1. We need calories to do the things every day.
2. For example, when we walk to school or ride a bike to school, we spend a certain amount of energy.
3. It's difficult for us to calculate how many calories should we have.
4. If people want to keep in shape, they should remember that everyone should have between 1600 and 2500 calories a day.
5. We get calories from the food we eat.
6. If we get too much food and don't take part in any activities, we can get fat quickly.
7. So besides studying, we should do some exercises, play sports, or do the housework, such as cleaning the floor, cooking, etc.
8. Otherwise, if we don't eat enough, we will be tired and weak.
9. It's important to stay hydrated, so we should drink enough water.
10. To stay healthy, we need to stay active and make sure we have enough calories.