The most common weight loss mistake isn't eating the wrong foods — it's not knowing how many calories to eat in the first place.
The Core Principle
One pound of body fat contains roughly 3,500 calories. To lose that pound, you need a cumulative calorie deficit of 3,500 calories over time.
In practice: - 250 cal/day deficit → ~0.25 kg (0.5 lb) per week - 500 cal/day deficit → ~0.5 kg (1 lb) per week - 750 cal/day deficit → ~0.75 kg (1.5 lb) per week - 1,000 cal/day deficit → ~1 kg (2 lb) per week (aggressive, risk of muscle loss)
Step-by-Step: Finding Your Calorie Target
Step 1: Calculate your TDEE (Total Daily Energy Expenditure)
Example: 35-year-old woman, 170cm, 70kg, lightly active - BMR ≈ 1,495 calories - TDEE ≈ 2,056 calories (× 1.375)
Step 2: Set a deficit based on your goal pace
- Lose ~0.5 kg/week → 2,056 − 500 = 1,556 calories/day
- Lose ~0.25 kg/week → 2,056 − 250 = 1,806 calories/day
Step 3: Set a minimum floor
Never eat below your BMR for extended periods. For this person, the floor is 1,495 calories.
Why "Eat Less, Move More" Fails
The simple math works in theory, but the human body adapts:
- Metabolic adaptation: When you eat less for several weeks, BMR drops by up to 15–25%. This is why weight loss slows down after the first few weeks even on the same diet.
- Muscle loss: Large deficits (750+ calories below TDEE) cause the body to break down muscle tissue for energy, lowering BMR further.
- Hunger hormones: Calorie restriction increases ghrelin (hunger hormone) and decreases leptin (satiety hormone), making it harder to maintain the deficit.
The Sustainable Approach
- Aim for 0.5–1% of body weight per week. Faster loss usually means more muscle loss.
- Prioritize protein. At 1.6–2.2g of protein per kg of body weight, you preserve significantly more muscle during a deficit.
- Build in diet breaks. A week at maintenance every 4–6 weeks can partially reverse metabolic adaptation.
- Don't ignore strength training. It signals the body to preserve muscle even in a calorie deficit.
What About Minimum Safe Calories?
Common guidelines: - Women: no less than 1,200 calories/day - Men: no less than 1,500 calories/day
These are rough floors — your actual minimum should be based on your BMR, not generic guidelines.
Use our free calorie calculator to find your personalized target based on your stats and goal.