Calorie Deficit — Simplified

Short and sweet: to lose weight you need to eat fewer calories than your body uses. That “gap” is the calorie deficit. Do it smartly and you lose mostly fat — do it too aggressively and you risk muscle loss, slowed metabolism, and burnout.

How deficits work (quick)

Your body burns a certain number of calories each day (maintenance or TDEE). Eat less than that and your body taps stored energy (fat) to make up the difference — that’s weight loss.
Rough rule: 3,500 calories ≈ 1 pound of body fat. Use that only as a guideline, because metabolism adapts.

Safe rates to aim for

Aim for 0.5–2 lbs per week. Most people do best at ~0.5–1 lb/week for sustainable results.
That equals roughly a 10–25% calorie cut from maintenance, or about 250–750 kcal/day.
Avoid very low intakes: generally don’t go below ~1,200 kcal/day for women or ~1,500 kcal/day for men without professional supervision.

Sample math (easy method)

Estimate maintenance (quick guess): body weight (lbs) × 15 ≈ daily maintenance (very rough).
Pick a deficit: 500 kcal/day = ~1 lb/week (500 × 7 = 3,500). Examples:

Person A: 150 lbs × 15 = 2,250 kcal maintenance → minus 500 = 1,750 kcal/day → ≈1 lb/week.
Person B: 200 lbs × 15 = 3,000 kcal maintenance → minus 500 = 2,500 kcal/day → ≈ 1 lb/week.

Quick extras:

If you want a slightly faster pace (~1.5 lb/week), a 750 kcal/day cut: 3,000 − 750 = 2,250 kcal/day.
If aiming slower (~0.5 lb/week), a 250 kcal/day cut: 3,000 − 250 = 2,750 kcal/day.

Reminder: avoid very low intakes (generally <1,500 kcal/day for men or <1,200 kcal/day for women) without professional guidance.