sugary beverages are high in rapidly-digested carbohydrate. See Carbohydrates and Weight , above. These findings on sugary drinks are alarming, given that children and adults are drinking ever-larger quantities of them: In the U.

The good news is that studies in children and adults have also shown that cutting back on sugary drinks can lead to weight loss. Read more on The Nutrition Source about the amount of sugar in soda, fruit juice, sports drinks, and energy drinks, and download the How Sweet Is It?

guide to healthier beverages. Ounce for ounce, fruit juices-even those that are percent fruit juice, with no added sugar- are as high in sugar and calories as sugary sodas.

Read more about alcohol on The Nutrition Source. While the recent diet and lifestyle change study found that people who increased their alcohol intake gained more weight over time, the findings varied by type of alcohol. They eat meals that fall into an overall eating pattern, and researchers have begun exploring whether particular diet or meal patterns help with weight control or contribute to weight gain.

Portion sizes have also increased dramatically over the past three decades, as has consumption of fast food-U. children, for example, consume a greater percentage of calories from fast food than they do from school food 48 -and these trends are also thought to be contributors to the obesity epidemic.

Following a Mediterranean-style diet, well-documented to protect against chronic disease, 53 appears to be promising for weight control, too.

The traditional Mediterranean-style diet is higher in fat about 40 percent of calories than the typical American diet 34 percent of calories 54 , but most of the fat comes from olive oil and other plant sources.

The diet is also rich in fruits, vegetables, nuts, beans, and fish. A systematic review found that in most but not all studies, people who followed a Mediterranean-style diet had lower rates of obesity or more weight loss.

There is some evidence that skipping breakfast increases the risk of weight gain and obesity, though the evidence is stronger in children, especially teens, than it is in adults.

But there have been conflicting findings on the relationship between meal frequency, snacking, and weight control, and more research is needed.

Since the s, portion sizes have increased both for food eaten at home and for food eaten away from home, in adults and children. One study, for example, gave moviegoers containers of stale popcorn in either large or medium-sized buckets; people reported that they did not like the taste of the popcorn-and even so, those who received large containers ate about 30 percent more popcorn than those who received medium-sized containers.

People who had higher fast-food-intake levels at the start of the study weighed an average of about 13 pounds more than people who had the lowest fast-food-intake levels. They also had larger waist circumferences and greater increases in triglycercides, and double the odds of developing metabolic syndrome.

Weight gain in adulthood is often gradual, about a pound a year 9 -too slow of a gain for most people to notice, but one that can add up, over time, to a weighty personal and public health problem.

Though the contribution of any one diet change to weight control may be small, together, the changes could add up to a considerable effect, over time and across the whole society. Willett WC, Leibel RL. Dietary fat is not a major determinant of body fat. Am J Med. Melanson EL, Astrup A, Donahoo WT.

The relationship between dietary fat and fatty acid intake and body weight, diabetes, and the metabolic syndrome. Ann Nutr Metab. But is fasting healthy, and does intermittent fasting work? Fasting—abstaining from eating for some period of time—is an ancient practice that is safe when not taken to extremes.

Traditionally, the benefits of fasting have been both spiritual and physical. People who fast for religious reasons often report a stronger focus on spiritual matters during the fast. Physically, a simple fast lowers blood sugar, reduces inflammation, improves metabolism, clears out toxins from damaged cells and has been linked to lower risk of cancer, reduced pain from arthritis and enhanced brain function.

A common intermittent fasting schedule might restrict eating to the hours of a. to p. But there is no specific, prescribed schedule. Some people have more or less generous eating windows, setting the rule that they will not eat after, say, p.

During a period without eating, insulin levels drop to the point that the body begins burning fat for fuel. Numerous studies have demonstrated the benefits of intermittent fasting for weight loss. One possible reason for the success of intermittent fasting is that most practitioners have quit the habit of eating during the late evening and night hours.

There are certain people who should not try intermittent fasting without first checking with their doctor, such those with diabetes or heart disease. It sounds counterintuitive, but many people find success losing weight—especially initially—by eating more fat, not less.

The theory is that by eating so many healthy fats and restricting carbohydrates, you enter an altered metabolic state in which you force your body to begin relying on fat for energy, burning away your fat stores instead of sugar for fuel.

Research does show that keto is an effective way to jump-start weight loss and improve blood-sugar levels. However, it is hard to maintain, and to date we are lacking long-term studies that show it to be a sustainable eating pattern for keeping weight off.

Because both weight loss and overall health are tied to some basic eating patterns, we have developed the Harvard Healthy Eating Plate as a model for meal planning and for your overall balanced diet. Imagine a round dinner plate with a line running vertically down its center dividing it evenly in two.

