Calorie Deficit Calculator

A calorie deficit occurs when you consume fewer calories than your body burns (TDEE). Your body then uses stored energy (fat and glycogen) to make up the difference, resulting in weight loss. A deficit of 3,500 calories roughly equals 1 pound of fat loss.

A moderate deficit of 500 calories per day (3,500/week) leads to about 1 pound of weight loss per week. A 250-calorie deficit is gentler and more sustainable. Deficits larger than 1,000 calories/day are not recommended without medical supervision as they can cause muscle loss and metabolic adaptation.

A 1,000 calorie deficit can be safe for some people in the short term but is aggressive. It may lead to muscle loss, nutrient deficiencies, fatigue, and metabolic slowdown. Most experts recommend a 500-calorie deficit for sustainable, healthy weight loss of 1 lb/week.

Common reasons include: underestimating calorie intake, overestimating exercise calories burned, metabolic adaptation from prolonged dieting, water retention (especially in women), building muscle while losing fat, or medical conditions affecting metabolism. Try tracking food more accurately for 2 weeks.