Preserving Mass During A Cut

TL:DR - cutting catabolizes muscle, so do so when on cycle rather than off. 4-6% bf is obtainable.

Two seemingly unrelated studies below, when taken together, can help manage expectations as it relates to lower bf% limits, the sacrifice of muscle to achieve increasingly lower body fat, but that hypertrophy can still be possible in some situations. Since many of us are currently bulking, this is a reminder that when time comes to cut, do so with the goal of preserving as much muscle while losing as much fat as possible.

Lower Limit of BF% in Healthy (and presumably natty) Men

55 ‘normal’ young men attended an 8 week Army combat leadership training course involving strenuous exercise and a caloric deficit of 1200 calories per day. At the start of the course, body fat percentage (assessed by DEXA) was 14.3%, while at the end it averaged 5.8%. Those between 4-6% body fat toward the end of the training saw only marginal decreases in body fat % while sacrificing increasingly large amounts of muscle.

This was due to once fat levels reaching a certain level, protein catabolism increases. As you would expect, muscle size also significantly decreased. Biceps had a baseline of 33.7 and by week 8 had decreased to 30.5 inches. Full table of all changes here.

What’s also interesting was the lack of outliers, with a pretty normal standard distribution at baseline, but by week 8 the majority of folks were between that 4-6% range, and everyone was 12% or less.

Findings have been replicated at least once before, in 1950 and with similar outcomes. While Study 1 occurred in 1992 and aas were definitely widespread by this time, the fact that the outcomes were similar to a much earlier study where PEDs were not as common leads me to believe that participants were natty. Besides, these were US Army Rangers all likely in excellent condition even before the study.

Hypertrophy While Losing Weight

So I’m gonna lose muscle while cutting, right? Probably, but not in all situations.

14 obeast women received about 800 calories a day for 3 months. Half engaged in weight training, while the other half remained sedentary. After 90 days, all subjects had lost weight with most (76%) being lost from fat, while the balance lost from fat free mass. The type of weight loss was not different between the two groups, however biopsy indicated that the weight trained subjects had an increase in slow and fast twitch muscle fibers indicating hypertrophy.

A second related subject focussed on 40 obeasts who were split into 4 groups. The group that had a caloric deficit combined with weight training had comparable weight loss to the group that had a caloric deficit but no exercise, but increased LBM slightly.

It’s hard to make too much of the latter two studies, since we’ve known forever that muscle growth and fat loss (i.e. recomp) is possible at a caloric deficit in untrained subjects. However, the finding can be presumably extended to untrained body parts - for example, in a highly trained individual who does not typically directly train triceps or calves, hypertrophy during a cut would be possible in those muscle groups.

Maintaining Muscle & Use of PEDs

We’ve covered this somewhat earlier in Post Cycle Strength Preservation and much of this applies to cutting too. In summary (though I recommend reading the entire thing) this is:

Conclusion

Study 1 reminds us of the catabolism that occurs when losing weight, and is one of the reasons why cutting off cycle is a bad idea. This is increasingly accurate the lower one's body fat is, as muscle loss in relation to fat loss increases. However, study 2 also shows us that during a cut an increase in volume for untrained body parts can continue to trigger hypertrophy. This is likely true for even maintaining muscle mass in key areas. I’m a fan of MK677 off-cycle and so long as you can manage the hunger cravings it can be well utilized in a cut too.