WEIGHT LOSS
CALCULATOR
How long will it take to reach your goal weight? Get a realistic, science-based timeline.
What This Calculator Does
The Weight Loss Calculator projects your fat loss timeline based on your current weight, goal weight, and chosen calorie deficit. It uses the validated 7,700 kcal/kg deficit model to give realistic weekly targets and a completion date.
The Formula Explained
1kg of fat ≈ 7,700 kcal. 500 kcal daily deficit → 3,500 kcal/week → 0.45kg/week. Example: lose 10kg at 500 kcal/day deficit → 10 ÷ 0.45 = ~22 weeks. For a 750 kcal deficit: same 10kg in ~15 weeks but higher muscle loss risk.
What Your Result Means
Safe fat loss is 0.5–1% of body weight per week. Faster loss increases muscle breakdown risk — studies show up to 40% of rapid weight loss can be lean mass. For best body composition: combine a 500 kcal deficit with adequate protein (1.8–2.4g/kg) and resistance training.
Calorie Calculator to set your exact daily target · TDEE Calculator to find your maintenance calories
The Science of Fat Loss Timelines
One pound (0.45kg) of fat contains approximately 3,500 calories. Therefore, a daily deficit of 500 calories produces roughly 0.45kg of fat loss per week — a well-validated rule of thumb, though individual metabolic adaptation means real results vary. Safe, sustainable fat loss rates are generally 0.5–1% of body weight per week, which minimizes muscle loss and metabolic adaptation while allowing consistent progress.
Why Slower Is Often Better
Very aggressive deficits (above 750–1,000 cal/day) accelerate lean mass loss, reduce metabolic rate through adaptive thermogenesis, increase cortisol and hunger hormones, and are more difficult to sustain long-term. Research consistently shows that slower weight loss strategies produce better body composition outcomes and better weight maintenance.