One half of the plate should be taken up by equal portions of whole grains not refined grains like white bread and white rice and healthy protein such as fish, nuts, beans and poultry—not red meat or processed meats. Two-thirds of the other half should be filled with vegetables, with the remaining portion consisting of fruit.

To the other side of the plate, imagine a vessel containing healthy oils such as canola or olive oil. Use it for cooking or at the table instead of butter. Adhering to its guidelines will optimize your chances of remaining healthy and of maintaining a desirable body weight. Thanks for visiting.

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Environmental restructuring empha-sizes frequenting dining facilities that produce appealing foods of lower energy density and providing ample time for eating a wholesome meal rather than grabbing a candy bar or bag of chips and a soda from a vending machine.

Busy lifestyles and hectic work schedules create eating habits that may contribute to a less than desirable eating environment, but simple changes can help to counter-act these habits.

Commanders of military bases should examine their facilities to identify and eliminate conditions that encourage one or more of the eating habits that promote overweight.

Some nonmilitary employers have increased healthy eating options at worksite dining facilities and vending machines. Although multiple publications suggest that worksite weight-loss programs are not very effective in reducing body weight Cohen et al.

Opting for high-fat snack foods from strategically placed vending machines or snack shops combined with allowing insufficient time to prepare affordable, healthier alternatives. Major obstacles to exercise, even in highly motivated people, include the time it takes to complete the task and the inaccessibility of facilities or safe places to exercise.

Environmental interventions emphasize the many ways that physical activity can be fit into a busy lifestyle and seek to make use of whatever opportunities are available HHS, The availability of safe sidewalks and parks and alternative methods of transportation to work, such as walking or bicycling, also enhance the physical activity environment.

Management of overweight and obesity requires the active participation of the individual. Nutrition professionals can provide individuals with a base of information that allows them to make knowledgeable food choices.

Nutrition education is distinct from nutrition counseling, although the contents overlap considerably. Nutrition counseling and dietary management tend to focus more directly on the motivational, emotional, and psychological issues associated with the current task of weight loss and weight management.

It addresses the how of behavioral changes in the dietary arena. Nutrition education on the other hand, provides basic information about the scientific foundation of nutrition that enables people to make informed decisions about food, cooking methods, eating out, and estimating portion sizes.

Nutrition education programs also may provide information on the role of nutrition in health promotion and disease prevention, sports nutrition, and nutrition for pregnant and lactating women.

Effective nutrition education imparts nutrition knowledge and its use in healthy living. For example, it explains the concept of energy balance in weight management in an accessible, practical way that has meaning to the individual's lifestyle, including that in the military setting.

Written materials prepared by various government agencies or by nonprofit health organizations can be used effectively to provide nutrition education. However, written materials are most effective when used to reinforce informal classroom or counseling sessions and to provide specific information, such as a table of the calorie content of foods.

The format of education programs varies considerably, and can include formal classes, informal group meetings, or teleconferencing. A common background among group members is helpful but seldom possible. Educational formats that provide practical and relevant nutrition information for program participants are the most successful.

For example, some military weight-management programs include field trips to post exchanges, restaurants fast-food and others , movies, and other places where food is purchased or consumed Vorachek, The involvement of spouses and other family members in an education program increases the likelihood that other members of the household will make permanent changes, which in turn enhances the likelihood that the program participants will continue to lose weight or maintain weight loss Hart et al.

Particular attention must be directed to involvement of those in the household who are most likely to shop for and prepare food. Unless the program participant lives alone, nutrition management is rarely effective without the involvement of family members.

Weight-management programs may be divided into two phases: weight loss and weight maintenance. While exercise may be the most important element of a weight-maintenance program, it is clear that dietary restriction is the critical component of a weight-loss program that influences the rate of weight loss.

Activity accounts for only about 15 to 30 percent of daily energy expenditure, but food intake accounts for percent of energy intake. Thus, the energy balance equation may be affected most significantly by reducing energy intake. The number of diets that have been proposed is almost innumerable, but whatever the name, all diets consist of reductions of some proportions of protein, carbohydrate CHO and fat.

The following sections examine a number of arrangements of the proportions of these three energy-containing macronutrients. A nutritionally balanced, hypocaloric diet has been the recommendation of most dietitians who are counseling patients who wish to lose weight.

This type of diet is composed of the types of foods a patient usually eats, but in lower quantities. There are a number of reasons such diets are appealing, but the main reason is that the recommendation is simple—individuals need only to follow the U.

Department of Agriculture's Food Guide Pyramid. The Pyramid recommends that individuals eat a variety of foods, with the majority being grain products e. In using the Pyramid, however, it is important to emphasize the portion sizes used to establish the recommended number of servings.

For example, a majority of consumers do not realize that a portion of bread is a single slice or that a portion of meat is only 3 oz. A diet based on the Pyramid is easily adapted from the foods served in group settings, including military bases, since all that is required is to eat smaller portions.

