Energy Flashcards
How do we measure the gross energy of food
Bomb calorimetry
What is energy density
The energy per g of food
What % of total energy expenditure is from physical activity
25%
What percentage of TEE is from diet induced thermogenesis
10%
What percentage of TEE is from our basal metabolic rate
65%
What is BMR
The amount of energy expended while at rest inneutrally temperate environment in the post absorptive state or the amount of energy required for functioning of vital oragns
What 3 methods can we use to measure BMR
Prediction equations, calorimetry, doubly labelled water (DWL)
What is the gold standard method for measuring BMR
Doubly labelled water
What two prediction equations can be used to measure BMR
Harris-Benedict and Henry
What is indirect calorimetry
The amount of heat produced measured indirectly by measuring O2 consumed or CO2 produced
What conditions are required for accurate indirect calorimetry
12 hour fast
Physical and mental rest
Comfortable and warm environment
Lying down
What is diet induced thermogenesis
The energy recruited for eating/digestion/absorption/transport
What is the most variable component of energy expenditure
Physical activity
What are physical activity level (PAL) ratios
Multiple ratios based on activity intensity to estimate energy expenditure
What are the 3 general PAL ratios/factors recommended by SACN for women
Inactive- BMR x1.4
Moderate- BMR X 1.6
Very active- BMR x1.8
What are the 3 general PAL ratios/factors recommended by SACN for men
Inactive- BMR x1.4
Moderate- BMR X 1.7
Very active- BMR x1.9
What is the SACN dietary reference values for energy
Men- 2500kcal/day
Women- 2000kcal/day
What are the external regulators of energy intake
Palatability of food, variety, habit, psychological state, social events, resources
What are the internal regulators of energy intake
Gut fill cues (Ghrelin and leptin)
Blood glucose concentration
Signals from adipose tissue
What happens to BMR during under nutrition
Drops by up to 15%
How is kcal converted to Joules
1kcal=4.184 kJ
What is a calorie
The amount of heat energy required to raise 1g of water by 1 degree C at 15 degrees C
What is a joule
The work done when a point of application of 1 newton is displaced a distance of 1 meter in the direction of force
What are the 4 metabolic fuels
Carbohydrates, fat, protein and alcohol
