Energy balance + requirements

Question 1

How is energy produced?

Answer 1

Comes in the form of ATP via oxidative phosphorylation

Question 2

How do you calculate energy balance/change in energy

Answer 2

Question 3

Why do we need to maintain energy balance?

Answer 3

It prevents

• unintentional weight loss = increased morbidity + mortality
• overfeeding can cause serious derangements in biochemistry

Question 4

What does positive energy balance lead to?

Answer 4

Obesity development

Growth

Pregnancy

Recovery from depletion

Question 5

What does negative energy balance lead to?

Answer 5

Wasting disease

Anorexia

Voluntary weight loss

Starvation

Question 6

What are the 3 major sources of energy expenditure in the body?

Answer 6

1. Basic metabolic rate (BMR) = energy needed for cells just to function
2. Thermic effect of food = 10% of energy expenditure
3. Physical activity

• Daily variation in energy needs are due to changes in physical activity*
• People tend to consume a constant weight or volume of food*
• Amount of food eaten not ependent upon energy density of food*
• Foods with greater energy density are more palatable + appealing*

Question 7

An individual’s energy expenditure varies by…

Answer 7

• body size
• age
• sex
• climate
• genetics
• body composition
• hormones
• disease processes
• psychological state

Question 8

How do we estimate energy intake?

Answer 8

Using schofield equation

The basal metabolic rate is calculated based on age, sex, body weight in kg

also, Henry equation

Question 9

BMR will only provide enough energy to maintain basic functions.

What other things do we need energy for?

Answer 9

Food digestion

Activity

Maintaining temperature

Growth + repair

Question 10

What composes of the total energy expenditure?

Answer 10

Question 11

How do you calculate physical activity level?

Answer 11

PAL = total energy expenditure / BMR

An individual’s PAL depends upon how active they are

Question 12

What is injury factor?

How does it affect BMR?

Answer 12

Injury/fever increases BMR

Level of energy required depends on degree of injury

Total energy requirement doesn’t increase if BMR increases due to injury

Question 13

What does a small increase in positive energy balance over time lead to?

Answer 13

Obesity

Question 14

How to assess nutritional status?

Answer 14

ABCD

anthropometry - height, weight, subcutaneous fat

biochemical + haematological parameters

clinical + physical assessment

dietary intake