Even with smaller portions, it is not difficult to obtain adequate quantities of the other essential nutrients.

Many of the studies published in the medical literature are based on a balanced hypocaloric diet with a reduction of energy intake by to 1, kcal from the patient's usual caloric intake. The U. Meal replacement programs are commercially available to consumers for a reasonably low cost.

The meal replacement industry suggests replacing one or two of the three daily meals with their products, while the third meal should be sensibly balanced. In addition, two snacks consisting of fruits, vegetables, or diet snack bars are recommended each day.

A number of studies have evaluated long-term weight maintenance using meal replacement, either self-managed Flechtner-Mors et al. The largest amount of weight loss occurred early in the studies about the first 3 months of the plan Ditschuneit et al. One study found that women lost more weight between the third and sixth months of the plan, but men lost most of their weight by the third month Heber et al.

All of the studies resulted in maintenance of significant weight loss after 2 to 5 years of follow-up. Hill's review of Rothacker pointed out that the group receiving meal replacements maintained a small, yet significant, weight loss over the 5-year program, whereas the control group gained a significant amount of weight.

Active intervention, which included dietary counseling and behavior modification, was more effective in weight maintenance when meal replacements were part of the diet Ashley et al. Meal replacements were also found to improve food patterns, including nutrient distribution, intake of micronutrients, and maintenance of fruit and vegetable intake.

Long-term maintenance of weight loss with meal replacements improves biomarkers of disease risk, including improvements in levels of blood glucose Ditschuneit and Fletchner-Mors, , insulin, and triacylglycerol; improved systolic blood pressure Ditschuneit and Fletchner-Mors, ; Ditschuneit et al.

Winick and coworkers evaluated employees in high-stress jobs e. The meal replacements were found to be effective in reducing weight and maintaining weight loss at a 1-year follow-up.

In contrast, Bendixen and coworkers reported from Denmark that meal replacements were associated with negative outcomes on weight loss and weight maintenance. However, this was not an intervention study; participants were followed for 6 years by phone interview and data were self-reported.

Unbalanced, hypocaloric diets restrict one or more of the calorie-containing macronutrients protein, fat, and CHO. The rationale given for these diets by their advocates is that the restriction of one particular macronutrient facilitates weight loss, while restriction of the others does not.

Many of these diets are published in books aimed at the lay public and are often not written by health professionals and often are not based on sound scientific nutrition principles. For some of the dietary regimens of this type, there are few or no research publications and virtually none have been studied long term.

Therefore, few conclusions can be drawn about the safety, and even about the efficacy, of such diets. The major types of unbalanced, hypocaloric diets are discussed below. There has been considerable debate on the optimal ratio of macronutrient intake for adults. This research usually compares the amount of fat and CHO; however, there has been increasing interest in the role of protein in the diet Hu et al.

Although the high-protein diet does not produce significantly different weight loss compared with the high-CHO diet Layman et al. High-protein, low-CHO diets were introduced to the American public during the s and s by Stillman and Baker and by Atkins Atkins, ; Atkins and Linde, , and more recently, by Sears and Lawren While most of these diets have been promoted by nonscientists who have done little or no serious scientific research, some of the regimens have been subjected to rigorous studies Skov et al.

There remains, however, a lack of randomized clinical trials of 2 or more years' duration, which are needed to evaluate the potent beneficial effect of weight loss accomplished using virtually any dietary regimen, no matter how unbalanced on blood lipids. In addition, longer studies are needed to separate the beneficial effects of weight loss from the long-term effects of consuming an unbalanced diet.

These claims are unsupported by scientific data. Although these diets are prescribed to be eaten ad libitum, total daily energy intake tends to be reduced as a result of the monotony of the food choices, other prescripts of the diet, and an increased satiety effect of protein. In addition, the restriction of CHO intake leads to the loss of glycogen and marked diuresis Coulston and Rock, ; Miller and Lindeman, ; Pi-Sunyer, Thus, the relatively rapid initial weight loss that occurs on these diets predominantly reflects the loss of body water rather than stored fat.

This can be a significant concern for military personnel, where even mild dehydration can have detrimental effects on physical and cognitive performance.

For example, small changes in hydration status can affect a military pilot's ability to sense changes in equilibrium. Results of several recent studies suggest that high-protein, low-CHO diets may have their benefits. In addition to sparing fat-free mass Piatti et al. Furthermore, a percent protein diet reduced resting energy expenditure to a significantly lesser extent than did a percent protein diet Baba et al.

The length of these studies that examined high-protein diets only lasted 1 year or less; the long-term safety of these diets is not known. Low-fat diets have been one of the most commonly used treatments for obesity for many years Astrup, ; Astrup et al.

The most extreme forms of these diets, such as those proposed by Ornish and Pritikin , recommend fat intakes of no more than 10 percent of total caloric intake.

