Tip: The Keto Diet Doesn't Like Muscle

New research reveals some disappointing news about ketogenic diets and muscle growth.

My aunt is mesmerized by a particular TV commercial. It's the one where they rub some "Miracle Cream" on the face of some guy who looks like Harry Dean Stanton's meth-freak brother and within minutes, the huge bags under his eyes – bags as big as the ones you chug wine out of at Burning Man – disappear. It's a miracle!

I haven't had the heart to tell her she could do the same thing with some Preparation H. The active ingredient simply constricts blood vessels, temporarily shrinking and tightening the tissues and muscles whether they're on your butt or on your face.

The thing is, she really wants it to work. Keto dieters have the same mindset, the same unrealistic expectations. They desperately want the diet to erase all fat while making them breathtakingly buff with mind-blowing endurance.

Sorry, keto fans. You can't have it all. You can be really lean and maybe even have increased endurance, but more muscle? Not gonna happen. At least that's what some Spanish researchers say after conducting a study on keto and resistance training.

The Spanish scientists recruited 24 weight-lifting hombres and split them into three groups. All followed an identical lifting plan for 8 weeks. One group – the keto group – went on a 3,000 calorie-plus hyper-caloric diet where they ingested 2 grams of protein per kilogram of bodyweight per day and less than 42 grams of carbs.

The second group also went on a 3,000 calorie-plus diet, but their protein and carb intake was "normal."

The third group ate their usual diets and served as the control group.

The keto group lost a lot of body fat, but they also lost a lot of visceral fat, which implies that the diet has positive cardio-protective benefits (as visceral fat has been implicated in cardiometabolic disease).

However, the keto group didn't gain any statistically significant amount of muscle, despite the hyper-caloric diet and high protein intake.

The non-keto, high-calorie diet group gained a tiny bit of fat (less than a pound), but along with that came a significant amount of lean body mass (over two kilograms).

The control group also gained nearly two kilograms of muscle, but they also porked out quite a bit, gaining roughly 1.5 kilograms of fat.

The researchers concluded the following:

"This research showed no significant changes nor effect size on lean body mass, despite hyper-energetic condition and high protein intake (2.0 g/kg/d) in resistance-trained men of the ketogenic diet group. Thus, we conclude that low-carbohydrate dietary approaches would not be an optimal strategy for building muscle mass in trained men under the training conditions of this study (mechanical tension-focused resistance training protocol during 8 weeks)."

Several previous studies on rats have also shown that the keto diet didn't elicit much muscle growth, even when paired with some sort of rodent resistance training, but researchers didn't think the results were extrapolable to humans.

Hence this study. And while the results of any one experiment can't be taken as gospel, this one seems to confirm what a lot of us in the biz believe: If you want to build muscle, the best approach is the time-honored and time-proven method of combining resistance training with high protein, adequate carbohydrates, and a caloric surplus.

  1. Vargas S et al. Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. J Int Soc Sports Nutr. 2018 Jul;15:31.