A diet plus a lot of sets sounds like a sure way to lose muscle. The logic is tidy: in a deficit you recover worse, so why not cut the volume? The data do not sit neatly with that.
Short answer: Do not cut your sets just out of habit. In a fresh study, advanced lifters in a 40% deficit kept their lean mass over four weeks with 12 sets a week per muscle and with 30. More sets added more strength. It is still a preprint, waiting on review, so treat it as a signal, not a finished rule.
What the study actually did
A paper in the European Journal of Clinical Nutrition, still a preprint and still under review, pushes on the old picture.
They took advanced lifters, put them in a 40% deficit with plenty of protein, and followed them for four weeks. Half trained 12 sets a week per muscle, a middle volume. The other half trained 30 sets, which is a real amount of work.
Then came the DXA scans. Between the groups there was no statistically significant difference in body composition. Both groups lost a decent amount of fat and kept their lean mass.
Where they split was strength. The 30-set group added 15 to 27% on the strength tests. The 12-set group added 7 to 14%.
The open question is whether that is real muscle growth or the body simply learning the movement better (a neural adaptation). Four weeks, measured by DXA, cannot separate the two. How to keep muscle while the calories are down is the wider picture in build muscle in a calorie deficit.
What to take into the gym
Do not cut volume on a diet just because that is the habit. Muscle tolerates more than most people think. A sensible plan decides it, not the fear of losing muscle.
And still: this is a preprint waiting on review. I take it as an interesting signal, not a closed case. If you only have one short session in the week, the minimum that still works is in strength training: one hour a week. The protein that sits under either volume is in how much protein.
The pace of the deficit matters too. A 40% cut is aggressive, and this study ran it for four weeks in people who already lift. For a longer fat-loss block, the pace that most people can keep is in how fast should you lose weight.
Frequently asked questions
How did the training-volume study run?
Advanced lifters ate in a 40% deficit, with plenty of protein, for four weeks. Half did 12 sets a week per muscle. Half did 30.
Was there a difference in body composition between 12 and 30 sets?
On DXA, no statistically significant difference. Both groups lost a decent amount of fat and kept their lean mass.
How much more strength did 30 sets add?
The 30-set group gained 15 to 27% on the strength tests. The 12-set group gained 7 to 14%. Four weeks and a DXA scan cannot tell muscle growth from a neural adaptation.
What should you do with this?
Do not cut sets on a diet just out of habit. Muscle can take more work than you think. A sensible plan decides it. This is a preprint under review, so it is a signal, not a final rule.
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Apply for coaching Get the free Fat Loss KitSources, so you can check:
1) Nait-Yahia S. The effects of high resistance training volume during caloric restriction. European Journal of Clinical Nutrition. Preprint, under review (2026). No DOI printed in the source article.
Martin Barna
Online nutrition and fitness coach. Since 2013 I have helped 600+ people lose fat and keep the result. Science, not crash diets.
Apply for coachingThis article is for information only. It is not medical advice. If you have a health condition, talk to your doctor.