Calories add up to pounds. So one way to watch your weight is to determine how many calories you should eat each day.

The following formula is designed to produce weight loss of approximately 2 pounds per week--a safe amount that's most likely to stay off.

1. Determine your goal weight (see the desirable weights table.)

2. Multiply that figure by 9 if you are moderately active. (That is, if you bicycle, walk, swim, or participate in similar activities three or more times a week.) If you are more active than average, (that is, if you participate in aerobic dance, circuit weight training, racquetball, jogging, or other vigorous activities three or more times a week or work at a physically demanding job) multiply by 10. If you are fairly inactive, tend to lose weight slowly, or are over age 45, multiply by 8. (If you rarely, if ever, do anything more strenuous than sewing, reading, or playing cards, you are inactive.)

3. Round off the total to the nearest 100 calories. For example: Desirable weight = 130 pounds; activity level = 9 (moderately active); 130 x 9 = 1,170 calories, which, when rounded off, equals 1,200 calories per day.

4. To figure out how many calories a week you should be consuming, multiply the daily total by 7. It's more realistic and practical to try to average a certain number of calories per week than to try to hit an exact number per day, because we all have days when we eat more--or less--than average.