Health and Nutrition
Nutrition for Sports Performance
Energy from Food
The food we eat provides energy in the form of carbohydrate, fat, protein and alcohol, and the energy equivalents of these nutrients is shown in the table. It is more appropriate, perhaps to think of the energy supplied by a fixed amount of different foods, and this depends on the content of these nutrients, but also on the amount of water, fibre and other components that provide bulk but not energy. There is very good evidence that a high fat diet predisposes to obesity because it is much easier to eat a high energy diet when the fat content is high. Complex carbohydrate foods contain large amounts of indigestible fibre and usually also have a high water content.
Rather than thinking about the energy values of the different nutrients present in the foods that we eat, it is often more convenient to think about how much energy is provided by a fixed amount of different foods. The following table shows the energy values per 100 grams of some common foodstuffs. It is immediately obvious that the high fat foods (and alcohol) provide lots of calories. Many of these foods supply little in the way of vitamins and minerals. This means that people on an energy-restricted diet need to be especially careful to limit intake of these foods. Athletes training hard – the runner who covers 100 miles per week or more in training, for example – is different; because of the high energy needs, there is room in the diet for more of these high fat foods.
Energy from food
Energy means fuel for the body to work, rest and play: to walk, to run, to rest and recover all require energy. All our energy comes from the foods that we eat.
| Energy value of food components per gram: | |
| Fat |
37 kilojoules (9 kilocalories) |
| Protein |
17 kilojoules (4 kilocalories) |
| Carbohydrate |
16 kilojoules (4 kilocalories) |
| Alcohol |
29 kilojoules (7 kilocalories) |
Most pre-packed foods bought in a shop will have a label showing the amount of these nutrients and the energy value of the food
| Food |
Calories per 100g |
% energy from CHO |
Food portion for 100 g CHO |
| Bread |
235 | 79 | 203 |
| Rice | 138 | 84 | 323 |
| Pasta | 86 | 81 | 540 |
| Potato |
75 | 89 | 562 |
| Carrot | 24 | 77 | 2041 |
| Green beans | 25 | 48 | 3125 |
| Apple |
47 | 94 | 847 |
| Banana | 62 | 93 | 654 |
| Chocolate | 529 | 42 | 168 |
