Weight Loss Timeline Calculator

At 500 kcal/day deficit: ~5.5 months (22 weeks). At 300 kcal: ~9 months. At 700 kcal: ~4 months. Week 1–2 often shows additional 1–4 kg water loss as glycogen depletes — this inflates early progress. Real fat loss follows the 7700 kcal/kg rule. In practice, add 10–20% to estimates for metabolic adaptation (TDEE decreases as weight drops, shrinking your real deficit over time).

Sustainable range: 300–500 kcal/day. 500 kcal → ~0.45 kg/week fat loss with manageable hunger. Aggressive: 700–1000 kcal — acceptable for shorter periods (<12 weeks) or for individuals with high starting BMI. Minimum: 200 kcal/day shows measurable fat loss. Above 1000 kcal/day deficit risks muscle loss, hormonal disruption (cortisol spike, thyroid slowdown), vitamin deficiencies, and excessive fatigue — counterproductive for long-term results.

Common causes: (1) Metabolic adaptation — TDEE drops 100–400 kcal during sustained deficits. (2) Water retention — stress, high sodium, hormonal cycles, and DOMS (muscle repair) all cause temporary water weight masking fat loss. (3) Tracking errors — studies show self-reported intake is underestimated by 20–40% on average. (4) Muscle gain — if training, simultaneous muscle gain can equal fat loss on the scale. Solution: measure body fat % and tape measurements, not just weight.

Gold standard: 0.5–1.0% of bodyweight per week. 90 kg person → 0.45–0.9 kg/week. 70 kg person → 0.35–0.7 kg/week. Slower (0.25–0.5 kg/week) maximises muscle retention — best for lean individuals. Faster (1–2 kg/week) acceptable for individuals with significant obesity (BMI >35). The most critical factor for body composition: keep strength training throughout the deficit to preserve lean mass.