If I may renew a topic found in my previous post — One Reason You Probably Shouldn’t Do Keto Diet — I have a bit more to say about the keto diet. This time, it’s about its effect on muscle growth. Does the keto diet compromise muscle gain?

Those among you who have a love affair with keto may wish to take a moment here to tighten up those sphincter muscles because the body of the evidence looks rough for the keto diet.

A 2018 study by Vargas et al…

Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial

…evaluated the efficacy of an 8-week keto diet during calorie surplus and resistance training protocol on body composition in trained men.

The subjects with more than 2 years of resistance training experience were randomly assigned to the keto diet group, non-keto diet group, and control group. Here is the macro breakdown for the keto and non-keto diet groups:

Macronutrient distribution for NKD group was about 55% CHO; 20% PRO and 25% FAT. / Macronutrient distribution for KD group was about <10% CHO; 20% PRO and 70% FAT

During 8 weeks both the keto diet group and non-keto diet group trained 4x/week trying to add some muscle. The whole study can be qualified as a “colossal fuck up” for the keto diet group as it gained no lean body mass:

The researchers concluded:

“Regarding to lean body mass, an adequate carbohydrate intake (non-ketogenic or conventional dietary approach), in conjunction with a caloric surplus and a higher protein intake, might be the most viable option for inducing muscle hypertrophy after resistance training.”

So no muscle for the folks on the keto diet group.

Now, if you started the keto diet in hopes of building a 0% body fat physique, don’t drive a knife straight through your thigh just yet — maybe it’s just one study and it’s wrong. So let’s see another one.

A 2021 study by Paoli et al. investigated the impact of the keto diet on competitive natural bodybuilders. The researchers concluded that:

Ketogenic diet may be used during bodybuilding preparation for health and leaning purposes but with the caution that hypertrophic muscle response could be blunted.

So hindered muscle growth for keto diet once again (I told you this is going to be a rough experience for keto zealots).

And I’m not done yet — compromised lean body mass gain in resistance trainees on the keto diet has been observed in more studies than the amount of carbs you are allowed to eat on keto (including a 13-study systematic review & meta-analysis by Ashtary-Larky and colleagues):

Ketogenic diets combined with resistance training interventions may increase the rate of fat mass loss in athletes, but compared with non-ketogenic diets, it is not an appropriate dietary approach for increasing muscle mass. While ketogenic diets may be helpful in endurance performance, it is an oxymoron when athletes seek to boost muscle hypertrophy

You may be thinking to yourself, But Egis, why does the keto diet inhibit muscle growth? It’s presented to people as if it was some kind of sorcery, after all…

No worries, I will explain.

In short (because I’m hungry and need to go eat my oats), the anabolic hormonal response seems to be blunted during a keto diet and this may explain the reduced muscle growth response that was observed in the studies (the source).

In Sum

So what does it mean to you? Is the keto diet a pant-load? Absolutely not.

For one, the keto diet does a good job at spontaneously making you eat less. So, food gates are open — no more. Which is a good thing when it comes to weight loss. And even though I just ranted about how keto is all a bunch of fluff for muscle growth, I don’t think it’s that bad.

You see, most studies I shared looked at advanced lifters with multiple years of resistance training experience under their belts. For this population, gambling with keto is a very fucking stupid idea knowing that when it comes to muscle growth, the weight of the evidence robustly favors higher carbohydrate intakes.

But if you are just a fresh off the couch beginner lifter, I don’t think the keto diet is going to be an issue. ‘Cuz noob gains, you know; pretty much any dietary approach you throw at a beginner lifter will work as long as resistance training and higher protein intake are implemented.

So while the keto diet represents everything that I hate (I do find it highly entertaining though), I think that unless you chase a bodybuilder-like body composition, you can still get a kick-ass body following it.

Like I said in this post, sustainability is the most critical factor for any diet and if keto is something you enjoy, who cares if you miss out on a few extra pounds of muscle?

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Originally published by me on Medium on May 31, 2022

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