How it works

Your body burns calories even at rest — this is your basal metabolic rate (BMR). Multiplying BMR by an activity factor gives your TDEE, the total calories you burn in a day. To lose weight, most people aim for a modest deficit; to gain, a modest surplus.

These numbers are estimates. Individual needs vary, and rapid or extreme calorie restriction isn't recommended. Consult a dietitian or doctor before making big changes.