Physiology, Health & Exercise
Lesson 12
Exercise & Metabolism
Exercise & metabolism
Include:
 Need for energy
 Dietary recommendations for health
 Energy balance
2
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
3
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 labellingkilocalories are also called Calories C)
 1kcal = 4.18kJ
4
Which nutrients store energy?
Copy and complete this table
Remember 1kcal = 4.18kJ
Nutrient
Energy content
kJ/g
Carbohydrate
16
Protein
17
Kcal/g
Fat
9
Alcohol
7
5
How is energy released?
 Potential energy in food released during
respiration to synthesise ATP (cell’s energy
currency)
6
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)
7
Guideline Daily Allowances
 Food labels often have GDA (Guideline
Daily Allowances)
 A bench mark to show you the
recommended daily levels
Calories
Fat
Salt
Women
(GDA)
2000
70g
5g
Men
(GDA)
2500
95g
7g
8
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
Year
Carbohydrate
%
1943
52
Fat %
34
Protein
%
14
1995
47
38
15
2007
50
30
20
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
9
Estimated average
requirements (EAR)
 Also guidelines from Department of Health
on EAR
 Depend on age & gender
10
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
11
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?
12
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
13
If eat more kJ/day than
required
 Positive energy balance
 Extra energy stored  weight gain
14
Energy input
Energy use
“normal” weight
Overeating/
drinking
Low exercise
overweight
underweight
Excessive
exercise
Stress
High BMR
Illness
Diet
Eating disorder
15
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.
16
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
17
18
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
19
Consequences of Obesity
 Elevates blood lipid levels (LDL)
 Can greatly increase risk of type II
diabetes (NIDD- non-insulin dependent
diabetes)
20
Homework
 Monitor your energy intake over a 24
hour period
 Bring your data to the lesson on
08/02/2010
21