The core principle: calories in vs calories out
Weight loss comes down to one equation: consume fewer calories than your body burns. One pound of body fat stores approximately 3,500 calories. So a 500-calorie daily deficit creates roughly 1 pound of fat loss per week.
Step 1 — Find your TDEE
The most accurate BMR formula is the Mifflin-St Jeor equation:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Then multiply your BMR by your activity level:
- Sedentary (desk job, no exercise): BMR × 1.2
- Lightly active (1–3 days exercise/week): BMR × 1.375
- Moderately active (3–5 days/week): BMR × 1.55
- Very active (6–7 days/week): BMR × 1.725
Step 2 — Set your deficit
- Lose 0.5 lb/week: TDEE minus 250 calories/day
- Lose 1 lb/week: TDEE minus 500 calories/day
- Lose 2 lb/week: TDEE minus 1,000 calories/day
Minimum safe calorie intake
Never eat below 1,200 calories per day for women or 1,500 calories per day for men without medical supervision.
Worked example: 35-year-old woman, 160 lb, 5'5"
BMR = (10 × 72.6) + (6.25 × 165) − (5 × 35) − 161 = 1,421 calories
TDEE (moderately active): 1,421 × 1.55 = 2,202 calories
To lose 1 lb/week: 2,202 − 500 = 1,702 calories/day
The role of protein in fat loss
Target 0.7–1.0 grams of protein per pound of body weight daily. Protein helps preserve muscle mass during a deficit and increases satiety.