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Unformatted text preview: Lecture 19 - Energy Balance and Regulation of Feeding Behavior Calorie values- CArbs (4.1)- Fats (9.3)- Proteins (4.1)- Ethanol (very high! 7.1 of the carbs) Components of total body energy expenditure – in a person, not cell *The total body energy expenditure > intake loss weight *Total < intake deposit as TG gain weight- Total energy expenditure = heat produced + work on environment o Physical activity (variable) o Adaptive thermogenesis (variable, regulated by brain; response to temp. and found in brown adipose tissue) o Obligatory energy expenditure (required for normal cellular and organ functions)- How many calories do you need to maintain balance? o Females about 2000-2200 o Males a little more 2400-2800 Thermogenesis- The generation of heat when an organism is at rest and not performing work on the environment- Results from reactions in energy metabolism that are exothermic in the forward reaction (Na + /K + ATPase, Ca 2+ ATPase, actinomysin ATPase) Basal metabolic rate- Term we use to refer to how much energy the body is expending under sets of conditions o Of calorie consumption in a resting, awake in the post absorptive sate (fasting) o Measurements are made in the absence of muscular activity at a comfortable environmental temperature o Roughly corresponds to the obligate energy expenditure required for the performance of cellular and organ functions- This isn’t a set constant and varies! o For most individual about 1kal/kg/hour (80 watts)- Basal metabolic rate is subject to regulation o Decrease about 10% during sleep o Decrease about 40% during starvation o Decrease with age (approx 10% between age 20- 60) o Slightly higher in males than females o Key regulator = thyroid hormone a critical regulator) Low thyroid hormone low metabolic rate High = high metabolic rate- Energy expenditure also determined by the physical activity that one carries out!- Physical Activity Levels (PALs) The biggest variable in the energy expenditure equations o Brisk walking (1 hr) 4-5 x BMR o Cycling/dancing (45 min) 6-7 x BMR o Soccer, cross country skiing, running (8 min miles) 10-12 x BMR Adaptive Thermogenesis- Heat production in response to environmental temperature of diet- Generates heat to help protect the organism against cold exposure- Modifies energy expenditure to help regulate energy balance in response to change in diet o This will help your body adjust to the varying diet- Responses to cold o Increased heat production Shivering – acute/transient muscle energy expenditure with no work performed Adaptive thermogenesis – short and long term • Two to four fold increase in O2 consumption in rodents • 5-10% increase in humans in the short term, more pronounced in the long term due to increased thyroid hormone production Decreased heat loss – vasoconstriction Behavioral changes can do both (exercise, more clothes) - Diet-inducted changes in energy expenditure o...
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