Energy balance (copy)

Energy balance is…

The relationship between energy input (energy consumed) & energy output (energy used)

Energy is needed to…

Keep all organs functioning properly

Keep us warm

Allow our muscles to work

Provide energy stores

Make chemical reactions happen

Energy is measured in…

Kilocalories (kcal) or kilojoules (kJ)

How do our bodies obtain energy?

From the food we eat

Basal metabolic rate (BMR) is…

The amount of energy needed to carry out bodily functions

How does BMR vary between different groups of people?

Toddlers & children have a higher BMR because they are growing rapidly

Men tend to have a higher BMR than women

Elderly have a lower BMR because they have less muscle mass

Physical activity level (PAL) is…

The energy used for all types of movement

Body mass index (BMI) is…

A measurement which compares weight to height

This is helpful in identifying if you are underweight, have an ideal weight or obese

How is BMI calculated?

BMI = weight (kg) ÷ height (m)²

How much energy is gained from 1g carbohydrate?

3.75kcal

16kJ

How much energy is gained from 1g protein?

4 kcal

17kJ

How much energy is gained from 1g fat?

9kcal

37kJ

How can the amount of energy obtained from different foods be calculated?

Grams of nutrient × the kcals / kJ

What is recommended % of energy that we should obtain from carbohydrates?

50%

What is recommended % of energy that we should obtain from protein?

15%

What is recommended % of energy that we should obtain from fats?

35% (or less)

Calories are…

A unit of energy that is used to give the energy yield of foods & the energy expenditure on the body

Factors that influence energy requirements

Gender

Age

Activity levels

Health

Pregnancy & lactation

Size, body weight & genetics

How does gender influence energy requirements?

Males tend to need more energy than females because they are usually bigger & have a greater muscle mass

How does age influence energy requirements?

Babies & young children need more energy because they are rapidly growing & developing

Teenagers also need more energy because their bodies are changing & they are still growing

As people get older, their energy requirements decrease because they are no longer growing & are often less active

How do activity levels influence energy requirements?

People who do a lot of exercise or have an active job need more energy to replenish what was used up through their activity

People wit lower activity levels have lower energy requirements

How does health influence energy requirements?

Diseases & infection can increase energy requirements as more energy is needed to fight off the illness

However, it may also reduce appetite, causing weight loss as energy is used up from energy reserves instead

How does pregnancy & lactation influence energy requirements?

Pregnant women need more energy as they have a higher BMI to grow & maintain the foetus & placenta

Lactating women also need more energy to supply nutrients in their breast milk

How does size, body weight & genetics influence energy requirements?

People who have a lean body need more energy because they are metabolically more active

This means that they are more likely to burn off excess energy than those who have a heavier body type