© British Nutrition Foundation 2010

Energy – a balancing act

Sarah SchenkerNutrition Scientist

Georgine LeungNutrition Scientist

16th June 2010

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Overview

• What is energy?

• Energy balance: In vs. Out

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What is energy?

1kJ = 1000J1MJ = 1000kJ1kcal = 4.18kJ

• The power to do work, or produce heat or light.

• Measured in kilojoules (kJ) or megajoules (MJ).

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Energy from food

Carbohydrate(16kJ/g)

Protein(17kJ/g)

Fat(37kJ/g)

Macronutrients:

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Alcohol?

1 gram of alcohol provides 29kJ.

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Nutrient contribution to energy

29

37

16 17

0

5

10

15

20

25

30

35

40

Carbohydrate Protein Alcohol Fat

kJ p

er g

ram

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Energy intakes

• Estimated Average Requirements (EARs)

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Question

If we include alcohol in our diet, provision of energy from which macronutrient should decrease?

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Energy needs vary

• Basal metabolic rate (BMR)

- Age

- Sex

- Body size/composition

• Level of physical activity

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Basal metabolic rate (BMR)

• Rate of energy use to maintain basic functions of the body.

• Accounts for 75% of an individual’s energy needs.

• Men usually have a higher BMR than women.

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Physical activity levels (PAL)

• Intensity and duration.

• Children and young people: at least 60 mins (every day).

• With activities for bone strength, muscle strength and flexibility.

• Adults: at least 30 mins (5 times per week).

Energy expenditure = BMR x PAL

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Why do men have higher BMRs?

a. Men tend to have more muscle.

b. Men tend to be bigger.

c. Both of the above.

d. Men tend to be more active.

e. All of the above.

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Key stages in life

ChildrenAdolescents

AdultsOlder adults

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Energy balance

Energy inFood and drinks

Energy outActivity

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How much activity?

Walking the dogRunning

Swimming Watching

TV

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Positive energy balance

Energy inFood and drinks

Energy outActivity

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Being overweight and obese increases risk of:

• certain cancers;

• heart disease;

• Stroke;

• Type 2 Diabetes.

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Negative energy balance

Energy inFood and drinks

Energy outActivity

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Being underweight increases risk of:

• hair loss;

• dry, patchy skin;

• weakened immune system;

• osteoporosis;

• infertility;

• heart failure.

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• It is very important to achieve a healthy weight

• Body Mass Index (BMI) =

Monitoring energy balance

weight (kg) . height (m) x height (m)

Recommended BMI range (kg/m2)Underweight less than 18.5Normal 18.5 - less than 25Overweight 25 - less than 30Obese 30 - 40Very obese over 40

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How balanced are we?

How many people in the UK are overweight or obese?

(Please express your answers in percentage.)

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BNF is grateful for financial support from the Agricultural and Horticultural Development Board

to enable us to develop these eSeminars.

For further information, go to: www.nutrition.org.uk

www.foodafactoflife.org.uk