Calorie Deficit Calculator

How calorie deficit is calculated

The calorie deficit model is based on the widely used approximation that 1 pound of body fat contains approximately 3,500 calories. This means a daily deficit of 500 calories produces roughly 1 pound of fat loss per week.

Note: The 3,500 calorie model is a useful approximation, not a precise biological law. Actual fat loss rates vary with individual metabolism, water retention, hormonal factors, and adherence. Expect more loss in the first 1–2 weeks (water weight) and a plateau around weeks 8–12 as metabolism adapts.

Frequently Asked Questions

• What is a calorie deficit?
  A calorie deficit is when you eat fewer calories than your body burns in a day. If your TDEE is 2,500 calories and you eat 2,000, you are in a 500-calorie deficit. Over time, this forces your body to draw on stored fat, resulting in weight loss.
• How big should my calorie deficit be?
  A deficit of 300–500 calories per day produces sustainable loss of 0.5–1 lb per week without significant muscle loss. A 500–750 calorie deficit produces 1–1.5 lbs per week, which is the upper end recommended by most nutrition guidelines. Deficits above 1,000 calories per day increase the risk of muscle loss and nutritional deficiencies.
• How much weight can I lose in a month on a deficit?
  A 500-calorie daily deficit produces roughly 4 lbs per month. A 750-calorie deficit produces approximately 6 lbs per month. These are estimates; actual results vary with individual metabolism and adherence.
• Will a calorie deficit cause muscle loss?
  A moderate deficit with adequate protein intake (0.8–1g per lb of bodyweight) and resistance training minimises muscle loss. Large deficits over 1,000 calories per day significantly increase lean mass loss. Protein intake and strength training are the primary protectors of muscle during a deficit.