Although these stringent diets can lead to weight loss, the limited array of food choices make them difficult to maintain for extended periods of time by individuals who wish to follow a normal lifestyle.

More modest reductions in fat intake, which make a dietary regimen easier to follow and more acceptable to many individuals, can also promote weight loss Astrup, ; Astrup et al.

For example, Sheppard and colleagues reported that after 1 year, obese women who reduced their fat intake from approximately 39 percent to 22 percent of total caloric intake lost 3. Results of recent studies suggest that fat restriction is also valuable for weight maintenance in those who have lost weight Flatt ; Miller and Lindeman, Dietary fat reduction can be achieved by counting and limiting the number of grams or calories consumed as fat, by limiting the intake of certain foods for example, fattier cuts of meat , and by substituting reduced-fat or nonfat versions of foods for their higher fat counterparts e.

Over the past decade, pursuit of this latter strategy has been simplified by the burgeoning availability of low-fat or fat-free products, which have been marketed in response to evidence that decreasing fat intake can aid in weight control.

The mechanisms for weight loss on a low-fat diet are not clear. Weight loss may be solely the result of a reduction in total energy intake, but another possibility is that a low-fat diet may alter metabolism Astrup, ; Astrup et al.

Support for the latter possibility has come from studies showing that the short-term adherence to a diet containing 20 or 30 percent of calories from fat increased hour energy expenditure in formerly obese women, relative to an isocaloric diet with 40 percent of calories from fat Astrup et al.

Over the past two decades, fat consumption as a percent of total caloric intake has declined in the United States Anand and Basiotis, , while average body weight and the proportion of the American population suffering from obesity have increased significantly Mokdad et al.

Several factors may contribute to this seeming contradiction. First, all individuals appear to selectively underestimate their intake of dietary fat and to decrease normal fat intake when asked to record it Goris et al.

If these results reflect the general tendencies of individuals completing dietary surveys, then the amount of fat being consumed by obese and, possibly, nonobese people, is greater than routinely reported. Second, although the proportion of total calories consumed as fat has decreased over the past 20 years, grams of fat intake per day have remained steady or increased Anand and Basiotis, , indicating that total energy intake increased at a faster rate than did fat intake.

Coupled with these findings is the fact that since the early s, the availability of low-fat and nonfat, but calorie-rich snack foods e. However, total energy intake still matters, and overconsumption of these low-fat snacks could as easily lead to weight gain as intake of their high-fat counterparts Allred, Two recent, comprehensive reviews have reported on the overall impact of low-fat diets.

Astrup and coworkers examined four meta-analyses of weight change that occurred on intervention trials with ad libitum low-fat diets. They found that low-fat diets consistently demonstrated significant weight loss, both in normal-weight and overweight individuals. A dose-response relationship was also observed in that a 10 percent reduction in dietary fat was predicted to produce a 4- to 5-kg weight loss in an individual with a BMI of Most low-fat diets are also high in dietary fiber, and some investigators attribute the beneficial effects of low-fat diets to the high content of vegetables and fruits that contain large amounts of dietary fiber.

The rationale for using high-fiber diets is that they may reduce energy intake and may alter metabolism Raben et al. The beneficial effects of dietary fiber might be accomplished by the following mechanisms: 1 caloric dilution most high-fiber foods are low in calories and low in fat ; 2 longer chewing and swallowing time reduces total intake; 3 improved gastric and intestinal motility and emptying and less absorption French and Read, ; Leeds, ; McIntyre et al.

Dietary fiber is not a panacea, and the vast majority of controlled studies of the effects of dietary fiber on weight loss show minimal or no reduction in body weight LSRO, ; Pasman et al. Many individuals and companies promote the use of dietary fiber supplements for weight loss and reductions in cardiovascular and cancer risks.

Numerous studies, usually short-term and using purified or partially purified dietary fiber, have shown reductions in serum lipids, glucose, or insulin Jenkins et al. Long-term studies have usually not confirmed these findings LSRO, ; Pasman et al. Current recommendations suggest that instead of eating dietary fiber supplements, a diet of foods high in whole fruits and vegetables may have favorable effects on cardiovascular and cancer risk factors Bruce et al.

Such diets are often lower in fat and higher in CHOs. Very-low-calorie diets VLCDs were used extensively for weight loss in the s and s, but have fallen into disfavor in recent years Atkinson, ; Bray, a; Fisler and Drenick, The VLCDs used most frequently consist of powdered formulas or limited-calorie servings of foods that contain a high-quality protein source, CHO, a small percentage of calories as fat, and the daily recommendations of vitamins and minerals Kanders and Blackburn, ; Wadden, The servings are eaten three to five times per day.

