Unit 8 Calories Food Energy and Energy Balance

Unit 8 Calories! Food, Energy, and Energy Balance

Calories are a unit of measure n n Used to express the amount of energy produced by foods in the form of heat Calories are actually kilocalories or kcals = the amount of energy needed to raise the temperature of kilogram of water one degree Celsius. 1 kcal or calorie = 1 kilojoule

How do they determine the caloric value of foods? n n n Bomb calorimeter Burn the food entirely and measure the increase in temperature of the surrounding water Heat released by the food is approximately the same as the energy it supplies for the body

The body needs energy n n n Fuel muscular activity Growth Tissue repair and maintenance Chemically process nutrients Maintain body temperature Many other uses

Types of energy use n Basal Metabolism n n Physical activity n n Energy required to maintain normal body functions while at rest Energy needed for muscular work Dietary thermogenesis n Energy used to chemically process foods (process gives off heat)

Basal Metabolism n n Measure of the energy used when a body is in a state of complete rest Estimate your basal metabolic rate n n Men: body weight (lbs) times 11 Women: body weight (lbs) times 10 170 lb man X 11 = 1870 cals/day 135 lb woman X 10 = 1350 cals/day

Physical Activity n Amount spent depends on activity level n n Inactive Average Active 30% of basal metabolism calories 50% of basal metabolism calories 75% of basal metabolism calories Example: if basal metabolism = 1500 Inactive person 1500 X. 30 = 450 calories Average person 1500 X. 50 = 750 calories Active person 1500 X. 75 = 1125 calories

Activity level often overestimated n Don’t count time getting ready or breaks or timeouts

Dietary thermogenesis n n n Digesting food Absorbing food Utilizing nutrients Transporting nutrients to cells Energy escapes as heat Estimated at 10% of total calories

Adding it all up n Total daily need for calories = n n Basal metabolic rate 1500 Activity (inactive) 450 Dietary thermogenesis +195 TOTAL = 2145 calories

Where is the energy in foods? n n n Carbohydrates Proteins Fats 4 cal/gram 9 cal/gram

Which food has the most calories? n 1 Tablespoon margarine n 1 Tablespoon sugar n 1 Tablespoon steak

Which food has the most calories? n Half-cup peanuts n 205 calories n Medium-sized potato n 420 calories n One cup rice n 118 calories

Which food has the most calories? n Half-cup peanuts n 205 calories n Medium-sized potato n 420 calories n One cup rice n 118 calories

Most foods are a mixture n Quarter- pound hamburger n n 32 gm protein 39 gm carbohydrate 32 gm fat Total calories = 576

How is caloric intake regulated by the body? n n n Hunger: unpleasant physical and psychological sensations that lead people to acquire and ingest food Satiety: a feeling of fullness or of having had enough to eat Appetite: the desire to eat; a pleasant sensation that is aroused by thoughts of the taste and enjoyment of food

Energy Balance n Energy intake = energy need n Weight remains stable

Negative Energy Balance n Energy intake is less than energy need n Weight loss

Positive Energy Balance n Energy intake is more than energy need n Weight gain