Physiology, Health & Exercise Lesson 12 zExercise & 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! zEnergy measured in kJ/g or kcal/g zSI unit is kJ/g zTraditionally energy measured in calories, 1000 cal = 1kcal zMost often used on food labelling- kilocalories are also called Calories C) z1kcal = 4.18kJ

5 Which nutrients store energy? Copy and complete this table Remember 1kcal = 4.18kJ NutrientEnergy content kJ/gKcal/g Carbohydrate16 Protein17 Fat9 Alcohol7

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 yGuideline Daily Allowances (GDA) yRecommended % of daily energy from carbohydrate, fat & protein yEstimated 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 Fat70g95g Salt5g7g

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 there have been changes since 1995? High fat diet will provide more energy than a low fat diet YearCarbohydrate % Fat %Protein %

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

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 Illness Diet Eating disorder Excessive exercise Stress High 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 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