A cut is supposed to take fat off and leave the muscle you built. Done badly, it takes both. Three things decide which way it goes.
1. Lose it slowly
The faster you drop weight, the more of it tends to be muscle. A widely used set of recommendations for natural lifters by Helms, Aragon and Fitschen (2014) suggests losing 0.5 to 1% of your body weight a week.
| Body weight | 0.5% a week | 1% a week |
|---|---|---|
| 70 kg | 0.35 kg | 0.7 kg |
| 80 kg | 0.4 kg | 0.8 kg |
| 90 kg | 0.45 kg | 0.9 kg |
Leaner people should sit nearer the slower end: they have less fat to give up and more muscle at risk.
In practice that usually means eating 10 to 25% below what you burn. Liftprep's "steady" pace sets a 20% deficit and its "gentle" pace 12%, and it will not plan below a safe minimum (1,500 kcal for men and 1,200 for women) however aggressive the goal.
2. Keep protein high
In a deficit your body is more willing to break down muscle for fuel, and protein is what protects it. The same 2014 recommendations put protein at 2.3 to 3.1 g per kg of lean body mass while cutting. For most people that works out at roughly 2 to 2.5 g per kg of total body weight.
Liftprep sets 2.2 g per kg when you are losing fat. There is more on protein targets in how much protein you need to build muscle.
3. Keep lifting heavy
Training is the signal that tells your body the muscle is still needed. Keep the heavy compound lifts in, at roughly the same weights, even if you cut back on total volume when energy is low. A cut is not the time to switch to light weights and high reps.
Judge it by the weekly average, not the morning
Body weight moves by a kilo or more from day to day on water, salt and food in your gut. One morning tells you very little. Weigh in a few mornings a week and compare weekly averages.
If the weekly average has not moved for two weeks, the deficit is too small. If it is dropping faster than 1% a week, it is probably too big. Liftprep does this check for you: log your weight a few times a week and your targets move if you are off pace for two weeks running.
The short version
- Lose 0.5 to 1% of your body weight a week.
- Eat 10 to 25% under maintenance, never below a safe floor.
- Keep protein around 2.2 g per kg.
- Keep lifting heavy.
- Judge progress by weekly averages.
Find your numbers with the free calculator.
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.
- Mifflin MD et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51: 241–247.