High-carb diets are often recommended to promote muscle growth from strength training. But are carbohydrates really that important for muscle growth? A new meta-analysis provides the answer.
THE IMPORTANCE OF CARBOHYDRATES
Yes, carbohydrates have several important functions when it comes to muscle growth: they are the primary energy source for strength training, they stimulate the release of the hormone insulin, which is important for muscle growth, and they reduce the release of the catabolic stress hormone cortisol.
But should you therefore consume as many carbohydrates as possible?
THE RESEARCH
Researcher Menno Henselmans and his colleagues delved into the literature for their meta-analysis and identified eleven relevant studies. These studies compared higher versus lower carbohydrate intake and reliably measured muscle growth in healthy adults, primarily trained individuals, taking energy and protein intake into account.
THE RESULT
While some carbohydrates before training can improve your performance (especially with high training volumes, see below), the reality is that you don’t really need to consume massive amounts of carbohydrates if you’re training purely for muscle growth. Carbohydrates aren’t as important for muscle growth as is often thought and claimed.
THE EXPLANATION
Unlike endurance training, where carbohydrate intake is much more important, it seems that when building muscle, you should focus primarily on protein and calories in general. The explanations:
- Mechanistically, protein and adequate total energy intake make carbohydrates largely irrelevant, as protein already stimulates all of the anabolic and anti-catabolic processes that carbohydrates do, including insulin;
- Strength training doesn’t burn that many carbohydrates, generally no more than 40% of stored glycogen.
The timing of carbohydrate intake isn’t that important either, as you might have read in this and this article. After all, your muscles rely primarily on their stored glycogen, not on the glucose in your blood from your last meal.
THE EXCEPTIONS
An earlier systematic study by Henselmans, from 2022, also showed that carbohydrates generally do not improve strength training performance.
There are exceptions, as it turns out, namely when you do more than 10 sets per muscle group in a single workout, train twice a day, or train fasted. Otherwise, you won’t deplete a muscle’s glycogen stores to the point that contractile function is impaired, and there will be sufficient time to replenish glycogen stores before training that muscle again.
THE CAVEATS
The above doesn’t mean you can’t safely eat a lot of carbohydrates. However, the results of the two meta-analyses warrant some caveats:
- While eating lots of carbohydrates won’t necessarily speed up muscle growth, that doesn’t mean you shouldn’t consume large amounts of carbohydrates as long as you enjoy them and it fits within your calorie budget;
- You still need to get enough fiber for your health. Some of that fiber can come from carbohydrate-rich foods;
- Some carbohydrate-rich foods, such as oatmeal and others, have unique benefits for overall health.
CONCLUSION AND ADVICE
In general, carbohydrates don’t seem as important for muscle growth as often thought, as long as you consume enough calories for your goal and meet your protein needs. The numbers:
- The number of calories is slightly above your maintenance level in the bulk (+10-20%), in the cut slightly below that (-20-25%);
- The protein requirement for a serious natural bodybuilder is around 2 grams per kilogram of body weight per day;
- Fats are also certainly not unimportant: consume 1 to 1.5 g/kg/d;
- What remains are carbohydrates, which usually amounts to 2-4 g/kg/d.