Energy expenditure, and therefore energy requirement, generally decreases with advancing age because of a decrease in basal metabolic rate BMR and physical activity.

The aim of the present study was to measure total energy expenditure EE and activity level in a group of healthy elderly sixteen men aged Age-related differences in body composition and their relationship to BMR and activity level were studied. EE was lower in elderly compared with young adults, partly due to a significantly lower BMR.

The lower BMR was not fully explained by the lower fat-free mass FFM in the elderly. This means that an older person has a lower BMR than a younger person of the same age. It is not always possible to determine BMR under strictly controlled conditions.

When the conditions are not completely controlled, the resultant measurement of energy expenditure is called the resting metabolic rate; for practical purposes, resting metabolic rate can be considered to be approximately equivalent to basal metabolic rate. PAR is the energy cost of an activity, expressed as a multiple of BMR.

PAR 1. watching TV, reading, writing, eating, playing cards. PAR 2. PAR 3. PAR 4. PAR 6. Some-one's overall physical activity level is calculated by summing the various activities during the day, multiplied by the time spent in each activity as a proportion of the day.

Again it is expressed as a multiple of BMR. The UK Department of Health classification of occupational work during the typical 8 hours working day excluding leisure activities are as follows:.

Moderately heavy work — PAR 2. These figures exclude leisure activities; a desirable physical activity level for cardiovascular and general health is 1.

Just keep in mind that these equations are guesstimates — not an exact measure of the number of calories that you burn. Some factors can be controlled but others cannot.

If, at any point in your life, you want to gain or lose weight or change your body composition, the first step is to understand factors that influence your resting metabolism. Even though there are many factors that affect RMR, most of them have a very small and temporary effect.

The two factors that have the greatest, and potentially long lasting, effect are starvation and loss of lean mass. To maintain healthy body composition it is important to avoid very low calorie dieting and maintain optimal levels of fat free mass.

It is especially important to maintain muscle mass as we age since some of the decline in RMR with age is due to loss of muscle. This is another reason why strength training is so important. Some people are hesitant to lift weights because they are afraid of getting big bulky muscles.

In fact, it is very difficult for most people to gain big bulky muscles and requires an individual to eat in a calorie surplus and follow a progressive overload strength training program that focuses on hypertrophy.

However, people do not need to be concerned that they will automatically bulk up from participating in strength training. The thermic effect of exercise is the energy required for physical activities.

We previously defined physical activity as bodily movement caused by muscle contraction. Energy is required for all muscle contractions, therefore, physical activity increases energy expenditure above basal or resting needs.

Certain factors can increase calorie burning during physical activity, for example, heavier people burn more calories while exercising because they are carrying more weight.

Increasing the intensity, frequency or duration of the activity will also increase calorie burning. As you become more efficient at an activity, calorie burning decreases. This means you need to increase the intensity, frequency, or duration if you want to burn the same number of calories.

You are not as efficient as these new sports and will burn calories faster which can help prevent weight gain as you adjust to a new routine. When it comes to total energy expenditure, the best way to manipulate your energy output to increase, decrease, or maintain weight is by changing your physical activity.

An easy way to estimate calorie burning through physical activity is to use activity factors. This table shows activity factors for various levels of activity. Once an activity factor is chosen, it can be used to estimate total energy expenditure by multiplying the activity factor by the estimated resting metabolic rate.

See Table 3. We will go over some examples of how this is put together in the total energy expenditure section. Table 3. The energy required for all the enzymatic reactions that take place during food digestion and the absorption and transportation of nutrients is called the thermic effect of food TEF and accounts for about 10 percent of total energy expended per day.

For example, if you eat kcals per day, approximately kcals will be required to digest, absorb, and transport the nutrients in that meal. TEF is the smallest component of energy expenditure so when estimating energy expenditure, emphasis is placed on resting metabolism and physical activity.

As the name implies, total energy expenditure TEE is how much energy your body burns over a 24 hour period. TEE includes both RMR and energy burned for physical activity.

When estimating TEE, we simply multiply RMR by an appropriate activity factor. Because there is a margin of error when estimating RMR and physical activity, we do not factor the thermic effect of food into the TEE calculation.

