Can You Build Muscle on Keto? Meta-Analysis Reveals Surprising Results
Finally, some sensible recommendations around keto and muscle building.
This systematic review and meta-analysis examined whether a ketogenic diet, when combined with resistance training, can increase muscle mass in people who already train regularly.
Why does this matter? It’s a question that surfaces often, because many lifters, for a variety of reasons, want to build muscle while drastically cutting carbs.
PMID: 36231929
Key Points
Researchers conducted a systematic review and meta-analysis to determine if ketogenic diets without energy restriction could increase fat-free mass in resistance-trained individuals. The study analysed five randomised controlled trials involving 111 total participants (87 men and 24 women), comparing ketogenic diet groups against control diet groups, all while participants engaged in resistance training.
Aim
The aim was to verify whether a ketogenic diet without programmed energy restriction generates increases in fat-free mass in resistance-trained participants who are also performing strength training.
Methods
The researchers searched three major databases (PubMed, Scopus, and Web of Science) through March 2022. Studies had to meet specific criteria: randomised trials lasting at least eight weeks, ketogenic diet implementation in resistance-trained participants, body composition measurement via DXA (dual-energy X-ray absorptiometry) or bioimpedance, and no use of supplements. The ketogenic diets in these studies involved carbohydrate intake below 50 grams per day or less than 10% of total calories, with substantial increases in fat intake. Five studies ultimately met all inclusion criteria, examining 48 participants on ketogenic diets and 53 in control groups.
Results
The meta-analysis revealed no significant differences in fat-free mass between the ketogenic diet and control diet groups. For total body mass, five studies provided data showing a mean difference of 0.31 kilograms in favour of the control group, though this was not statistically significant. For fat-free mass specifically, four studies contributed data showing a mean difference of -0.57 kilograms in favour of the ketogenic diet group, but again, this difference was not statistically significant. The heterogeneity across studies was 0% for all analyses, and no publication bias was detected.
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Discussion Points
The authors identified several critical limitations affecting the results. A major issue was that eight of the studies analysed used ad libitum (eat as desired) approaches rather than controlled calorie prescriptions, making it difficult to ensure participants consumed adequate total energy. Since an energy surplus is considered the main factor for increasing muscle mass, the satiety effect of ketogenic diets may have prevented participants from consuming enough calories to support muscle growth. Research has shown that ad libitum ketogenic diets result in lower total energy consumption, which could impair muscle gains regardless of the diet’s macronutrient composition.
