TDEE (Total Daily Energy Expenditure) is the total calories your body burns in 24 hours including all activity.

Formula: TDEE = BMR × Activity Multiplier.

BMR (Basal Metabolic Rate) is calories burned at rest, calculated using Mifflin-St Jeor equation: Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5.

Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161.

Activity multipliers: Sedentary (desk job, no exercise) = 1.2, Light activity (1-2 days/week exercise) = 1.375, Moderate (3-5 days/week) = 1.55, Very active (6-7 days/week) = 1.725, Athlete (2x daily training) = 1.9.

Example: 30-year-old woman, 70kg, 165cm, moderate activity: BMR = 1,432 cal, TDEE = 1,432 × 1.55 = 2,220 calories/day.

Weight loss: Eat 15-25% below TDEE (300-500 cal deficit).

TDEE 2,000 cal → eat 1,500-1,700 cal for 0.5-1 lb loss/week.

Muscle gain: Eat 10-20% above TDEE (200-400 cal surplus).

TDEE 2,500 cal → eat 2,700-2,900 cal for 0.25-0.5 lb gain/week.

Maintenance: Eat at TDEE exactly.

Track weight weekly and adjust calories if not progressing—metabolism adapts over time.

Prioritize protein: 0.8-1g per lb bodyweight for muscle preservation during cuts or growth during bulks.

Recalculate TDEE every 10-15 lbs weight change as BMR decreases with weight loss or increases with muscle gain.