How Many Calories Do I Need?

Have you ever wondered just how many calories your body really needs? Well, you can't know exactly, but there is a formula you can use to get a very close estimate.

The formula is called the Harris Benedict Equation. It gives you an idea of your resting calorie needs, or in other words, your basal metabolic rate (BMR). I'm sure many of you have tried losing weight before and wondered how to eat enough to have energy to exercise and not be starving all day!

Well, let's plug in some numbers to help you determine how many calories your body actually needs. This formula tells you what your resting calorie needs are:

Women: 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years) = BMR

Men: 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years) = BMR

Then follow up with the following formula to add in your physical activity. Multiply your determined BMR and the appropriate activity factor:

  1. If you are sedentary (little or no exercise): BMR x 1.2
  2. If you are lightly active (light exercise/sports 1–3 days a week): BMR x 1.375
  3. If you are moderatetely active (moderate exercise/sports 3–5 days a week): BMR x 1.55
  4. If you are very active (hard exercise/sports 6–7 days a week): BMR x 1.725
  5. If you are extra active (very hard exercise/sports and physical job or 2x training): BMR x 1.9


To determine how many calories you are consuming, keep a food journal. Record your food intake for a few days, and then take an average. (Remember to multiply the calories by how many serving sizes you are having of that food.)

Now you know how many calories you need to eat to keep your weight steady (by the results of the formula) as well as how many calories you are currently eating. A pound of fat equals 3,500 calories.  So, in order to lose 1 pound of fat a week, you need a calorie deficit of 500 calories a day (ideally from a combination of exercise and food). With a 500-calorie deficit every day, you should lose about 1 pound a week.  While that's a small amount, you won't be as hungry as more-aggressive plans and will be less likely to abandon the plan.

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