How do I calculate my calorie deficit for weight loss?

First, calculate your TDEE using the Mifflin-St Jeor equation: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age ± 161, then multiply by activity factor (1.2-1.9). For sustainable weight loss, subtract 500-750 calories from your TDEE. This creates a deficit that results in 0.5-0.75 kg weight loss per week. Track your actual intake for 2 weeks and adjust based on real results, as calculators have 10-15% variance from individual metabolism.

Is a 500 calorie deficit enough to lose weight?

Yes, a 500 calorie daily deficit is the gold standard for sustainable weight loss. It results in approximately 0.5 kg (1 lb) weight loss per week — slow enough to preserve muscle and avoid metabolic adaptation, fast enough to see meaningful results. Over 20 weeks, you'd lose 10 kg. This deficit size works because it's large enough for progress but small enough to maintain without extreme hunger or nutrient deficiencies.

What happens if my calorie deficit is too large?

Deficits over 1000 calories (or eating below BMR) cause: muscle loss (body breaks down muscle tissue for energy), metabolic slowdown (BMR drops 15-30% making future weight loss harder), increased hunger and cravings (triggering binge eating cycles), nutrient deficiencies (hard to get adequate protein, vitamins on very low calories), and potential health issues (fatigue, hair loss, weakened immunity). The safe minimum is 1200 cal for women, 1500 cal for men, or your BMR.

How many calories should I cut to lose 1 kg per week?

To lose 1 kg per week, you need a deficit of approximately 1000 calories per day (1 kg fat ≈ 7700 calories). However, this aggressive deficit is not recommended for most people because it risks muscle loss, metabolic damage, and is difficult to sustain. A safer approach is 500-750 cal deficit for 0.5-0.75 kg weekly loss, combined with exercise to preserve muscle. Fast weight loss often leads to weight regain.

Why am I not losing weight in a calorie deficit?

Common reasons: (1) Underestimating intake — studies show people track 40-60% wrong, missing hidden calories like cooking oil and sauces; (2) Overestimating activity — 'moderately active' requires intentional exercise 3-5x/week, not just daily movement; (3) Metabolic adaptation — BMR drops 5-15% after weeks of deficit; (4) Not adjusting — as weight decreases, TDEE decreases, requiring recalulation; (5) Water weight fluctuations masking fat loss. Use AI tracking like CalorieAI to reduce tracking errors and see true intake.

Can I create a calorie deficit by exercise only?

Yes, but it requires significant exercise volume. Burning 500 extra calories daily needs: 45-60 min jogging, 60-90 min brisk walking, or 30 min HIIT — every day. For most people, combining moderate exercise (200-300 cal) with moderate food reduction (200-300 cal) is more sustainable. Exercise-only deficits work better for those who enjoy daily activity and can't reduce food intake due to hunger sensitivity.

Calorie Deficit Calculator: How Many Calories Should You Cut to Lose Weight?

Want to lose weight? You need a calorie deficit.

It's the fundamental law of weight loss: burn more calories than you eat. But how big should your deficit be? How do you calculate it? And how do you track it without spending hours logging food?

What Is a Calorie Deficit?

A calorie deficit means consuming fewer calories than your body burns. When you're in a deficit, your body uses stored fat for energy — resulting in weight loss.

The math is simple:

Calorie Deficit = Calories Burned (TDEE) - Calories Consumed

If you burn 2000 calories per day and eat 1500, you're in a 500-calorie deficit.

How Many Calories to Lose Weight?

The size of your deficit determines how fast you lose:

Daily Deficit	Weekly Weight Loss	Time to Lose 10 kg	Sustainability
250 calories	0.25 kg (0.5 lbs)	40 weeks	★★★★★ Very sustainable
500 calories	0.5 kg (1 lb)	20 weeks	★★★★☆ Recommended
750 calories	0.75 kg (1.5 lbs)	13 weeks	★★★☆☆ Short-term only
1000 calories	1 kg (2 lbs)	10 weeks	★★☆☆☆ Risky, not advised

Scientific consensus: A 500-750 calorie deficit is optimal for most people. It's large enough to see results, small enough to maintain long-term.

