Physiology, Health & Exercise

Lesson 12Exercise & Metabolism

2

Exercise & metabolism

Include: Need for energy Dietary recommendations for health Energy balance

3

Why does our body need energy?

Write down at least 3 reasons Growth & repair of body tissues Produce heat to keep us warm Keep e.g. heart contracting Drive metabolic reactions Pregnancy & lactation

4

How do we get energy?

From the food we eat! Energy measured in kJ/g or kcal/g SI unit is kJ/g Traditionally energy measured in calories,

1000 cal = 1kcal Most often used on food labelling-

kilocalories are also called Calories C) 1kcal = 4.18kJ

5

Which nutrients store energy?Copy and complete this tableRemember 1kcal = 4.18kJ

Nutrient Energy content

kJ/g Kcal/g

Carbohydrate 16

Protein 17

Fat 9

Alcohol 7

6

How is energy released?

Potential energy in food released during respiration to synthesise ATP (cell’s energy currency)

7

Dietary recommendations for health

Getting it right UK Department of Health publishes

dietary guidelines Guideline Daily Allowances (GDA) Recommended % of daily energy from

carbohydrate, fat & protein Estimated average requirements (EAR)

8

Guideline Daily Allowances

Food labels often have GDA (Guideline Daily Allowances)

A bench mark to show you the recommended daily levels

Women (GDA)

Men (GDA)

Calories 2000 2500

Fat 70g 95g

Salt 5g 7g

9

Guideline Daily Allowances Also guidelines on recommended % of daily

energy (excluding alcohol- which is a carbohydrate but not a nutrient!) that should come from carbohydrates protein and fat

What changes have occurred in these values?Why do you think therehave been changessince 1995?High fat diet will provide more energy than a low fat diet

Year Carbohydrate %

Fat % Protein %

1943 52 34 14

1995 47 38 15

2007 50 30 20

10

Estimated average requirements (EAR)

Also guidelines from Department of Health on EAR

Depend on age & gender

11

Estimated average requirements (EAR) 1MJ = 1000kJ Data assumes a fairly inactive life style. Why?

Age (years)

EAR males MJ/day

EAR females MJ/day

11-14 9.27 7.72

15-18 11.51 8.83

19-50 10.6 8.1

12

Energy balance

Getting it wrong What are the consequences if we get it

wrong? e.g. Consume too much energy or too

little energy or % supplied by various components

differs greatly from the guidelines?

13

If eat fewer kJ/day than required

Negative energy balance Body energy stores used to meet the

demand Regular shortfall in energy intake

weight loss

14

If eat more kJ/day than required

Positive energy balance Extra energy stored weight gain

15

Energy useEnergy input

“normal” weight

Overeating/drinking

Low exercise

IllnessDietEating disorder

Excessive exerciseStressHigh BMR

overweight

underweight

16

Energy balance Must consider level of activity as

well as diet. e.g. high level of activity will require

a diet with loads of kJ However more likely to have a poor

diet, high in fat, combined with a sedentary lifestyle which causes the problems.

17

Energy balance Is evidence in UK that fat

consumption has actually declined since 1990- but greater inactivity means that obesity and other conditions are on the increase

18

19

Consequences of Obesity Increases risk of CHD & stroke, even

without other risk factors being present

More excess fat you carry, especially around your middle, greater risk to your heart

Obesity raises blood pressure & blood cholesterol levels

20

Consequences of Obesity Elevates blood lipid levels (LDL) Can greatly increase risk of type II

diabetes (NIDD- non-insulin dependent diabetes)

21

Homework Monitor your energy intake over a

24 hour period Bring your data to the lesson on

08/02/2010