Weight Loss — TDEE, BMR, Calorie Deficit
3,500 cal/lb. Mifflin-St Jeor BMR. Safe 1–2 lb/week. 10–15% metabolic adaptation. 25% muscle loss risk at aggressive deficits.
Why This Stat Matters
Why: Sustainable deficit = 500–1000 cal/day for 1–2 lb/week. Metabolic adaptation reduces TDEE 10–15%. Preserve muscle with adequate protein.
How: Enter current/goal weight, height, age, gender, activity. Get BMR, TDEE, target calories, macros. Optional custom target.
- ●3,500 cal = 1 lb fat; 500 cal/day deficit = 1 lb/week
- ●10–15% metabolic adaptation with prolonged deficit
- ●25% of weight loss can be muscle at aggressive deficits
Weight Loss Calculator
3,500 cal/lb • 1–2 lb/week safe • 10–15% metabolic adaptation • 25% muscle loss risk.
Examples
Screenshot Summary
TDEE 2724 • Target 2224 cal • Deficit 500 cal/day • P136g C294g F56g
Milestone Tracker
⚠️For educational and informational purposes only. Verify with a qualified professional.
🏅 Sports Records
3,500 cal deficit = 1 lb fat loss
Safe rate: 1–2 lb/week
25% muscle loss risk at aggressive deficits
Answer Capsule: 1 lb fat ≈ 3,500 calories deficit. Safe loss: 1–2 lbs/week = 500–1000 cal/day deficit. Metabolic adaptation reduces TDEE 10–15%. Muscle loss ~25% without resistance training. Hall (2008): dynamic models more accurate than 3,500 rule.
Key Takeaways
- 1 lb fat = 3,500 calories deficit. Safe: 1–2 lbs/week (500–1000 cal/day)
- TDEE = BMR × activity. BMR: Mifflin-St Jeor. Metabolic adaptation: 10–15% TDEE drop
- Do not go below 1200 cal/day (women) or 1500 cal/day (men) without medical supervision
- ~25% of weight loss can be muscle without resistance training
Did You Know?
How It Works
BMR from Mifflin-St Jeor. TDEE = BMR × activity multiplier. Deficit = TDEE − target calories. 3,500 cal deficit ≈ 1 lb fat loss. Timeline = (lbs to lose × 3500) ÷ (daily deficit × 7).
Macros: protein 0.8–1g/lb goal weight to preserve muscle. Remaining calories split between carbs and fat. Metabolic adaptation means actual loss may slow over time.
Expert Tips
1–2 lbs/week is safe. Faster = more muscle loss, metabolic adaptation
Add resistance training to minimize the ~25% muscle loss
Expect 10–15% TDEE drop during long diets—adjust intake
Never below 1200 (F) or 1500 (M) cal without medical oversight
Comparison Table
| Deficit | Loss/Week | 10 lb timeline |
|---|---|---|
| 250 cal/day | ~0.5 lb | ~20 weeks |
| 500 cal/day | ~1 lb | ~10 weeks |
| 750 cal/day | ~1.5 lb | ~7 weeks |
| 1000 cal/day | ~2 lb | ~5 weeks |
Infographic Stats
Official Sources
Disclaimer: This calculator is for educational purposes. Consult a healthcare provider before starting any weight loss plan. Severe calorie restriction can harm health. Metabolic adaptation and individual variation affect results.