Sustainable Weight Loss

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.

Target Weight Loss Timeline Calculator

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