The primary goal of VLCDs is to produce relatively rapid weight loss without substantial loss in lean body mass. To achieve this goal, VLCDs usually provide 1. VLCDs are not appropriate for all overweight individuals, and they are usually limited to patients with a BMI of greater than 25 some guidelines suggest a BMI of 27 or even 30 who have medical complications associated with being overweight and have already tried more conservative treatment programs.

Additionally, because of the potential detrimental side effects of these diets e. On a short-term basis, VLCDs are relatively effective, with weight losses of approximately 15 to 30 kg over 12 to 20 weeks being reported in a number of studies Anderson et al.

However, the long-term effectiveness of these diets is somewhat limited. Approximately 40 to 50 percent of patients drop out of the program before achieving their weight-loss goals. In addition, relatively few people who lose large amounts of weight using VLCDs are able to sustain the weight loss when they resume normal eating.

In two studies, only 30 percent of patients who reached their goal were able to maintain their weight loss for at least 18 months. Within 1 year, the majority of patients regained approximately two-thirds of the lost weight Apfelbaum et al.

In a more recent study with longer followup, the average regain over the first 3 years of follow-up was 73 percent. However, weight tended to stabilize over the fourth year.

At 5 years, the dieters had maintained an average of 23 percent of their initial weight loss. At 7 years, 25 percent of the dieters were maintaining a weight loss of 10 percent of their initial body weight Anderson et al.

It appears that VLCDs are more effective for long-term weight loss than hypocaloric-balanced diets. In a meta-analysis of 29 studies, Anderson and colleagues examined the long-term weight-loss maintenance of individuals put on a VLCD diet with behavioral modification as compared with individuals put on a hypocaloric-balanced diet.

They found that VLCD participants lost significantly more weight initially and maintained significantly more weight loss than participants on the hypocaloric-balanced diet see Table Almost any kind of assistance provided to participants in a weight-management program can be characterized as support services.

These can include emotional support, dietary support, and support services for physical activity. The support services used most often are structured in a standard way. Other services are developed to meet the specific needs of a site, program, or the individual involved.

With few exceptions, almost any weight-management program is likely to be more successful if it is accompanied by support services Heshka et al. However, not all services will be productively applicable to all patients, and not all can be made available in all settings. Furthermore, some weight-loss program participants will be reluctant to use any support services.

Psychological and emotional factors play a significant role in weight management. Counseling services are those that consider psychological issues associated with inappropriate eating and that are structured to inform the patient about the nature of these issues, their implications, and the possibilities available for their ongoing management.

This intervention is less elaborate, intense, and sustaining than psychotherapy services. For example, it should be useful to help patients understand the existence and nature of a sabotaging household or the phenomenon of stress-related eating without undertaking continuing psychotherapy.

A counselor or therapist can provide this service either in individual or group sessions. These counselors should, however, be sufficiently familiar with the issues that arise with weight-management programs, such as binge eating and purging. Short-term, individual case management can be helpful, as can group sessions because patients can hear the perspective of other individuals with similar weight-management concerns while addressing their individual concerns Hughes et al.

Psychotherapy services, both individual and group, can also be useful. However, the costs of this type of service limits its applicability to many patients.

Nevertheless, the value for individual patients can be substantial, and the option should not be dismissed simply because of cost. Concerns about childhood abuse, emotional linkages to sustaining obesity fat-dependent personality , and the management of coexisting mental health problems are the kinds of issues that might be addressed with this type of support service.

The individual therapist can structure the format of the therapy but, as with counseling services, the therapist should be familiar with weight-management issues.

Nonprofessional patient-led groups and counseling, such as those available with organized programs like Take Off Pounds Sensibly and Overeaters Anonymous, can be useful adjuncts to weight-loss efforts.

These programs have the advantages of low cost, continuing support and encouragement, and a semi-structured approach to the issues that arise among weight-management patients.

Their disadvantage is that, since the counseling is nonprofessional in nature, the programs are only as good as the people who are involved. These peer-support programs are more likely to be productive when they are used as a supplement to a program with professional therapists and counselors.

In Overeaters Anonymous, a variant of these groups is a sponsor-system program that pairs individuals who can help one another. Certain commercial programs like Weight Watchers and Jenny Craig can also be helpful.

Since commercial groups have their own agenda, caution must be exercised to avoid contradictions between the advice of professional counselors and that of the supportive commercial program.

Since the counselors in commercial programs are not likely to be professionals, the quality of counseling offered by these programs varies with the training of the counselors. Many communities offer supplemental weight-management services.

Educational services, particularly in nutrition, may be provided through community adult education using teaching materials from nonprofit organizations such as the American Heart Association, the American Diabetes Association, and government agencies FDA, National Institutes of Health, and U.

Department of Agriculture. Many community hospitals have staff dietitians who are available for out-patient individual counseling Pavlou et al. However, the military's TRICARE health services contracts would need to be modified to include dietitian services from community hospitals or other community services since these contracts do not currently include medical nutrition therapy and therefore dietitian counseling.

