Meat and vegetables are measured in grams and kilograms. Milk and other liquid foods are measured in liters or milliliters. These units only measure quantity: they do not measure the value of the food to the body. The unit which measures the quality or value of food is the calorie the amount of heat given off by food when it brurns. This measurement tells how much energy a certain food has when it is completely used by the body.
Our bodies use varying（不同程度的） amount of calories. The more exercise we take, the more calories we burn. If we eat food which contains more calories than we use up, then it is possible that we would increase in weight. In order to avoid becoming overweight, it is advisable to eat a balanced diet and not eat too many foods that have a high calorie rating. The table below gives you some idea of the number of calories in food.
| A. Meats Slice of bacon 50 Hamburger 300 Slice of beef 100 Sausage 180 Meat pie 500 Sausage roll 350 | B.Fruits Apple 70 Orange 70 Pear 80 Banana 80 Plum 20 Tomato 20 | |
| C. Sweets and Pastries Small chocolate bar 190 Large chocolate bar 225 Slice apple pie 300 Doughnut 200 Scoop of ice cream 85 Bag of potato crisps 145 | D. Vegetables 60g carrots 18 60g potato 60 60g onion 25 60g cucumber 10 60g cabbage 15 |