Exercise energy expenditure

Energy expenditure comes in the form of basal metabolism, maintenance of body temperature, and physical exercise. 

Thermic effect of food It has long been observed that eating a meal increases energy expenditure, a phenomenon also known as diet-induced thermogenesis or specific dynamic action. The increase depends on the type and quantity of food consumed. As an example, the effect of a carbohydrate-rich meal on the oxygen consumption of volunteers before and after exercise is shown in Figure 2.5. 

Three factors improve the health of individuals with type II diabetes regular exercise, use of thiazolidinediones, and dietary restriction. We have seen that exercise activates AMPK, as does adiponectin, and that thiazolidinediones increase the concentration of adiponectin in plasma, increasing insulin sensitivity. Dietary restriction may act by regulating the expression of genes that encode proteins involved in fatty acid oxidation and in energy expenditure via thermogenesis. 

There are two main components of daily energy expenditure basal or resting energy expenditure and energy expended in exercise. 

Fuels for the body are limited to carbohydrates, fats, and proteins. In the American diet, these fuels are consumed in a ratio of approximately 46 42 12 with the recommended ratio being closer to 53 35 12 (.5). Thus in a nongrowing adult, these ratios provide estimates of the fuel use for daily activities. The primary fuels for exercise are carbohydrates and fats. Chapter 3 examines utilization of specific fuels during aerobic exercise. As the amount of daily exercise increases, there is an increased energy expenditure and hence increased need for energy nutrients usually reflected in increased food consumption, decreased body fat, or both (see Chapter 9). 

The methods of indirect and direct calorimetry may not always result in the same values for energy expenditure. Indirect calorimetry is a measure of the heat produced by oxidative processes. Direct calorimetry measures the rate of dissipation of heat from the body. An increase in the rate of heat production, as with exercise, may not always result in an immediate, measurable increase in heat released by the body (from the skin). Instead, the increase in heat production may result in a rise in body temperature. That part of the energy requirement used to raise... 

Doubly Labeled Water Technique for Determining Energy Expenditure 303 EXERCISE... 

The amount of triglyceride in the adipose tissue the body (i.e. how fat a person is) represents the cumulative sum, over time, of the difference between energy intake (as food) and energy expenditure (as exercise and resting metabolism). Excess triglyceride leads to hypertrophy of the fat cells in the adipose tissue which has been said to be the defining pathology of obesity. 

Many people find that their mobility becomes less as their age advances. Not only do they become less robust, locomotor problems, often secondary to arthritic conditions, supervene. These further restrict the opportunities for exercise. If calorie intake is not reduced to compensate for reduced energy expenditure, weight gain is likely to ensue, sometimes to the point of frank obesity. To prevent this happening, as well as to reverse any unwanted weight gain, dietary counselling should be offered. 

Interestingly, there is an inverse relationship between the degree of physical activity and the prevalence of type 2 diabetes. For every 500-kcal increase in daily energy expenditure, there is a 6% decrease in the age-adjusted risk of type 2 diabetes. This effect is independent of both body weight and a parental history of diabetes. The mechanism of the protective effect of exercise is thought to be an increased sensitivity to insufin in skeletal muscle and adipose tissue. 

Richard D. Exercise and the neurobiological control of food intake and energy expenditure. Int J Obesity Related Metab Disord 1995 19(Suppl 4) S73-S79. 

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