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How many calories should you eat to lose weight? Enter your details for your TDEE and a daily target at your chosen pace — plus a trial-grounded look at how much easier a GLP‑1 makes holding the deficit.
Enter your age, height, and weight above to see your BMR, maintenance calories, and a GLP-1 weight-loss projection.
BMR uses the Mifflin-St Jeor equation. Estimates are general nutrition information, not medical or dietary advice. Inputs stay on your device — nothing is sent anywhere.
To lose weight you must eat fewer calories than you burn — a calorie deficit. Your daily burn is your TDEE (resting metabolism × an activity factor), which the calculator above computes with the Mifflin-St Jeor equation. Eat below it and your body draws on stored fat. The old rule of thumb is that ~3,500 calories equals about a pound of fat, so a 500-calorie daily deficit loses roughly a pound a week.
That rule is a useful starting point, not a law — real loss varies with water, muscle, and hormones. And every deficit shrinks over time: as you get lighter you burn fewer calories, and adaptive thermogenesis nudges your metabolism down. That is why weight loss stalls even when you are "doing everything right." The fix is to recalculate your TDEE at your new weight every few weeks and re-set the target.
The math is simple; the hunger is not. A deficit makes your body defend its weight by ramping up appetite hormones — which is why willpower-only diets so often rebound. GLP-1 medications (semaglutide as Wegovy, tirzepatide as Zepbound) work on exactly this problem: they blunt appetite so the same deficit feels effortless. In trials, that produced about 15% (Wegovy) to 21% (Zepbound) average total weight loss. They do not change your calorie math — they make it stick.
Want maintenance calories instead of a deficit? Use the TDEE calculator. To hold muscle while you cut, see high-protein foods and the week-by-week GLP-1 projection.