While I agree that muscle anabolism is 'optimal' with heightened IGF and insulin levels, there has been members who have claimed that they HAVE built muscle on a low carb/keto style diet regimin. Simply, it becomes a matter of getting in enough calories to promote muscle gain. This may become harder on a low carb diet because your food choices to eat decreases. I believe cockdezl has answered this question as well in the past (probably many times
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I do agree with most that adding carbs to your diet for muscle gain is the way to go, but to say it is impossible to gain muscle without them, is not true by other peoples real-world results.
Controlling insulin may be a factor to losing fat and gaining muscle, but it ultimately comes down to calories in vs calories out.
BMJ

I do agree with most that adding carbs to your diet for muscle gain is the way to go, but to say it is impossible to gain muscle without them, is not true by other peoples real-world results.
Controlling insulin may be a factor to losing fat and gaining muscle, but it ultimately comes down to calories in vs calories out.
BMJ