How the calorie target calculator works
The deficit/surplus magnitudes that work
Cutting: a 20% deficit loses ~0.5–1% of body weight weekly — the zone where fat goes and muscle stays. Gentle (10%) suits leaner individuals and maintenance-heavy lifestyles; aggressive (25%) suits higher body fats and short timelines. Bulking: 10% surplus adds ~1–2 lb/month, most of it muscle with proper training; bigger surpluses mostly buy fat you will pay to remove later.
Protein first, always
Protein is set by goal and body weight (0.8–1.0 g/lb) before any other macro because it does three jobs at once: preserves muscle in deficits, supports growth in surpluses, and is the most satiating macro in the plan. After protein, fat gets a floor (~0.3 g/lb) for hormonal function, and carbs take whatever remains — which is why "carbs are bad" arguments miss the actual accounting.
The weekly weigh-in contract
Targets are estimates wearing confidence. Weigh 3–4 mornings weekly, average them, judge the 4-week trend against the expected weekly change, and adjust by 100–200 kcal if reality diverges. This loop — not willpower — is what separates plans that work from plans that were calculated correctly and never corrected.