A calorie deficit occurs when you consume fewer calories than your body burns (TDEE). It forces your body to use stored energy (fat) for fuel, resulting in weight loss. A deficit of 3,500 calories corresponds to approximately 1 pound of fat lost.
Calorie Deficit = TDEE − Daily Calorie Intake
TDEE = BMR × Activity Multiplier
TDEE = Total Daily Energy Expenditure (total calories burned per day). BMR = Basal Metabolic Rate (calories burned at complete rest). Activity Multiplier ranges from 1.2 (sedentary) to 1.9 (very active). A 500 calorie/day deficit yields approximately 1 lb/week of weight loss.
Example 1: Female, 30 years old, 140 lbs (63.5 kg), 5'5" (165 cm), moderately active (3-5 days/week exercise)
Result: Eat 1,600 calories/day for ~1 lb/week weight loss
Example 2: Male, 25 years old, 200 lbs (90.7 kg), 6'0" (183 cm), lightly active (1-3 days/week)
Result: Eat 2,155 calories/day for ~1 lb/week weight loss
Use our free Calorie Deficit Calculator to skip the manual math.
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