Know How Many Calories You Should Eat
To avoid gaining weight over time, you should aim to burn up as many calories through basic metabolic function and physical activity as you take in. To know whether you're on track, you need to be able to estimate how many calories you need based on your age, gender and level of physical activity.
The calorie ranges shown in the table allow for the needs of people of different ages. Adults need fewer calories at older ages.
Adapted from the American Heart Association: