· Updated · By Kaunto
The Best Macro Split for Cutting (And Why the Split Matters Less Than You Think)
Set protein high, fat to a floor, and carbs with whatever's left. Here's how to calculate a cutting split, with worked numbers.
For fat loss, set protein at 2.0–2.4 g per kg of bodyweight, fat at no less than about 20% of calories, and fill the remaining calories with carbohydrate. In percentage terms that usually lands somewhere around 30–35% protein, 20–30% fat, 35–45% carbs — but percentages are the output, not the input. Two people at the same “40/30/30” can have wildly different protein in grams, and grams are what your body responds to.
Set the deficit first
The split does nothing without an energy deficit. Sequence matters:
- Estimate maintenance calories with the macro calculator or the method in how many calories should I eat a day. Or take the average of two weeks of honest logging at stable weight, which is more accurate than any formula.
- Subtract 15–25%. That’s a rate of roughly 0.5–1.0% of bodyweight lost per week. In a controlled trial of athletes, the faster rate cost lean mass without adding fat loss.
- Then split the remaining calories using the priority order below.
The priority order
Protein first — 2.0–2.4 g/kg. In a deficit, the body will take amino acids from somewhere. High protein plus resistance training is what makes that somewhere not your muscle. Higher-protein meals also modestly increase fullness, which helps the deficit. See how much protein per day for where those numbers come from.
Fat second — a floor, not a target: about 20% of calories. Reference intakes put fat at 20–35% of energy, and contest-preparation reviews go as low as 15%. Set the floor and don’t go under it. In a deficit there’s little reason to go far above it either: every gram of fat costs 9 kcal that carbohydrate could fill.
Carbs last — whatever calories remain. Carbohydrate is the training fuel. Whatever is left after protein and fat should go here, because it’s what keeps your lifts from collapsing while you’re eating less. If your remaining carb number comes out very low, your deficit is too aggressive — raise calories rather than cutting fat below the floor.
Worked example
An 80 kg person, maintenance ≈ 2,600 kcal, cutting at a 20% deficit:
| Step | Calculation | Result |
|---|---|---|
| Target calories | 2,600 × 0.80 | 2,080 kcal |
| Protein | 80 kg × 2.2 g | 176 g → 704 kcal |
| Fat | 2,080 × 25% ÷ 9 | 58 g → 522 kcal |
| Remaining for carbs | 2,080 − 704 − 522 = 854 kcal | 214 g |
| Resulting split | — | 34% P / 25% F / 41% C |
Note that this “best” cutting split is 41% carbohydrate — nowhere near the low-carb prescriptions that dominate cutting advice. That falls out of the arithmetic, not from a preference.
Common splits compared
| Split (P/C/F) | Who it suits | Trade-off |
|---|---|---|
| 40/40/20 | Lifters cutting with high training volume | Fat sits at the bottom of the reference range |
| 35/35/30 | Most people, most of the time | The reasonable default |
| 40/20/40 (low-carb) | People who prefer it, or who find carbs trigger overeating | Training performance often drops; no metabolic advantage at matched protein and calories |
| 30/50/20 | Endurance athletes cutting | Protein may be too low to fully protect lean mass |
Direct comparisons of low-carb against higher-carb diets, when calories and protein are matched, consistently show no meaningful difference in fat loss. The split you’ll actually adhere to beats the split that’s theoretically 2% better.
What to change when the scale stalls
A stall of under two weeks is usually water, not fat — especially around a change in training, sodium, or the menstrual cycle. If it persists past two to three weeks:
- Check your logging honestly. Under-reporting is common and large: in one study, people who said they could not lose weight were eating 47% more than they recorded — untracked oils, drinks, and bites. Weigh food for a week before concluding your metabolism is the problem.
- Reduce calories by 5–10%, taken from carbs and fat, never protein.
- Add activity instead of cutting further if you’re already at a steep deficit.
- Consider a maintenance break. In one trial, alternating two-week blocks of dieting with two weeks at maintenance gave more fat loss than continuous dieting, though over a longer total period.
Sources
- Helms ER, Aragon AA, Fitschen PJ. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition 11:20. doi:10.1186/1550-2783-11-20
- Garthe I, Raastad T, Refsnes PE, et al. (2011). Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism 21(2):97–104. doi:10.1123/ijsnem.21.2.97
- Longland TM, Oikawa SY, Mitchell CJ, et al. (2016). Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. American Journal of Clinical Nutrition 103(3):738–746. doi:10.3945/ajcn.115.119339
- EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). Scientific Opinion on Dietary Reference Values for fats. EFSA Journal 8(3):1461. doi:10.2903/j.efsa.2010.1461
- Hall KD, Guo J. (2017). Obesity energetics: body weight regulation and the effects of diet composition. Gastroenterology 152(7):1718–1727. doi:10.1053/j.gastro.2017.01.052
- Lichtman SW, Pisarska K, Berman ER, et al. (1992). Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine 327(27):1893–1898. doi:10.1056/NEJM199212313272701
- Byrne NM, Sainsbury A, King NA, et al. (2018). Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. International Journal of Obesity 42(2):129–138. doi:10.1038/ijo.2017.206
Frequently asked questions
What is the best macro split for fat loss? Protein 2.0–2.4 g/kg, fat at no less than about 20% of calories, carbs with the remaining calories, inside a 15–25% deficit. Expressed as percentages that’s typically around 34/25/41 P/F/C, as in the worked example, but the grams are what to set.
Should I cut carbs or fat? Fat, down to the floor of about 20% of calories — then carbs. Cutting carbs first tends to hurt training performance, which is what preserves muscle in the first place.
How fast should I lose weight when cutting? 0.5–1.0% of bodyweight per week. In a trial of athletes, losing faster cost lean mass without adding fat loss.
Do I need to hit my macros exactly? No. Within about 5–10 g of each target is a normal successful day, and the weekly average matters more than any single day.
Does meal timing matter for cutting? Very little compared with the daily totals. Spreading protein across 3–5 meals is a mild optimisation; when you eat your carbs is largely preference and training schedule.
Not sure whether to track macros at all? Start with macros vs calories.