The Calorie Deficit Math
One pound of fat contains approximately 3,500 calories. To lose one pound per week, you need a deficit of 500 calories per day. To lose half a pound per week — a gentler, more sustainable pace — you need a 250-calorie daily deficit. Most experts recommend staying within a 300–500 calorie daily deficit for steady, muscle-preserving fat loss.
Approximate TDEE by Activity Level for Women
- Sedentary (desk job, minimal movement): Multiply BMR × 1.2
- Lightly active (light exercise 1–3 days/week): Multiply BMR × 1.375
- Moderately active (exercise 3–5 days/week): Multiply BMR × 1.55
- Very active (hard exercise 6–7 days/week): Multiply BMR × 1.725
A simple BMR starting estimate for women: 655 + (4.35 × weight in lbs) + (4.7 × height in inches) − (4.7 × age). Subtract 300–500 from your TDEE for your daily weight-loss calorie target.
Minimum Calories and Protein Targets
Never eat below 1,200 calories per day without medical supervision. Going too low causes muscle loss, nutrient deficiencies, hormonal disruption, and metabolic slowdown. Most women lose weight effectively at 1,400–1,800 calories depending on size and activity level.
Protein is essential during weight loss. Target at least 0.7g per pound of body weight (or 1.0g if you strength train) to preserve muscle while in a calorie deficit. For a 150 lb woman, that means 105–150g of protein per day.
