Food Composition

Bomb calorimeter: measures heat energy released when foods are burned

Direct calorimetry: measures the amount of heat released

Indirect calorimetry: measures the amount of oxygen consumed

kcals per gram: carbohydrates 4, protein 4, fat 9, alcohol 7

Food Intake factors

Hunger: physiological drive for food

Appetite: a response to sight, smell, or taste of food that prompts or delays eating

Satiation: full feeling of satisfaction as a result of stretching receptors in the stomach

Satiety: feeling of satisfaction that occurs after eating which helps determine time between meals

Other factors that determine intake: stress eating and responding to external cues (like time of day or availability of appealing foods)

Hypothalmus: the control center (in the brain) that controls water balance, body temperature, and appetite

Energy Out: kcalories expended

Basal Metabolism: energy needed to maintain life when the body is at complete rest (determined after a 12 hour fast)

Basal Metabolic Rate (BMR): rate of energy metabolism under basal conditions

Resting energy expenditure (REE): similar to BMR but is less precise (by as much as 10%)

Physical Activity

Voluntary activities: deliberate muscular work: walking, lifting, climbing

Involuntary activities: heart beating, breathing, etc...

Thermal effect of food (TEF)

Estimates energy required to metabolize food

The sum of TEF and any increase in metabolic rate due to overeating is known as diet-induced thermogenesis (DIT)

Estimated at about 10% of total kcalories

Adaptive Thermogenesis

Adjustments in energy expenditure related to changes in environment (like cold) and to physiological events (like trauma and hormone shifts)