Are carbohydrates needed to build muscle?

low carb
Lots of bodybuilders, most of them I would say, emphasize the need for a substantial amount of dietary carbohydrates to build muscle. The argument takes one or both of two forms; 1) that you need carbs to perform more intense exercise in the gym; and 2) carbs are needed to raise insulin and stimulate muscle growth. I’ve never found the arguments all that compelling, but then I’m just an average gym rat, not a bodybuilder extraordinaire. So how much truth is there in these statements?

First, as for intensity of workouts. A study was recently published in the Journal of the International Society of Sports Nutrition – which I noted here – which looked at elite level gymnasts. After 30 days on a ketogenic diet, i.e one with a very low carbohydrate content, probably under 50 grams a day, the athletes’ strength and power had not diminished. However, even these elite athletes, who one would presume were already in terrific shape, lost about 2 kg of fat, with a “non-significant” increase in muscle. This shows that if anything, at least for gymnasts, who require a high level of strength, the ketogenic diet was better than their regular diets. The authors conclude:

Despite concerns of coaches and doctors about the possible detrimental effects of low carbohydrate diets on athletic performance and the well known importance of carbohydrates there are no data about VLCKD and strength performance. The undeniable and sudden effect of VLCKD on fat loss may be useful for those athletes who compete in sports based on weight class. We have demonstrated that using VLCKD for a relatively short time period (i.e. 30 days) can decrease body weight and body fat without negative effects on strength performance in high level athletes.

Assuming that the same holds for bodybuilders, let’s move on to muscle hypertrophy. Another recent study found that carbohydrate does not augment exercise-induced protein accretion versus protein alone. In this study there were two conditions: young men performed resistance training followed by ingestion of either 25 grams of whey protein, or 25 grams of whey plus 50 grams of carbohydrate (maltodextrin). Despite the fact that the extra carbohydrate raised blood glucose levels 17.5 times higher and insulin levels 5 times higher (that is, area under the curve) than protein alone, no difference was found in either muscle protein synthesis or muscle protein breakdown.

So as long as you get adequate protein, you’ve maximized the amount of hypertrophy you can get out of resistance training. Protein raises insulin, which is required for hypertrophy, but raising insulin further does nothing.

Finally there’s an interesting new study, one the co-authors of which is Jeff Volek, who’s done so much great work in this area. The effects of ketogenic dieting on skeletal muscle and fat mass. One reason why it’s interesting is that the men in the study were already resistance-trained. Normally in studies like this they like to use newbies, as you see greater results in them; if already trained subjects are used, and there’s a difference between groups, then you know it really worked well.

Twenty-six college aged resistance trained men volunteered to participate in this study and were divided into VLCKD (5 % CHO, 75 % Fat, 20 % Pro) or a traditional western diet (55 % CHO, 25 % fat, 20 % pro). All subjects participated in a periodized resistance-training program three times per week….

Results: the ketogenic diet group gained 4.3 kg lean mass (muscle) compared to only 2.2 kg for the traditional diet group; the ketogenic group lost 2.2 kg of fat, compared to 1.5 kg in the traditional group.

I’d say this last study puts to rest any argument for lots of carbohydrates in weightlifting. The very low carbohydrate ketogenic diet was superior to a diet with 55% carbohydrate. Note that protein percent was the same for both groups.

Finally, there’s a very good book I recommend by the above-mentioned Jeff Volek and co-author Stephen Phinney, The Art and Science of Low Carbohydrate Performance. I discussed it briefly here.

So, no, carbohydrates are not needed to build muscle, and in fact muscle building might be even better without them.


Leave a Comment:

Jason says December 11, 2014

So for 3000 calories, that would be 150g protein, 250g fat and 37g carbohydrate for the low carb diet (in the last study), as far as macro breakdown daily?

For follow-up research, one question might be does this apply to men of all body compositions?

Baron says December 11, 2014

Thanks – very timely article for me. Was on a low carb diet and stopped making gains. Been experimenting with a high carb diet but it makes me feel crappy and hasn’t helped with gains. Anecdotal evidence, I know, but this article helps clarify things.

pwyll says December 11, 2014

My only concern is that these studies are so short. A number of people including the Jaminets and Matt Stone make convincing cases that (a) a baseline level of carbohydrate is essential for the body, (For example, to synthesize sufficient mucus) and (b) very low-carb often works great for six months, after which the wheels come off the wagon as stress levels rise too high. I don’t think you’d see either of these factors affect things much in a one-month study… I do believe the results are real, but I’m concerned about sustainability.

    P. D. Mangan says December 12, 2014

    Thanks for the comment. I don’t necessarily disagree, but much of this is not fully worked out. Internet debates rage over the ketogenic diet. That’s one reason I like to stick to the science. I’m very familiar with Perfect Health Diet and think it’s perhaps the best of the paleo books. That being said, I tend to eat lower carb than the book recommends.

    George Ironthumb says December 19, 2014

    As with anything, your body will not tend to respond with something done to it for an extended period of time. After 2 or 4 or six months, you should play with your macros again and increase your carb intake for a while, then get back to it

Rick says December 12, 2014

Agreed, timely article. Last year, I was overeating and overloading on carbs and I became bloated and puffy. I knew something was amiss and I realized that either my body was not responding well to that much carbs or my body wasn’t digesting my food as fast I had thought. I think it was a mix of both. I switched up to an IF diet later in the year and into this year and decided to eat like I used to–not putting much emphasis on getting macros right and counting calories, but eating full, quality meals, with loads of animal proteins. My body responded well and I lost some weight, though at the same time, I was not eating as much; and not working out. Though it is cliched to say, you really have to listen to your body and dial it in for what you’re working with. I enjoy articles like these that give good primers for people seeking to improve their health. Information is key, but it’s how one approaches that information that it in then become personal knowledge. Good stuff!

