Find out how many calories you burn in a day, and how many to eat to lose, keep or gain weight. Uses the Mifflin-St Jeor equation, a standard formula for adults.
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest, just keeping your organs running. The Mifflin-St Jeor equation is a widely used and well-tested formula: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5 for men, −161 for women. TDEE (Total Daily Energy Expenditure) multiplies BMR by your activity factor. This is your maintenance calorie level: eat at this level and your weight stays stable.
One pound of fat equals roughly 3,500 calories. A 500-calorie daily deficit creates about 1 pound of weight loss per week, the rate most dietitians recommend for sustainable fat loss without significant muscle loss. Going below 1,200 calories (women) or 1,500 calories (men) per day typically triggers metabolic adaptation and muscle catabolism, making weight loss harder over time, not easier.
Most people underestimate their activity level and therefore underestimate their TDEE. A sedentary office worker with a BMR of 1,500 (1.2 multiplier) needs 1,800 calories. The same person training 5 days a week (1.55 multiplier) needs about 2,325, a 525-calorie difference. Eating at "sedentary" TDEE when you're actually active leads to under-fueling, fatigue, and muscle loss. If you exercise regularly, be honest with yourself about the activity multiplier.