Interactive Summaries

Chapter 9: Energy Balance, Body Composition, and Weight Management

Energy In

There are three different sensations that influence our eating behavior. is the first process followed by which lets you know that you are full. The final process determines the interval between meals. The difference between hunger and appetite is that hunger is a(n) for food while appetite is the for food.
appears to makes a stronger contribution to satiety than fats or carbohydrates.
Exposure to tends to increase the amount we eat; exposure to tends to reduce it. NPY is a recently identified neuroendocrine factor that triggers decreased energy expenditure and increased food intake. It stimulates a desire to eat rather than a desire for energy. Fat cells produce , which tells the CNS how much fat the body is storing.

Energy Out

The minimum energy necessary to sustain life is called the . This type of energy is measured as either the basal metabolic rate or the . Over time, a person's RMR varies by less than 5%. A person's RMR as they age, because some lean tissue is replaced by fat. Lean tissue has metabolic activity than fat tissue.

Energy costs of physical activity depend on the activity's type, and intensity. The energy associated with fidgeting and maintenance of posture is called .

The energy output our bodies expend while digesting, absorbing, and metabolizing nutrients is collectively called the thermic effect of food. The TEF is lowest for and highest for . Typically, TEF accounts for approximately of total energy expenditure.

The measurement of energy expenditure is known as calorimetry. Determination of energy use by the body by measuring the heat released from an organism enclosed in a small insulated chamber is known as . Determination of energy use by the body by gas exchange or the measurement of oxygen uptake is . The method is emerging as the ‘gold standard’ of total energy expenditure methods.

Body Composition

is a key element in determining energy expenditure and is an important factor in disease risk. Weight and height measures can be used to calculate , which is correlated with body fatness and health risks. is the measure of body density. In , body density is calculated using the above water weight, the submerged weight and, the quantity of water displaced during submersion. DEXA, a technique used to measure bone density, can also be used to analyze by differentiating bone, other lean tissue, and fat. Done correctly, body composition estimates from skinfold thickness measurements correlate well with . This type of measurement is especially useful in tracking changes to subcutaneous fat distribution over time. Body fat distribution can be a risk factor for heart disease and diabetes. obesity is more common in and refers to excess fat being distributed around the hips and thighs. obesity is more common in and has fat distributed around the abdomen. Excess abdominal fat appears to raise which interferes with insulin function.

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