How many calories do you need each day to reach your goal weight? It depends on several factors including your age, body size, and activity level. But your needs are easy to figure once you know a little calorie math.
A pound of fat contains approximately 3,500 calories (about the same number as in a pound of butter or margarine). Figure the calorie math this way: If you eat 3,500 fewer calories than your body uses, you will shed about 1 pound.
Take in 7,000 fewer calories -- or, use up 7,000 extra calories -- and you will lose about 2 pounds. (Of course, this is over a period of time. Nutrition experts say losing one-half to 1 pound a week at most is the safest, most effective way to take off pounds and keep them off.)
How does this translate into everyday living? By eating 500 fewer calories each day, you should lose about 1 pound a week. Or cut only 250 calories each day and lose one-half pound a week.
Use the steps below to estimate the calories you need each day to lose about 1 pound per week.
1. Determine the calories you burn per pound each day based on your average level of activity:
- 13 calories/pound for inactivity (office work/sitting most of the day)
- 15 calories/pound for moderate activity (office work plus 30 to 60 minutes of aerobic activity, or walking/standing most of the day)
- 17 calories/pound for extensive activity (strenuous physical work or athletic level of physical activity)
2. Multiply the calories you burn per pound from Step 1 by your current weight in pounds to estimate your daily calorie needs.
3. Subtract 500 calories from your daily calorie needs in Step 2 to determine the number of calories you need to lose 1 pound per week. Create a daily deficit of 500 calories per day by eating fewer calories, burning off extra calories with physical activity, or, best yet, doing both.
So if you're a moderately active 133-pound woman, you need 15 calories times 133, or about 1,995 calories per day for your weight to stay the same. To lose 1 pound in a week, create a deficit of 500 calories each day. You can do this in different ways. For example, each day you could eat 400 fewer calories and burn off 100 extra calories with physical activity, or eat 300 fewer calories and burn off 200 extra calories. Whatever the combination, the choice is yours.