The Science of Weight Loss
One pound of fat equals approximately 3,500 calories. To lose 1 lb/week, you need a 500-calorie daily deficit (500 × 7 = 3,500). This can come from eating less, exercising more, or a combination of both. The calculator computes your TDEE and subtracts the deficit needed to reach your selected weekly loss rate.
Safe Weight Loss Rates
| Rate | Daily Deficit | Sustainability |
|---|---|---|
| 0.5 lbs/week | −250 cal/day | Very sustainable |
| 1 lb/week | −500 cal/day | Recommended |
| 1.5 lbs/week | −750 cal/day | Moderate |
| 2 lbs/week | −1,000 cal/day | Aggressive, short-term |