Strip away every diet trend and one equation remains: consistent energy deficit causes weight loss. The useful part is putting numbers on it — because vague "eating less" fails where specific targets succeed.
Find Your Maintenance First
Your TDEE (total daily energy expenditure) = BMR (what your body burns at rest — roughly 22 kcal per kg of bodyweight, adjusted for age and sex) × an activity multiplier (1.2 sedentary to 1.7 very active). An 80kg moderately active man lands around 2,600–2,800 kcal/day.
The 500-Calorie Rule
A ~500 kcal daily deficit produces roughly 0.5kg of fat loss per week (a kg of body fat stores ~7,700 kcal). It is aggressive enough to see progress, mild enough to sustain and keep training quality. Deficits beyond 750–1,000 kcal accelerate muscle loss and rebound risk.
Why the Scales Lie
Daily weight swings 1–2kg on water, salt, carbs and timing — none of it fat. Weigh daily, average weekly, judge the trend across 3–4 weeks. A salty restaurant meal can mask a genuine fat-loss week entirely.
Protect Muscle While Losing
Two rules: resistance training 2–3× weekly, and protein at ~1.6–2.2g per kg of bodyweight. Weight loss without them is part muscle — which lowers your TDEE and sets up the regain cycle.