The family unit can be a source of significant assistance to an individual in a weight-management program. For example, program dropout rates tend to be lower when a participant's spouse is involved in the program Jeffery et al.

With simple guidance and direction, the involvement of the spouse as a form of reinforcement rather than as a source of discipline and monitoring can become a resource to assist in supporting the participant. However, individual family members or the family as a group can become an obstacle when they express reluctance to make changes in food and eating patterns within the household.

Issues of family conflict become more complex when the participants are children or adolescents or when spouses are reluctant to relinquish status quo positions of control. A variety of Internet- and web-related services are available to individuals who are trying to manage their weight Davison, ; Gray and Raab, ; Riva et al.

As with any other Internet service, the quality of these sites varies substantially Miles et al. An important role for weight-management professionals is to review such sites so they can recommend those that are the most useful. The use of e-mail counseling services by military personnel who travel frequently or who are stationed in remote locations has been tested at one facility; initial results are promising James et al.

The use of web-based modalities by qualified counselors or facilitators located at large military installations would extend the accessibility of such services to personnel located at small bases or stationed in remote locations.

Support is also required for military personnel who need to enhance their levels of physical fitness and physical activity. All branches of the services have remedial physical fitness training programs for personnel who fail their fitness test, but support is also needed for those who need to lose weight and for all personnel to aid in maintaining proper weight.

Support services should include personnel, facilities, and equipment, and should provide practical advice on how to begin and progress through physical training routines including proper use of training equipment and how to prevent musculoskeletal injuries , as well as advice on when and how to eat in conjunction with physical activity demands.

Success in the promotion of weight loss can sometimes be achieved with the use of drugs. Almost all prescription drugs in current use cause weight loss by suppressing appetite or enhancing satiety. One drug, however, promotes weight loss by inhibiting fat digestion.

To sustain weight loss, these drugs must be taken on a continuing basis; when their use is discontinued, some or all of the lost weight is typically regained. Therefore, when drugs are effective, it is expected that their use will continue indefinitely. For maximum benefit and safety, the use of weight-loss drugs should occur only in the context of a comprehensive weight-loss program.

In general, these drugs can induce a 5- to percent mean drop in body weight within 6 months of treatment initiation, but the effect can be larger or smaller depending on the individual.

As with any drug, the occurrence of side effects may exclude their use in certain occupational contexts. Recognition that weight-related diseases, such as diabetes and hypertension, occur in individuals with BMI levels below 25, and that weight loss improves these conditions in these individuals, suggests that indications for weight-loss drugs need to be individualized to the specific patient.

A number of hormonal and metabolic differences distinguish obese people from lean people Leibel et al. Weight loss alters metabolism in obese individuals, limiting energy expenditure and reducing protein synthesis. This alteration suggests that the body may attempt to maintain an elevated body weight.

The facts that genetics might play a role in hormonal and metabolic differences between people and that weight loss alters metabolism imply that obesity is not a simple psychological problem or a failure of self-discipline. Instead, it is a chronic metabolic disease similar to other chronic diseases and it involves alterations of the body's biochemistry.

Like most other chronic diseases that require ongoing pharmacotherapy to prevent the recurrence of symptoms, obesity management and relapse prevention may someday be accomplished through this form of treatment.

The following sections provide a brief review of the mechanisms of action, efficacy, and safety of prescription agents that have been approved for weight loss and the various over-the-counter substances that are promoted for weight loss.

Energy intake may be curbed by reducing hunger or appetite or by enhancing satiety. Summary of Potential Mechanisms of Action of Obesity Drugs. Some obesity drugs may reduce the preference for dietary fat or refined CHOs Blundell et al. For example, the drug orlistat reduces the absorption of fat, which results in energy loss in the feces; other drugs not approved for obesity treatment reduce CHO absorption Heal et al.

These drugs may produce sufficiently adverse effects, such as oily stools or increased flatus, so that patients reduce consumption of high-fat foods in favor of less energy-dense foods McNeely and Benfield, ; Sjostrom et al.

Obesity drugs also may increase activity levels or stimulate metabolic rate. Drugs such as fenfluramine or sibutramine were reported to increase energy expenditure in some studies Arch, ; Astrup et al. Fluoxetine, although not approved for obesity treatment, has been shown to increase resting metabolic rate Bross and Hoffer, Ephedrine and caffeine, which act on adenosine receptors, may increase metabolic rate, reduce body-fat storage, and increase lean mass Liu et al.

With one exception orlistat , all currently available prescription obesity drugs act on either the adrenergic or serotonergic systems in the central nervous system to regulate energy intake or expenditure Bray, b. Table summarizes the mechanism of action of pharmacological agents used for treating obesity, which are discussed in detail below.

