Calorie Deficit Calculator

Use a TDEE calculator (like the Calorie Calculator on this site) that takes your age, sex, weight, height, and activity level as inputs. Your TDEE is the calorie intake at which your weight neither rises nor falls. You can also empirically estimate it by tracking your food intake for two weeks while your weight stays flat - that average intake is your TDEE.

Several mechanisms converge as you lose weight: (1) your TDEE falls because you are carrying less mass, so the same calorie intake produces a shrinking deficit; (2) adaptive thermogenesis reduces non-exercise activity and heat production; (3) the 3,500 kcal/lb rule overestimates later losses. Recalculate your TDEE at your new lower weight and adjust your target intake accordingly.

Yes. Beyond about 1-1.5% of body weight per week, muscle loss accelerates significantly and nutrient intake often falls below safe minimums. Rapid weight loss is also associated with gallstone formation. A slower, steady approach with adequate protein and strength training preserves lean mass and produces better body composition at the goal weight.

Your TDEE already includes an activity factor, so if you are using a TDEE-based calculation, exercise is accounted for. If you calculated maintenance as a sedentary BMR, then yes - you should account for exercise calories. Either way, calorie-burn estimates from wearables typically over-report by 15-30%, so eating back only 50-70% of estimated exercise calories is a safer approach. This calculator is for informational purposes only and does not constitute medical advice.