Energy Balance

Question 1

What is Energy Balance?

Answer 1

Energy Intake - Total Energy Expenditure

Question 2

What are the components of energy expenditure and their percentage composition?

Answer 2

15-45% Physical Activity
10% Thermic Effect of Feeding
50-75% Basal Metabolic Rate

Question 3

What determines BMR?

Answer 3

Body mass

Question 4

What are the 3 main ways of measuring expenditure?

Answer 4

Direct Calorimetry
Indirect Calorimetry
Non-Calorimetric Methods

Question 5

What is Direct Calorimetry?

Answer 5

Measuring heat loss from the participant in a closed system/room

Question 6

What is indirect calorimetry?

Answer 6

O2 Consumption/CO2 Production measured

Question 7

What are the issues of direct calorimetry?

Answer 7

Cant monitor rapid changes
Issues using exercise equipment
Can’t determine fuel use
Space limitations

Question 8

What are the issues associated with indirect calorimetry?

Answer 8

• Measurements may affect behaviour

- Difficult to use for prolonged periods

Question 9

What is the gold standard for indirect calorimetry?

Answer 9

Doubly Labelled Water

Question 10

How does Doubly Labelled water work?

Answer 10

Uses stable heavy isotopes (Deuterium/2H and ^18O)
^18O is lost more quickly because it is in both CO2 and H2O, so the difference in the rates of elimination is used to estimate CO2 production

Question 11

What are the issues associated with Doubly labelled water?

Answer 11

• Expensive
• Specialist equipment required
• Expertise required
• Only useful over extended periods
• No info about substrate

Question 12

How do self-report and recall measures work to calculate energy expenditure?

Answer 12

-Activity diaries throughout the day using activity scores/MET value for every activity that could be done

Question 13

What are the problems of self report measures of energy expenditure?

Answer 13

• Not sensitive
• Issues with recall
• Extremely time consuming and tedious for both participant and experimenter

Question 14

What are the pros and cons of pedometers/accelerometers?

Answer 14

Pros Cheap, accessible and good at predicting ambulatory activities
Cons: Misses non-ambulatory activities like weightlifting, cycling, etc

Question 15

What are the problems of HR monitors for measuring energy expenditure?

Answer 15

• Highly variable between individuals
• Can be affected by other factors like stress
• Less good at lower intensity

Question 16

What is a potential solution to the cons of things like pedometers, HR monitors, accelerometers, etc?

Answer 16

Multi-sensor devices that measure all of them to eliminate some of the error of any individual measure

Question 17

How do you work out the gross energy of foods?

Answer 17

Combustion in a calorimeter

Question 18

Why is the gross energy of a food not necessarily the energy we get from it?

Answer 18

-Not all food is digestible/can be oxidised (e.g fibre/nitrogen, respectively)

Question 19

What are the general energy values associated with the macronutrients?

Answer 19

• Fats: 9kcal/g
• Carbs: 4kcal/g
• Protein: 4kcal/g
• Alcohol 7kcal/g

Question 20

What are the 3 predominant measures of assessing energy intake?

Answer 20

• Food diaries
• Food recall questionnaires
• Weighed food and fluid intake