Prescription Pharmacological Agents for Weight-Loss Treatment and Mechanisms of Action. Phentermine, an adrenergic agent, is the most commonly used prescription drug for obesity and has one of the lowest costs of all prescription agents.

Weight loss is comparable with that of other single agents Silverstone, Diethylpropion, phendimetrazine, and benzphetamine are other adrenergic agents that stimulate central norepinephrine secretion and produce weight loss similar to that of phentermine Griffiths et al.

The categorization of phendimetrazine and benzphetamine as Drug Enforcement Agency Schedule III drugs may have limited their use, although little evidence exists to suggest that they have a higher abuse potential than does phentermine. Diethylpropion was reported to have a higher reinforcement potential in nonhuman primates than that of the other Schedule III and IV adrenergic drugs Griffiths et al.

No currently available agents for treating obesity are exclusively serotonergic. Fluoxetine and sertraline are selective serotonin reuptake inhibitors that produce weight loss Bross and Hoffer, ; Goldstein et al.

Fluoxetine produced good weight loss after 6 months, but 1-year results were not different from those of placebo treatment Goldstein et al. Sertraline also produced short-term weight loss Ricca et al.

Sibutramine inhibits reuptake of both norepinephrine and serotonin in central nervous system neurons. Blood pressure rose slightly in normotensive subjects, but fell in hypertensive subjects Heal et al.

Decreases in fasting blood glucose, insulin, waist circumference, waist-hip ratio, and computerized tomography-estimated abdominal fat were greater with sibutramine than with placebo Heal et al.

The greater weight losses observed in the sibutramine group compared with the placebo group may be responsible for the greater improvements in other parameters. Common complaints with the use of centrally active adrenergic and serotonergic obesity drugs include dry mouth, fatigue, hair loss, constipation, sweating, sleep disturbances, and sexual dysfunction Atkinson et al.

Sibutramine can increase blood pressure and pulse rate in occasional patients and may cause dizziness and increased food intake Cole et al.

Mazindol may cause penile discharge van Puijenbroek and Meyboom, Orlistat binds to lipase in the gastrointestinal tract and inhibits absorption of about one-third of dietary fat Hollander et al.

Average weight loss on orlistat is about 8 to 11 percent of initial body weight at 1 year James WP et al. Although weight loss may be responsible for some of the observed improvements, orlistat lowered LDL independently of its effect on weight loss.

Acarbose is an alpha glucosidase inhibitor that inhibits or delays absorption of complex CHOs Wolever et al. This drug is approved by FDA for the treatment of diabetes mellitus, but not for weight loss.

Although it produces modest weight loss in animals, it has minimal or no effect on humans. Adverse side effects of orlistat include abdominal cramping, increased flatus formation, diarrhea, oily spotting, and fecal incontinence Hollander et al. These adverse effects may serve as a behavior modification tool to reduce the level of fat in the diet and presumably to reduce energy intake.

Orlistat has been shown to produce small reductions in serum levels of fat-soluble vitamins. The manufacturer recommends that a vitamin supplement containing vitamins A, D, E, and K be prescribed for patients taking orlistat.

A variety of drugs currently on the market for other conditions, but not approved by FDA for obesity treatment, have been evaluated for their ability to induce weight loss.

Metformin Lee and Morley, , cimetidine Rasmussen et al. Additional studies are needed to support these findings. Although chronic diseases often require treatment with more than one drug, few studies have evaluated combination therapy for obesity. Private practitioners have used various combinations in an off-label fashion.

The available data suggest that combination therapy is somewhat more effective than therapy with single agents. Combinations such as phentermine and fenfluramine or ephedrine and caffeine produce weight losses of about 15 percent or more of initial body weight compared with about 10 percent or less with single drug use.

However, due to reported side-effects of cardiac valve lesions and pulmonary hypertension, fenfluramine and dexfenfluramine are no longer available. Results of tests using combinations of phentermine with selective serotonin reuptake inhibitors mainly fluoxetine or sertraline have been reported in abstracts or preliminary reports Dhurandhar and Atkinson, ; Griffen and Anchors, These combinations produced weight losses somewhat less than that of the combination treatment of ephedrine-caffeine, but greater than that of treatment with single agents Dhurandhar and Atkinson, Anchors used the combination of phentermine and fluoxetine in a large series of patients and suggested that this combination is safe and effective.

Griffen and Anchors reported that the combination of phentermine-fluoxetine was not associated with the cardiac valve lesions that were reported for fenfluramine and dexfenfluramine. In , Congress passed the Dietary Supplement Health and Education Act, which exempted dietary supplements including those promoted for weight loss from the requirement to demonstrate safety and efficacy.

People can use a paper diary, mobile app, or dedicated website to record every item of food that they consume each day. They can also measure their progress by recording their weight on a weekly basis. Those who can track their success in small increments and identify physical changes are much more likely to stick to a weight loss regimen.