Calculate the total energy expenditure TEE for a lb man with a sedentary lifestyle. Calculate the total energy expenditure TEE for a lb woman who has an active lifestyle and exercises days a week for an hour.

Nutrition and Physical Fitness Copyright © by Angela Harter Alger is licensed under a Creative Commons Attribution 4. Energy in BMR includes energy that is used for normal body activities like cellular homeostasis, muscular activities, cardiac function, nerve function. Nearly 20 percent of the energy we take is used for brain functioning and metabolism.

The rest is all used in basal metabolism, that is, the energy that we require in a resting state, for the body to perform functions such as blood circulation, digestion, and breathing. There are various methods to measure BMR. One of them is through the evaluation of thyroid function.

It measures the oxygen consumption rate under basal conditions of overnight fast and rest from mental and physical activity. Since, the standard equipment for the measurement and calculation of BMR might not be readily available, the BMR can be easily estimated and measured from the oxygen consumed over a period of time by analysing the samples of expired air.

The test indirectly measures metabolic energy expenditure or the level of heat production. Low values in the results suggest that there is hypothyroidism. High values suggest that there exists presence of thyrotoxicosis.

These diseases are meant to increase BMR. Muscle mass: BMR is largely determined by the total body lean mass as lean mass requires a lot of energy to perform energetic activities.

And that instant energy is released through muscle activity. Anything that reduces lean mass will result in reduction of BMR. As the muscle mass increases, body consumes more amount of energy to maintain and control its basic everyday functions, this giving BMR a well-deserved boost in the metabolic activity.

Age: The basal metabolic rate decreases linearly with increase in age number. Basal metabolic rate is dependent on body size as it is indicated by weight, age, gender.

Age is a factor that has a major significance in human nutrition and diet. The child reaches the peak of basal heat production at two years of age. It keeps on gradually decreasing until the period of early adolescence years of age. After puberty, the BMR gradually keeps on decreasing. The changes in BMR is different for children and adults because adults are more susceptible to the changes in the environment, whereas children are always kept protected from the environmental changes.

Genetics and hormones: On the onset of adolescence, there is a difference in the basal heat production for males and females. Girls show the pre puberty rise two years earlier than boys and when boys reach puberty stage their basal energy expenditure is higher than girls and continues to be higher throughout the life.

This difference is because of the fact that men have greater muscularity and lean body mass lower percentage of adipose tissue than women. Genes do have a large influence on weight because of DNA and cell protein synthesis which controls the metabolism level.

Genetic factors are also responsible for heredity which affects the BMR. Pregnancy- BMR increases when a woman is pregnant. The total energy cost of pregnancy is largely due to an increased basal metabolic rate BMR. Supplements- Supplements do not necessarily mean chemicals and sedative drugs to lose or gain weight for increase or decrease in the BMR.

It involves intake of natural supplements such as. It is a universal rule that to lose weight, one needs to burn more calories than the actual consumption.

When the body is not fueled up with enough calories, it slows down the BMR to ensure it is storing whatever energy it can. Weather : Climate and body temperature are critical indicators of BMR as they determine the internal environment of an individual.

The BMR of people living in tropical climate is generally 5 to 20 percent higher than their counterparts living in more temperate areas. This is because it takes more energy to keep the body in a cooling state by releasing more heat.

Exercise performed in hot weather also imposes an extra, additional metabolic load on the body. The daily caloric need is the BMR value multiplied by a factor with a value between 1.

Calorie intake largely depends on factors such as age, size, height, sex, lifestyle, and overall health of a child. Intake of calories within limits does not lead to a healthy lifestyle and a healthy diet, as different foods tend to have different effects on the body of different sets of people.

For example, insulin level may rise after eating carbs as compared to eating fats or protein. Daily calorie need of a human differs from person to person. As people get older, their metabolic rate slows down thus their appetite and calorie intake also goes down.

It reduces the need for energy. From age 19 to 25 years, the recommended calorie intake for a women is 2, calories a day, but after 51 years, this falls to 1, Infection in Children - Part 3.

Disease and Conditions Congenital Hypothyroidism- Neonatal Screening Low Birth Weight Babies Feeding.