Target Weight Loss Timeline Calculator
Set a target weight and see exactly how long it takes at different rates of loss. Based on realistic, sustainable fat loss rates rather than crash diet timescales.
The 7,700 kcal Rule
1 kg of body fat contains approximately 7,700 kcal. To lose 0.5 kg/week requires a weekly deficit of 3,850 kcal — or 550 kcal/day below TDEE. This can come from reduced eating, increased activity, or both.
Why Slower Is Often Better
Aggressive deficits (750+ kcal/day) increase muscle loss, fatigue, and hormonal disruption. They also have poor adherence — most people abandon extreme diets within weeks. A 500 kcal/day deficit is uncomfortable but sustainable for most people and preserves more lean muscle.
Non-Linear Progress
Weight loss is not linear — expect water weight fluctuations of ±1–2kg daily. Track trends over weeks, not daily readings. A 4-week rolling average is more meaningful than yesterday's weight. Progress stalls happen and are normal — recalculate TDEE every 5kg lost.
When to Seek Medical Advice
Calculator results are estimates based on population averages and statistical formulas — they are not medical diagnoses. Consult your GP if calculator results suggest a health concern, if you have symptoms requiring attention, or if you are managing a chronic condition where precise monitoring is important. Regular health checks (annual GP review, NHS Health Check for those aged 40-74) provide professional assessment using validated clinical tools. Use health calculators to inform conversations
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