Calorie Deficit Calculator: Step-by-Step

Step 1: Calculate Your TDEE (Total Daily Energy Expenditure)

Your TDEE is the total calories you burn daily. Use the Mifflin-St Jeor equation:

For men:

TDEE = (10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5) × activity multiplier

For women:

TDEE = (10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161) × activity multiplier

Activity multipliers:

Sedentary (desk job, little exercise): × 1.2
Lightly active (1-3 workouts/week): × 1.375
Moderately active (3-5 workouts/week): × 1.55
Very active (6-7 workouts/week): × 1.725
Extra active (physical job + training): × 1.9

Step 2: Choose Your Deficit Size

Based on your goals and timeline:

Slow & sustainable: TDEE - 250 (lose 0.25 kg/week)
Standard weight loss: TDEE - 500 (lose 0.5 kg/week)
Faster results: TDEE - 750 (lose 0.75 kg/week)
Maximum safe: Never below your BMR (Basal Metabolic Rate)

Step 3: Example Calculation

Example: 30-year-old woman, 65 kg, 165 cm, moderately active

Step 1 - BMR:

10 × 65 + 6.25 × 165 - 5 × 30 - 161 = 650 + 1031 - 150 - 161 = 1370 calories

Step 2 - TDEE:

1370 × 1.55 = 2118 calories/day

Step 3 - Weight loss target:

2118 - 500 = 1618 calories/day

Her calorie target: 1600-1650 calories per day for steady 0.5 kg/week weight loss.

Calorie Deficit Calculator Quick Reference

Your TDEE	Mild Deficit (250)	Standard (500)	Faster (750)
1500 cal	1250 cal	1000 cal (too low)	750 cal (unsafe)
1800 cal	1550 cal	1300 cal	1050 cal (risky)
2000 cal	1750 cal	1500 cal	1250 cal
2200 cal	1950 cal	1700 cal	1450 cal
2500 cal	2250 cal	2000 cal	1750 cal
2800 cal	2550 cal	2300 cal	2050 cal

Warning: Never eat below 1200 calories (women) or 1500 calories (men) without medical supervision. Below these thresholds, you risk nutrient deficiencies, muscle loss, and metabolic damage.

Why Most Calorie Deficits Fail

Reason 1: Calculating TDEE Wrong

Most people overestimate their activity level. "I walk to work" ≠ moderately active. True moderate activity means 45-60 minutes of intentional exercise 3-5 times per week.

Solution: Use the lower activity multiplier if unsure. Sedentary or lightly active is safer for most office workers.

Reason 2: Not Tracking Accurately

Studies show people underestimate calorie intake by 40-60%. Common errors:

Portion sizes: "Medium" is subjective — could be 200 or 400 calories
Hidden calories: Cooking oil (120 cal/tbsp), salad dressing (100+ cal), sauces
Forgotten items: That morning latte (150 cal), handful of nuts (200 cal)
Restaurant meals: Generic database entries are 30-50% off

Solution: Use AI photo tracking. CalorieAI analyzes your actual food visually, eliminating guesswork. Accuracy improves from 40-60% error to 10-15%.

Reason 3: Deficit Too Large

Aggressive deficits (1000+ calories) cause:

Muscle loss: Body breaks down muscle for energy, not just fat
Metabolic slowdown: BMR drops 15-30%, making future weight loss harder
Hunger & cravings: Extreme deficits trigger binge eating
Nutrient deficiencies: Hard to get enough protein, vitamins on 1200 cal

Solution: Stick to 500-750 calorie deficit. Add exercise to increase TDEE rather than cutting food further.

Reason 4: Not Adjusting Over Time

As you lose weight, your TDEE decreases:

5 kg lost → TDEE drops ~50 cal/day
10 kg lost → TDEE drops ~100 cal/day
20 kg lost → TDEE drops ~200 cal/day

If you don't adjust your target, your deficit shrinks and weight loss stalls.

Solution: Recalculate your TDEE every 5 kg of weight change.

How to Create Your Deficit Without Starving

Option A: Eat Less (Calorie Reduction)

The simplest approach: reduce intake by your deficit amount.

Cut 500 cal/day: Remove one large snack, reduce portions, skip dessert
Easiest targets: Drinks (soda, juice, alcohol), snacks, second portions
Keep protein high: 1.6-2.2g per kg to preserve muscle

Option B: Move More (Increase TDEE)

Burn more without eating less:

Add 500 cal exercise: 45-60 min jogging, 60-90 min brisk walking, 30 min HIIT
NEAT (Non-Exercise Activity): Take stairs, park farther, stand more
Strength training: Builds muscle, increases resting metabolism

Option C: Combine Both (Best Results)

Research shows combining diet + exercise works best:

Reduce intake by 300 cal: Smaller portions, fewer snacks
Add 200 cal exercise: 30 min daily walk
Total deficit: 500 cal/day with less hunger

Track Your Deficit with AI

Creating a deficit requires tracking. But manual tracking fails because:

It takes 10-15 minutes per meal
Portion guesses are 40-60% wrong
Restaurant meals have no accurate database entries

CalorieAI solves this with photo recognition:

3-second capture: Snap a photo before eating
85%+ accuracy: Visual analysis beats manual guessing
Asian food specialist: Recognizes dishes other apps can't
Daily dashboard: See your deficit vs. target instantly

Try CalorieAI free — no credit card required.

Get Pro for unlimited tracking and personalized deficit recommendations.