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Diet and exercise


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Regular exercise and a balanced diet are needed to keep the body healthy. Too little food leads to a person being underweight and prone to certain types of illness, while too much food and not enough exercise leads to a person being overweight and other types of ill health.


A mixture of different types of food in the correct amounts is needed to maintain health.

The main food groups are carbohydrates, fats and proteins.

This table summarises some typical sources of these nutrients and why our bodies need them.

The main food groups

Food groupFound inNeeded by our bodies for:

potato, banana, pasta

potatoes, pasta, bread, bananas, sugar and ricea source of energy for life processes


cheese, butter, margarine and oilsa source of energy for life processes: fats are also needed to make cell membranes and to insulate our bodies


meat, fish, eggs and cheesegrowth and repair - building cells

Mineral ions and vitaminsvitamins: organic substances which are essential in small amounts to regulate the metabolism and maintain the immune system are also important in a healthy diet. They are needed in small amounts for healthy functioning of the body.

Imbalanced diets

An imbalanced diet causes a person to become malnourished. For example:

  • too little food may lead to a person being underweight
  • too much food may lead to a person being overweight.

A poor diet may also lead to deficiency diseases. For example, too little vitamin D in the diet can lead to rickets, which affects the proper growth of the skeleton. Type 2 diabetes is also a problem related to poor diet. Note that you do not need to know how the nutrients work or the effects of any particular deficiency in the diet for your exam.


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