How Calorie Deficit Drives Weight Loss
Weight loss follows a simple energy balance principle: burn more calories than you consume. Approximately 7,700 kcal of deficit per kg of fat (3,500 kcal per lb) must be created to lose body fat. This calculator determines the daily deficit required to hit your weekly target.
The recommended safe range is 0.5–1.0 kg per week. Losing within 0.5–1% of body weight per week minimizes muscle catabolism while effectively targeting fat stores. Faster loss increases the risk of muscle loss, metabolic adaptation, fatigue, and nutritional deficiency.
Never drop below 1,500 kcal/day for men or 1,200 kcal/day for women without medical supervision. Pair your deficit with resistance training and adequate protein (1.6–2.2 g/kg/day) to preserve lean muscle mass throughout your diet.
Frequently Asked Questions
Severe calorie restriction causes muscle loss, metabolic slowdown, fatigue, poor concentration, and nutrient deficiencies. It is also the leading cause of rebound weight gain after dieting ends.
Yes — as your body weight decreases, your TDEE also decreases. Recalculate your deficit every 4–6 weeks to ensure your calorie target still creates the intended deficit at your new body weight.