Diet and Health
From ZuluNotes - Free Leaving Cert Notes
Contents |
Energy
Energy can be defined as the ability to do work. Our bodies need it to do everyday activities, walk, talk etc.
The Role of Energy in the body
We consume plant foods which provide us with energy to
- perform our everyday activities
- maintain our body temperature & condition of our body tissues
- grow
So therefore, we depend on plants for our energy source. Energy is still used by the body when we are sleeping or resting, to perform such tasks as keeping our involuntary breathing working and our heart beating. There are 2 types of energy needed by the body Rest Energy and Work Energy
Work Energy
- Is the energy required to carry out activities such as walking, running, swimming, growing
- The more physically active a person is, the more energy they require
Rest Energy
- Known as our Basal Metabolic Rate (BMR).
- It is defined as the amount of energy needed when lying completely at rest to maintain body temperature and keep the body alive
- It is interesting to note that the BMR of the population in a cold climate is usually about 10% higher than that of the population of people in warm countries.
- This is the explanation as to why some people can eat a lot and not put on weight, whereas others can put on weight even if they don't eat as much food
Factors Determining our Energy Requirements
- Gender - Males require a higher energy intake than females of the same age & amount of activity because the male body has a higher ratio of muscle to fat than the female body
- Age -Young children & teenagers are more active than the elderly so require more energy.
- Activity - The more physically active you are, the more energy you require.
- Body Size - a taller more lean body will require more energy than a fatter, smaller body
- Pregnant & Breast - Feeding - women require more energy during this stage of life, for the growth of the foetus and to maintain milk supply.
Amount of Kilocalories needed
These are estimated average requirements
Teenage Boy 2,900
Teenage Girl 2,300
Adult female Moderately active 2,150
Adult Female very active 2,500
Adult female (over 75) sedentary 1,680
Adult male (18 - 34) sedentary 2,510
Adult male (18 - 34) moderately active 2,900
Adult male (18 - 34) very active 3,350
Energy Balance
- If more kilocalories are consumed than the RDA for our particular group, the extra that are eaten will be converted into fat an stored under the skin as adipose tissue.
- To maintain a constant and satisfactory body weight our energy out put should = energy intake
- To reduce weight, energy intake should be reduced and energy output should be increased.
- Exercise is vitally important in the control of weight and the prevention of obesity
- The most effective way to lose weight is to cut down on high kilocalorie foods and increase exercise.
