The short answer: cut 15–25% below your TDEE. For most people, that's 300–500 kcal per day. This produces 0.5–1% of bodyweight lost per week, protects muscle, and stays sustainable long enough to actually finish the cut.
Bigger deficits lose weight faster, lose muscle faster, and rebound faster. Smaller deficits work but take longer. The sweet spot — the one that gets results without trashing your training, sleep, or sanity — sits in that 15–25% window.
The formula
Target calories = TDEE × (1 − deficit %)
Example — a 2,800 kcal TDEE:
- 15% deficit (conservative) → 2,380 kcal/day → ~0.5% bodyweight/week
- 20% deficit (standard) → 2,240 kcal/day → ~0.7% bodyweight/week
- 25% deficit (aggressive) → 2,100 kcal/day → ~1% bodyweight/week
Weekly loss in kg = (daily deficit × 7) ÷ 7,700 kcal/kg
Don't know your TDEE? Start with the TDEE calculator.
Which deficit to pick
15% — the conservative cut
Pick this if you're:
- Already lean (under 15% body fat for men, under 22% for women)
- Doing a long cut (12+ weeks)
- Training hard and want to protect every rep
- Prone to binging or diet burnout
Progress is slow (0.3–0.5 kg/week for most people) but the cut is sustainable and muscle-protective.
20% — the standard cut
The default for most lifters. Pick this if you're:
- In the 15–25% body fat range (men) or 22–32% (women)
- Looking at a 6–10 week cut
- Training consistently
Weekly loss typically 0.5–0.8 kg. This is what the cutting macros calculator uses by default.
25% — the aggressive cut
Pick this if you're:
- Above 25% body fat (men) or 32% (women) — larger deficits are safer when you have more fat to lose
- Short on time (4–8 week cut window)
- Willing to trade some training performance for speed
Past 25%, muscle-loss risk rises sharply. Past 30%, research shows roughly half of lost weight comes from lean mass in trained lifters.
Why deficits above 25% backfire
Large deficits create four problems that compound:
- Muscle loss accelerates. Protein demand rises in a deficit; large deficits mean protein alone can't protect muscle — training stimulus and available calories both matter.
- Adaptive thermogenesis kicks harder. Your body compensates by lowering NEAT (unconscious movement), lowering resting metabolism, and dialling back hormones. A 1,000 kcal deficit often becomes a 500–700 kcal real deficit within weeks.
- Training performance drops. Less fuel means worse lifts, which means less muscle-protective stimulus.
- Adherence collapses. Hunger exceeds what diet discipline can offset. Most "I can't lose weight" stories are extreme deficits followed by extreme overeating.
The "crash" pattern is predictable: fast loss for 2–3 weeks, stall, fatigue, binge, rebound. A moderate deficit that you actually finish beats an aggressive one that you don't.
Protein protects muscle during the deficit
The deficit size picks how fast you lose weight. Protein picks what you lose — fat or muscle.
- Minimum: 1.6 g/kg of bodyweight
- Recommended: 2.2–2.6 g/kg during a cut
- Lean and aggressive cut: up to 3.1 g/kg
A 2014 study (Longland et al.) compared 1.2 vs 2.4 g/kg protein during a 40% deficit — the high-protein group gained muscle despite the large deficit; the low-protein group lost 1.5 kg of lean mass. Protein is that important.
Every gram of protein below target is a gram of muscle you're trading away.
When to recalculate
Recompute your target calories every 4–5 kg of weight lost. Reasons:
- Your new (lower) bodyweight has a lower BMR
- Adaptive thermogenesis has reduced your true TDEE below the formula's estimate
- The old deficit may no longer produce any loss
Rule of thumb: weight loss stall for 10+ days while adherence is solid → drop 100–150 kcal and retest for two weeks.
How to track progress
- Weigh daily at the same time (morning, after bathroom, pre-food). Don't interpret single days.
- Compare 7-day averages week-on-week. A single weekly weigh-in hides too much noise.
- Track waist measurement weekly. On cuts, waist often drops before the scale does.
- Recheck body fat every 4 weeks using the body fat calculator.
A cut is working if you're losing 0.5–1% of bodyweight per week averaged over 2+ weeks. More = too aggressive. Less = too small, or adherence issue.
When to stop
End the cut when:
- You've hit your target body fat or bodyweight
- You've been cutting 12+ weeks without a diet break (take 2 weeks at maintenance before resuming)
- Performance or adherence is collapsing
Don't cut year-round. Most trainees lose 5–10 kg per cycle, maintain for 2–4 weeks, then either bulk or cut again.
Bottom line
- 15% deficit (conservative) — already lean, long cut, prioritising muscle
- 20% deficit (standard) — most people, most cuts
- 25% deficit (aggressive) — higher body fat, short timeline
- Never below 1.6 g/kg protein; aim 2.2–2.6 g/kg on a cut
- Recalculate every 4–5 kg lost
Run the numbers for your bodyweight and TDEE in the cutting macros calculator.
Related
- TDEE Calculator — find your maintenance calories first
- Cutting Macros Calculator — set a deficit and get exact macro targets
- Macro Calculator — maintenance macros between cuts