Harvard Heart Letter

Ask the doctor: How many calories do I need?

Ask the doctor

How many calories do I need?

Q. How can I figure out how many calories I should take in every day?

A. Clinicians use several equations to calculate how many calories a person should eat each day to maintain a stable weight. The most precise ones include height, weight, age, sex, activity level, and stressors like an injury or disease. The simplest way to estimate your daily target for calories is to multiply your weight by:

  • 12 if you are sedentary (little or no exercise)

  • 13.5 if you are somewhat active (light exercise one to three days a week)

  • 15.5 if you are moderately active (moderate exercise like brisk walking three to five days a week)

  • 17 if you are very active (vigorous exercise or sports six to seven days a week)

  • 19 if you are highly active (daily vigorous exercise or sports and a physical job).

For example, a somewhat active woman who weighs 145 pounds needs about 1,950 calories a day (145 times 13.5) to keep a steady weight.

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