Cutting: losing fat without wrecking your performance

Cutting means losing fat mass while holding on to as much muscle as possible. It runs on a moderate calorie deficit, enough protein and heavy strength training. In research on elite athletes, a pace of roughly 0.7 percent of bodyweight per week worked out better than twice that rate.

That figure is the one thing most people miss. They are not choosing between "cutting" and "not cutting", they are accidentally choosing the pace that costs them strength.

What exactly is cutting?

Cutting is a period in which you deliberately take in less energy than you use, in order to lose fat. The difference from ordinary dieting is the intent: you are trying to hold on to your fat-free mass and your strength as much as possible. That makes the approach different from a diet.

The name suggests the training does the work. In practice the nutrition does most of the work, and the training protects what you have.

How much energy you actually use is covered in calculating your calorie needs. Without that starting point, you are guessing.

How fast can you cut without losing muscle?

Slower than most people want. One study on elite athletes compared two rates: roughly 0.7 percent and roughly 1.4 percent of bodyweight per week. The slower group retained more fat-free mass and showed better strength results (Garthe et al., 2011).

For someone at 85 kilos, that slower pace comes to roughly 600 grams a week. It feels slow. It is also why people who stick with it look better at the end than people who forced it into six weeks.

A meta-analysis also showed that an energy deficit mainly holds back gains in lean mass, while strength gains hold up better (Murphy and Koehler, 2022). So during a cut you usually do not get weaker straight away, you just build very little.

How much protein do you need during a cut?

More than outside a cut, because protein helps protect your fat-free mass in a deficit. A review of contest preparation in natural bodybuilders describes intakes around 2.3 to 3.1 grams per kilo of fat-free mass for the hardest phases (Helms et al., 2014). That is a sport context, not general advice.

The Dutch Voedingscentrum uses far lower guidelines for the general population, and that gap makes sense: a cutting lifter and an average adult are not doing the same thing.

The practical version is in how much protein per day. For spreading it across your day, see calculating your macros.

What happens to your hormones during a long cut?

A prolonged and large deficit can shift the hormonal picture. The literature on contest preparation describes falls in testosterone and thyroid hormone, alongside more hunger and less appetite for training. Those changes generally recover once energy intake goes back up.

This is the part the fitness industry would rather not discuss, because it sells badly next to a before-and-after.

What that means for your blood values depends heavily on how deep and how long you go. An eight-week cut on a moderate deficit is a different thing from six months on half rations.

Which blood values can change if you cut too hard?

Some values respond to a long, heavy deficit. Think of testosterone, free T3, ferritin and sometimes CK after a hard session. None of those values proves anything on its own, but alongside how you feel, how you sleep and how you lift, they form a usable picture.

If you want to look into this, total testosterone and ferritin are the most requested. Some athletes track these during a long block through a hormone panel or a wider 360 Health panel.

The explanation per value is in spotting overtraining in your blood values and in iron deficiency in athletes.

When should you pause a cut?

When the cost starts outweighing the return. Signals that often come with that: your strength drops several weeks running, you sleep worse, you are cold all the time, and your recovery between sessions lags. A planned period at maintenance can then deliver more than pushing through.

I would rather pause a week early than a month late. A cut that blows up costs you two blocks instead of one.

Take a lifter in week ten, three kilos further down than planned, watching his bench drop by 7.5 kilos. That is not a matter of wanting it more. That is a deficit that stayed too large for too long.

When you build back up afterwards, do it in a controlled way. How that works is in lean bulk. What the fat you are losing actually is can be found in visceral fat and reducing visceral fat.

From this week, put three things in your log: your weight on fixed days, your top sets, and how you slept. Those three together will tell you something is going wrong long before the mirror does.

References

• Garthe I et al. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab, 2011. PMID 21558571
• Murphy C, Koehler K. Energy deficiency impairs resistance training gains in lean mass but not strength: a meta-analysis and meta-regression. Scand J Med Sci Sports, 2022. PMID 34623696
• Helms ER et al. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr, 2014. PMID 24864135
• Voedingscentrum, guidelines on protein intake for the general population.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.