AQA Core Biology 1a (ii) - Human Biology.
Diet and Exercise.
A Balanced Diet Does a Lot to Keep You Healthy.
1) For good health, your diet must provide the energy you need (but no more).
2) But that is not all, because the different food groups have different uses in the body, you need to have the right balance of foods as well.
So you need:
...enough carbohydrates and fats to keep warm and provide energy.
...enough protein for growth, cell repair and cell replacement.
...enough fibre to keep everything moving smoothly through your digestive system.
...and tiny amount of various vitamins and minerals skin, bones, blood and everything else generally healthy.
3) People who's diet is badly out of balance are said to be malnourished (not the same as starvation). Malnourished people can be fat or thin, or unhealthy in other ways. For example, a lack in vitamin C can cause scurvy, a deficiency disease which causes problems with the skin, joints and gums. Different deficiency diseases are caused by a lack of other nutrients.
People's Energy Needs Vary Because of Who They Are...
1) You need energy to fuel the chemical reactions in your body that keep you alive. These reactions are called your metabolism, and the speed at which they occur is your metabolic rate.
2) There are slight variations in the resting metabolic rate of different people. For example, muscle needs more energy than fatty tissue, which means (all other things being equal) people with a higher proportion of muscle to fat in their bodies have a higher metabolic rate.
3) However, physically bigger people are likely to have a higher metabolic rate than smaller people. The bigger you are the more energy your body needs to be supplied with (because you have more cells).
4) Men tend to have a slightly higher rate than women, they're slightly bigger and have a larger proportion of muscle. Other genetic factors may also have some effect.
5) And regular exercise can boost your resting metabolic rate because it builds muscle.
...and Because of What They Do.
1) When you exercise, you obviously need more energy, so your metabolic rate goes up during exercise and stays high for quite some time after you finish (particularly if the exercise is strenuous).
2) So people who have more active jobs need more energy on a daily basis, builders require more energy per day then office workers, for instance. The table shows the average kilojoules burned per minute when doing different activities:
Watching TV 7
Cycling (5mph) 21
Jogging (5mph) …