Calorie Deficit Calculator: Your Weight Loss Calorie Target
To lose 1 lb per week, a 30-year-old male (5'10", 175 lbs, moderate activity) needs a 500-calorie deficit: eat 2,228 calories instead of his 2,728 TDEE. At this rate, he would reach 160 lbs in approximately 15 weeks. A 250-calorie deficit is more sustainable at 0.5 lb/week.
Calculate Your Calorie Deficit
Find your safe calorie target for weight loss.
Your Daily Target
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calories/day for weight loss
Deficit Levels and Expected Results
| Deficit | Calories Below TDEE | Weekly Loss | Sustainability | Risk |
|---|---|---|---|---|
| Conservative | -250 cal/day | ~0.5 lb/week | Very high | Very low |
| Moderate | -500 cal/day | ~1 lb/week | High | Low |
| Aggressive | -750 cal/day | ~1.5 lbs/week | Medium | Medium |
| Very Aggressive | -1,000 cal/day | ~2 lbs/week | Low | High |
The Safe Minimum
Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision. Very low calorie diets (under 800 cal/day) should only be undertaken with a physician's guidance.
Protecting Muscle During a Deficit
A calorie deficit causes your body to burn stored energy — but it does not distinguish between fat and muscle. To maximize fat loss while preserving muscle:
1. Eat adequate protein — 0.8-1.0g per pound of body weight
2. Strength train 2-4x per week (muscle receives a "keep this" signal)
3. Keep deficit moderate — deficits over 25% of TDEE increase muscle loss risk
4. Sleep 7-9 hours — insufficient sleep increases muscle catabolism by up to 60% (Nedeltcheva et al., 2010)
5. Avoid cardio-only approaches — excessive cardio without resistance training accelerates muscle loss
Sources
Frequently Asked Questions
What is a calorie deficit?
A calorie deficit occurs when you eat fewer calories than your body burns (your TDEE). This forces your body to use stored energy — primarily body fat — to make up the difference. A deficit of 3,500 calories is roughly equivalent to 1 pound of fat loss, though this number is an approximation that varies by individual.
How big should my calorie deficit be?
For most people, a deficit of 300-500 calories per day (moderate) is optimal. This produces 0.5-1 lb of weight loss per week while being sustainable and minimizing muscle loss. Larger deficits (750-1,000 cal) may be appropriate for people with a higher body fat percentage but become increasingly difficult to maintain.
Why am I not losing weight in a calorie deficit?
Common reasons: (1) Underestimating food intake — studies show people underreport calories by 30-50% on average, (2) Overestimating activity level, (3) Water retention masking fat loss (common in early weeks and around menstrual cycles), (4) Metabolic adaptation after prolonged dieting, (5) Measurement error. Track accurately for 2 full weeks before troubleshooting.
Can I lose weight without counting calories?
Yes. A calorie deficit can be achieved without counting by eating more protein and fiber (both increase satiety), reducing ultra-processed foods, eating slowly, using smaller plates, and following time-restricted eating patterns. Calorie counting is the most precise method, but not the only path to a deficit.
Will my metabolism slow down in a deficit?
Yes, to some degree. Metabolic adaptation (adaptive thermogenesis) causes your body to burn 5-15% fewer calories than predicted after sustained dieting. Strategies to minimize this include periodic diet breaks (1-2 weeks at maintenance every 8-12 weeks), maintaining strength training, keeping protein high, and avoiding extremely large deficits.