Calorie Deficit for Weight Loss: A Complete, Evidence-Based Guide
Losing weight comes down to one simple principle: eat fewer calories than your body burns. But how many fewer is safe, sustainable, and effective? Here is how to calculate a calorie deficit grounded in TDEE, Mifflin-St Jeor, and CDC minimums.
Try it: Calorie Deficit Calculator
Enter your age, sex, weight, height, and activity — the calculator returns your TDEE, daily calorie target for weight loss, weekly loss rate, and macro split (protein, fat, carbs).
Calorie Deficit Calculator
How Calorie Deficit Works
Calculate BMR
Using the Mifflin-St Jeor equation based on weight, height, age, and gender.
Multiply by Activity
Your TDEE = BMR × activity factor. This is your maintenance calories.
Set Your Deficit
Subtract 500 cal/day to lose ~1 lb/week. A sustainable rate for most people.
The Science
One pound of body fat contains approximately 3,500 calories. A daily deficit of 500 calories creates a weekly deficit of 3,500 calories, resulting in about 1 pound of weight loss per week. This is considered a safe and sustainable rate by most health organizations.
The full calculator includes a goal-date projection and a safe-deficit range based on CDC minimums (1,200 cal women, 1,500 cal men).
Open the full health calculatorWhat Is a Calorie Deficit?
A calorie deficit means consuming fewer calories than your body needs to maintain its current weight. One pound of body fat equals approximately 3,500 calories (per the original Wishnofsky 1958 paper that is still the standard medical reference). To lose 1 pound per week, you need a daily deficit of about 500 calories.
Daily Calories for Weight Loss = TDEE − Deficit
Example: TDEE of 2,200 − 500 deficit = 1,700 calories/day = ~1 lb/week loss
The 3,500-calories-per-pound rule is an approximation. Recent research (Hall et al., 2011) shows actual weight loss adapts over time — a 500 cal/day deficit produces slightly less than 1 lb/week after the first few months because the body lowers its metabolic rate. Real-world weight-loss plateaus are part of this adaptation, which is why the calculator below uses a slightly more conservative model.
Calculate Your TDEE (Total Daily Energy Expenditure)
TDEE is the total number of calories your body burns per day, including exercise. It is calculated using the Mifflin-St Jeor equation (1990), which the American Dietetic Association considers the most accurate for non-hospitalized adults:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Then: TDEE = BMR × Activity Multiplier
| Activity Level | Multiplier |
|---|---|
| Sedentary (little/no exercise) | 1.2 |
| Light (1-3 days/week) | 1.375 |
| Moderate (3-5 days/week) | 1.55 |
| Active (6-7 days/week) | 1.725 |
| Very Active (hard exercise daily) | 1.9 |
How Big Should Your Deficit Be?
| Deficit | Weekly Loss | Difficulty |
|---|---|---|
| 250 cal/day | 0.5 lb (0.2 kg) | Easy |
| 500 cal/day | 1 lb (0.45 kg) | Moderate (Recommended) |
| 750 cal/day | 1.5 lb (0.7 kg) | Challenging |
| 1,000 cal/day | 2 lb (0.9 kg) | Aggressive (Max) |
Most experts recommend a deficit of 500-750 calories per day. Going below 1,200 calories/day for women or 1,500 calories/day for men (CDC minimums) should only be done under medical supervision, because it is hard to meet micronutrient needs at very low intakes and muscle loss accelerates.
Macro Breakdown in a Calorie Deficit
When cutting calories, maintaining adequate protein is crucial to preserve lean muscle mass and keep satiety high:
- Protein: 0.7-1.0 grams per pound of body weight per day (30-35% of calories). Higher end (1.0 g/lb) for resistance trainers.
- Fat: 0.3-0.4 grams per pound (25-30% of calories). Avoid going below 0.3 g/lb — fat is needed for hormone production.
- Carbs: Remaining calories (35-45%). Lower end on keto, higher end on endurance-focused training.
Example split for a 1,700 calorie target at 150 lb body weight: 130 g protein (520 cal) + 50 g fat (450 cal) + 180 g carbs (720 cal).
Common Pitfalls
- Underestimating calorie intake — most people eat 20-40% more than they think. Use a food scale and tracking app for the first 4-6 weeks.
- Overestimating exercise calories — fitness trackers typically overcount by 30-50%. Eat back at most 50% of what your tracker says you burned.
- Going too aggressive — deficits over 1,000 cal/day increase muscle loss and trigger metabolic adaptation.
- Ignoring sleep and stress — poor sleep raises ghrelin (hunger hormone) and lowers leptin (satiety hormone), sabotaging the deficit.
Key Takeaways
- Calculate your TDEE first using Mifflin-St Jeor, then subtract 500-750 calories
- Aim for 1-2 pounds per week for sustainable loss — the CDC-recommended safe range
- Keep protein at 0.7-1.0 g per pound to preserve muscle mass and satiety
- Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision
- Use our Calorie Deficit Calculator for a personalized plan with TDEE, macros, and goal-date projection
About this guide
Methodology: TDEE via Mifflin-St Jeor (1990) with the 5-level activity multiplier. Calorie deficit target uses 500-750 cal/day per CDC safe-rate guidance; minimum 1,200 cal women / 1,500 cal men. Weight loss uses the 3,500 cal/lb approximation with the Hall et al. (2011) adaptation model for >12-week projections. Reviewed by the Jonathan Reed (Master of Applied Mathematics) on October 9, 2026.