What Is A Calorie Deficit?
A calorie deficit means consuming fewer calories than your body burns in a day. When your body doesn't get enough energy from food, it turns to stored fat as a fuel source, which is how fat loss happens. The size of your deficit determines how fast you lose fat.
Your starting point is always your TDEE, the total calories you burn daily. Subtract your chosen deficit from that and you have your daily calorie target.
How Big Should Your Deficit Be?
Research consistently supports a 500 kcal/day deficit as the sweet spot for most people. This produces roughly 0.5kg of fat loss per week, a rate that's sustainable, preserves muscle, and doesn't require dramatic willpower. More aggressive deficits are possible but come with trade-offs.
| Deficit Size | Weekly Loss | Best For | Risk |
|---|---|---|---|
| -250 kcal | ~0.25 kg | Athletes, muscle retention priority | Minimal |
| -500 kcal | ~0.5 kg | Most people, recommended | Low |
| -750 kcal | ~0.75 kg | Higher body fat, shorter phases | Moderate |
| -1000 kcal | ~1 kg | Short-term only | High |
The Minimum Calorie Floor
There's a lower limit to how far you should take your deficit. Going below 1,200 kcal/day for women or 1,500 kcal/day for men typically results in muscle loss, hormonal disruption, fatigue and metabolic slowdown. If your calculated target falls below these thresholds, increase your activity level rather than cutting calories further.
What To Do When Fat Loss Stalls
Fat loss rarely moves in a straight line. After 4-6 weeks at the same deficit your body adapts, your TDEE decreases as you lose weight. When this happens, recalculate your TDEE at your new bodyweight and adjust your target. Don't cut calories drastically, recalibrate from your updated maintenance figure.
Before cutting more calories, check your tracking accuracy. Studies show people consistently underestimate their food intake by 20-30%. Track every bite for a week, weighing your food with a scale, before concluding that you need a bigger deficit.
