chapter 10- energy balance

energy balance

the relationship between energy intake and energy expenditure

bomb calorimeter

calorie values can be derived by directly measuring calorie content using this device

the body uses energy for 3 main purposes

basal metabolism, physical activity, and the digestion, absorption, and processing of ingested nutrients

basal metabolism

BMR, represents the minimum amount of energy expended in a fasting state to keep a resting, awake body alive in a warm, quiet environment, 60-70% of daily total energy expenditure

BMR and RMR calorie estimate

.9 kcal/kg per hour for women and 1.0 kcal/kg per hour for men

physical activity

increases energy expenditure above and beyond basal energy needs by as much as 25-40%

thermic effect of food

the energy the body uses to digest, absorb, transport, store, and metabolize the nutrients we consume in our diet, 5-10% of energy consumed each day

thermogenesis

the process of heat production by humans and other organisms, makes a fairly small contribution to overall energy expenditure

direct calorimetry

estimates energy expenditure by measuring the amount of heat released by the body

hunger

the physiological drive to find and eat food, is controlled by internal body mechanisms

appetite

the psychological drive to eat, is affected mostly by external factors that encourage us to eat

feelings of satiety

elected first by the sensory aspects of food and the knowledge that a meal has been eaten, also chewing is linked to releasing histamine which affects the satiety center in the brain

signals to eat

concentrations of macronutrients in the blood begin to fall and the body starts using energy from body stores, stimulating appetite

BMI doesn’t apply to

children, teens, older adults, and pregnant/lactating women

underwater weighing

determines body volume by measuring body wet when under water and body weight in air and entering these values into a mathematical formula

air displacement

determines body volume by measuring the space a person takes up inside a small chamber like a BodPod

skinfold thickness

estimates total body fat content, calipers measure the fat layer directly under the skin at multiple sites and then enter those values into a mathematical formula

bioelectrical impedance

estimates body fat content by sending a painless, low-energy electrical current through the body, adipose tissue resists electrical flow more than lean tissue b/c adipose tissue contains less electrolytes and water

abdominal adipose cells

release fat directly to the liver via the portal view which interferes with the liver’s ability to clear insulin and alters the liver’s lipoprotein metabolism, also it increases inflammation, insulin resistance, blood clotting, and blood vessel constriction