    P. D. Mangan says December 12, 2014


the Revision Division says December 12, 2014

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George Ironthumb says December 19, 2014

Thnaks for this article, PD,

By the way correct me if I’m wrong; but however I believe carbs are somewhat used to fuel high intensity moves
(not talking about HIT here) but moves which involve more than one joint:

Singe jointed moves that don’t challenge the nervous system much, tend to consume fat stores. However with heavy multi-joint, compound moves (with high CNS factor) they tend to use up your muscle’s glycogen stores as carbs is a more effective source of high octane energy for high octane moves and lifts.

Thus I think even if you are in a low carb diet, you still need to take in a good amount of carbs at least 2 hours before lifting weights, and carbs in form of rice, brown rice, etc.

Tell me what you think

    P. D. Mangan says December 19, 2014

    Hi George, you are absolutely correct that high intensity moves are fueled by glycogen, or should we say, the mix of glycogen that goes into them is a higher proportion than lower intensity – walking, say, which is fat-fueled. However, a full tank of glycogen isn’t necessary. We have, IIRC, about 2500 calories worth of stored glycogen, and that tank is never empty, even after ketogenic dieting. So we should have more than enough glycogen to fuel a weight session. This doesn’t take into account, however, keto-adaptation, which allows for a higher mix of fat-burning during high intensity exercise. Also, I would say that even if you do eat carbs, you should have enough stored glycogen so that eating them right before a workout isn’t really necessary. As for myself, I eat pretty low carb, but not zero carb, and I probably go in and out of ketosis; I can’t say I notice any difference in the gym whether I eat carbs or not.

    The runners used to be all about carb loading, and now even some marathoners are going ketogenic.

      George Ironthumb says December 20, 2014


      “you should have enough stored glycogen so that eating them right before a workout isn’t really necessary.”

      Indeed. Since the body would need need to like, “carbo load” and saturate for a while.

      Nonetheless I personally find rice very effective, well at least for me.

      And same with some competitive bodybuilders who were sticking to a low carb diet for years. Increasing their carb intake usually increases their muscle gains as well. But most of these mass would come from “muscle saturation” but noenetheless I guess the difference would only be profound for high level bodybuilders and for people whose bodies are accustomed to carb intake.

      And let us not forget that the gains that most of these bodybuilders get could have just come from the “shock” effect of shifting from one diet structure to another – which is why ordinary people see instantaneous health and fat loss benefits with shifting to a cliche diet, then swearing by their effectiveness afterwards, only to find out that sticking to that diet for a while, that the diet “wont seem to work anymore”.

      And as for carbs, I think one of the reasons why it is very healthy to avoid them is because most of the carbs introduced to us in this day and age are usually of foul nature in the first place.

      Think of wheat, grains, junkfoods, extenders, HFCS ridden snacks, GMO products, etc.
      Then avoiding carbs altogether makes one avoid all of these devils of modern society as well.

gender_inflation says December 8, 2015

Do you think that a high-intensity and high-volume exercise regiment would require a higher carb intake? Say, like starting strength/stronglifts or the texas method, where you’re squatting really heavy 3 times a week?

Also, do you think there is a distinction between “dirty” carbs (higher on the glycemic index) or clean carbs (lower)? So let’s say, a lifter who eats rice and white bread versus one who eats quinoa and Ezekiel bread.

    P. D. Mangan says December 8, 2015

    I don’t know, every time this comes up (as it did just now on Twitter) I get some bodybuilder saying “You have to eat lots of carbs!” So what the hell do I know. It’s just peer-reviewed science.

    A recent study by Volek et al found that runners adapted to fat-burning not only burned more fat, but glycogen repletion is the same as in non-fat-adapted runners. Carbs are mostly used to replenish glycogen, but according to this study, aren’t even necessary.

    But in my opinion, working out hard and often may require more carbs for optimal performance. I don’t know. No matter how many times I discuss this topic, no one wants to believe it, and I’m not a champion bodybuilder, so why I think anyone will listen, well, I don’t know that either.

More Muscle Gains and Fat Loss on a Ketogenic Diet - Rogue Health and Fitness says August 9, 2016

[…] Most bodybuilders will tell you that you need carbohydrates to build muscle, or that it’s more effective with carbohydrates, but there are several reasons for thinking that is not the case. […]

Danny says July 17, 2017

I’ve been eating a low carb diet/high protein for about 3 years. I lift weights and do a lot of body weight exercises I am in tip top shape no body fat etc. I started eating oatmeal and adding rice and increasing the amount of carbs in my meals, and I’ve noticed that my muscles are much tighter and I feel more explosive I get better pumps I also feel more aggressive.

what are your thoughts on this. I’m conflicted by everyone saying carbs are bad.
im 30 years old

    P. D. Mangan says July 17, 2017

    Danny, if adding some carbs to your diet helps you, then by all means, do it. People who are in good shape – lean and muscular – and who exercise can consume carbs, and it could help them. In general, my low carb advice is geared to people who need to lose weight. You don’t. So a small to moderate amount of carbs is perfectly OK for you.

danny says July 17, 2017

I’d also like to add that I’ve gotten in shape by reading your blog and following your advice.
I started getting into health/exercise mostly due to your blog almost 4 years ago.
I’ve donated blood 3 times this year and feel incredible the only the thing is I cannot sleep having a hard time with that.

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