Weight Loss Calculator

Calculate TDEE (your maintenance calories) and subtract 300 to 500 for steady fat loss of 0.25 to 0.5 kg per week. Example: TDEE 2200 kcal, eat 1700–1900. Don't drop below your BMR (typically 1300–1500 for women, 1600–1800 for men). Aggressive deficits (1000+ below TDEE) cause muscle loss, fatigue, and rebound. Make protein the priority — 1.6 to 2.2 g/kg body weight protects muscle during the deficit. Track for 2 weeks; if weight isn't moving, reduce by another 100–200 kcal. Slow, sustainable loss outperforms fast loss every time.

A safe deficit is 300 to 500 kcal/day for most adults — that's 0.25 to 0.5 kg per week. Larger deficits work short-term but accelerate muscle loss, hormonal disruption, and rebound eating. Severely overweight individuals can sustain deficits up to 750 kcal/day under medical supervision. For everyone else, 500 is the practical ceiling. Below 1200 kcal/day for women or 1500 for men, micronutrient deficiencies become common. Combine the deficit with strength training, adequate protein, and sleep for best results. Slow loss is real loss; rapid loss is mostly water and muscle that returns quickly.

About 10 to 20 weeks at a sustainable rate of 0.5 kg per week. Faster initial loss (the first 1–2 weeks) is partly water as glycogen depletes — that's normal and doesn't mean fat is leaving fast. After that, expect 0.5 kg per week with a 500 kcal/day deficit, less if you're already lean. Plateaus are common around weeks 6–8 — adjust calories down or activity up. The math: 1 kg fat = roughly 7700 kcal, so 10 lbs (4.5 kg) needs about 35,000 kcal deficit, or 70 days at 500/day. Reality follows roughly, with normal week-to-week variation.

Several common reasons. Body adapts to a deficit by lowering metabolism slightly (metabolic adaptation), so the same calorie target produces less loss after weeks. Smaller body burns fewer calories at rest, so TDEE drops as you lose weight. Activity NEAT (non-exercise activity) often drops unconsciously when in a deficit — you fidget less, walk less. Tracking accuracy slips after the initial enthusiasm. Water retention from new training routines, hormonal changes, or stress can hide fat loss for weeks. Recheck your TDEE, retighten tracking, and add a diet break (eat at maintenance for a week) to reset.

Total weight to lose ÷ weekly loss rate = number of weeks. Example: 10 kg to lose at 0.5 kg/week = 20 weeks. Add 25% buffer for plateaus, slowdowns, and life events — realistic timeline is 25 weeks (about 6 months). Faster targets are common but rarely sustainable. The total calorie deficit needed: total weight to lose in kg × 7700 kcal/kg = total deficit. For 10 kg, that's 77,000 kcal — at 500/day that's 154 days. The math gives a planning estimate, not a precision date. Track progress every 4 weeks and adjust the timeline based on actual results.

Use TDEE as the reference and subtract a deficit. BMR is too low — eating below BMR causes metabolic slowdown, fatigue, and muscle loss. TDEE represents your actual daily calorie needs including activity. Deficit = TDEE × 0.85 (modest) to TDEE × 0.75 (aggressive but still sustainable). Example: TDEE 2400. Modest deficit: 2040. Aggressive: 1800. Stay above BMR (typically 1500). Recalculate TDEE every 5–10 kg of weight loss because as weight drops, so does TDEE. Calorie targets aren't static — they need updating throughout the journey. Aim for the smallest deficit that still produces consistent loss.