Understanding the Calorie Deficit Calculator
A calorie deficit — eating fewer calories than you burn — is the fundamental requirement for fat loss. This calculator shows the deficit you need to reach a target rate of weight loss, helping you set a pace that is effective without being unsustainable.
The math of fat loss
A pound of body fat stores roughly 3,500 calories, so a daily deficit of about 500 calories yields close to a pound of loss per week. Larger deficits speed things up but are harder to sustain and risk muscle loss. A moderate deficit, paired with adequate protein, keeps the weight you lose mostly fat.
Why slower is often better
Aggressive deficits can leave you tired, hungry, and prone to rebound eating. A gentler deficit preserves muscle and energy, fits into real life, and is far easier to maintain long enough to reach your goal. Sustainable loss of around 0.5 to 1% of body weight per week is a sensible target for most people.
Tips & things to know
- •A ~500 calorie daily deficit targets about 1 lb of loss per week.
- •Keep protein high to protect muscle while in a deficit.
- •Slower, sustainable deficits beat crash diets.