People can also keep track of their body mass index BMI using a BMI calculator. Regular exercise is vital for both physical and mental health. Increasing the frequency of physical activity in a disciplined and purposeful way is often crucial for successful weight loss.

One hour of moderate-intensity activity per day, such as brisk walking, is ideal. If one hour per day is not possible, the Mayo Clinic suggests that a person should aim for a minimum of minutes every week. People who are not usually physically active should slowly increase the amount of exercise that they do and gradually increase its intensity.

This approach is the most sustainable way to ensure that regular exercise becomes a part of their lifestyle. In the same way that recording meals can psychologically help with weight loss, people may also benefit from keeping track of their physical activity.

If the thought of a full workout seems intimidating to someone who is new to exercise, they can begin by doing the following activities to increase their exercise levels:. Individuals who have a low risk of coronary heart disease are unlikely to require medical assessment ahead of starting an exercise regimen.

However, prior medical evaluation may be advisable for some people, including those with diabetes. Anyone who is unsure about safe levels of exercise should speak to a healthcare professional. It is possible to consume hundreds of calories a day by drinking sugar-sweetened soda, tea, juice, or alcohol.

Unless a person is consuming a smoothie to replace a meal, they should aim to stick to water or unsweetened tea and coffee. Adding a splash of fresh lemon or orange to water can provide flavor. Avoid mistaking dehydration for hunger. An individual can often satisfy feelings of hunger between scheduled meal times with a drink of water.

Therefore, people should avoid estimating a serving size or eating food directly from the packet. It is better to use measuring cups and serving size guides. Guessing leads to overestimating and the likelihood of eating a larger-than-necessary portion. These sizes are not exact, but they can help a person moderate their food intake when the correct tools are not available.

Many people benefit from mindful eating, which involves being fully aware of why, how, when, where, and what they eat. People who practice mindful eating also try to eat more slowly and savor their food, concentrating on the taste.

Making a meal last for 20 minutes allows the body to register all of the signals for satiety. Many social and environmental cues might encourage unnecessary eating. For example, some people are more likely to overeat while watching television.

Others have trouble passing a bowl of candy to someone else without taking a piece. By being aware of what may trigger the desire to snack on empty calories, people can think of ways to adjust their routine to limit these triggers.

Stocking a kitchen with diet-friendly foods and creating structured meal plans will result in more significant weight loss. People looking to lose weight or keep it off should clear their kitchen of processed or junk foods and ensure that they have the ingredients on hand to make simple, healthful meals.

Doing this can prevent quick, unplanned, and careless eating. Planning food choices before getting to social events or restaurants might also make the process easier. Some people may wish to invite friends or family members to join them, while others might prefer to use social media to share their progress.

Weight loss is a gradual process, and a person may feel discouraged if the pounds do not drop off at quite the rate that they had anticipated. Some days will be harder than others when sticking to a weight loss or maintenance program.

A successful weight-loss program requires the individual to persevere and not give up when self-change seems too difficult. Some people might need to reset their goals, potentially by adjusting the total number of calories they are aiming to eat or changing their exercise patterns.

The important thing is to keep a positive outlook and be persistent in working toward overcoming the barriers to successful weight loss. Successful weight loss does not require people to follow a specific diet plan, such as Slimming World or Atkins. Instead, they should focus on eating fewer calories and moving more to achieve a negative energy balance.

Weight loss is primarily dependent on reducing the total intake of calories, not adjusting the proportions of carbohydrate , fat, and protein in the diet.

A reasonable weight loss goal to start seeing health benefits is a 5—10 percent reduction in body weight over a 6-month time frame. Most people can achieve this goal by reducing their total calorie intake to somewhere in the range of 1,—1, calories per day.

A diet of fewer than 1, calories per day will not provide sufficient daily nutrition. After 6 months of dieting, the rate of weight loss usually declines, and body weight tends to plateau because people use less energy at a lower body weight.

Following a weight maintenance program of healthful eating habits and regular physical activity is the best way to avoid regaining lost weight.

People who have a BMI equal to or higher than 30 with no obesity-related health problems may benefit from taking prescription weight-loss medications. These might also be suitable for people with a BMI equal to or higher than 27 with obesity-related diseases.

However, a person should only use medications to support the above lifestyle modifications. Achieving and maintaining weight loss is possible when people adopt lifestyle changes in the long term.

Regardless of any specific methods that help a person lose weight, individuals who are conscious of how and what they eat and engage in daily physical activity or regular exercise will be successful both in losing and keeping off excess weight. I have an injury that is keeping me from physical exercise.

Is there any way to continue keeping the weight off? If your injury allows, you can do some simple exercises while sitting in a chair, such as lifting light weights.