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Can Carbs Be Fuel for My Muscles, Too?

I’m eating as much protein as I can, but I’m dying to put some of it on a slice of bread

Around the time I was doing my most dedicated push to acquire muscle, I was inundated with information suggesting that protein was the sole nutrient necessary for gaining muscle mass. On the flip side, carbs were said to only be for fueling lengthy workouts, and if you didn’t burn off those carb-derived calories, they were quickly gonna be repurposed around your waist. As such, I didn’t eat carbs for a very long time, swapping them out completely for the supposed almighty protein. 

The thing is, we live in a world where nutritional information is often conflicting and poorly sourced, and it’s common for those of us who ought to know better to fall victim to some of the worst disinformation imaginable. I certainly did. Because my understanding of carbs was both oversimplified and totally incorrect. In fact, you actually have a far tougher time building muscle when you avoid carbs like the plague.

How do carbs help build muscle?

For what it’s worth, the official position of the International Society of Sports Nutrition is that consuming a combination of protein and carbs after heavy resistance training leads to the greatest overall development of lean muscle mass as well as the greatest improvement in body fat percentage.

Why? For starters, carbs are critical to the building of muscle due to the fact that they’re the only food source that’s quickly and efficiently stored as glycogen in your muscles. And glycogen is the most immediate source of energy that your muscles rely upon, since your body typically won’t begin to break down stored body fat into energy until roughly 30 minutes into an aerobic workout. Protein and dietary fat can both be used to generate muscle glycogen under less-than-ideal circumstances, but additional steps are required to cause that transformation. 

Second, when taken after a workout in tandem with protein, carbs can cause insulin levels to rise to a higher degree than proteins alone, and the increase in insulin results in the faster delivery of amino acids and glycogen to the muscles. Basically, carbs will accelerate post-workout muscle recovery and growth compared with situations when protein is consumed alone, at least under most circumstances.

Also, a study from the Netherlands demonstrated how followers of a carb-restricted diet excreted larger quantities of nitrogen than individuals on other diets, indicating that the bodies of those individuals are breaking down muscle for energy in the absence of carbs. This suggests that not only are carbs vital contributors to muscle growth, but their absence will accelerate the loss of the muscles you already have.

But don’t carbs also contribute to more body fat?

They can, but that statement also presupposes that all carbs are created equal. 

Carbs that are prepackaged with a lot of fiber move through your system very slowly and won’t dramatically spike your insulin levels, which is what would cause your body to quickly convert those calories to body fat. Moreover, these kinds of carbs — like broccoli and carrots — are usually notably low in calories. 

Meanwhile, simple sugars are also carbs, but they tend to be one of the two most problematic sources of carbohydrate intake. By drinking 20 ounces of fully loaded Mountain Dew, you’ll immediately spike your insulin while contributing nothing toward your level of fullness, leaving you with a major hankering for additional calories. 

Speaking of additional calories, starchy carbohydrates like potatoes, rice and cereal grains are the other carb problem children. A fortified cereal may be a valuable carbohydrate source when consumed in manageable amounts, but a punch bowl filled with Lucky Charms isn’t doing you any favors. Likewise, a single baked potato consumed as one component of a balanced meal is helpful, but a serving of Five Guys french fries will easily launch you into the caloric stratosphere.

It sounds like carbs are helpful as long as I control my servings and watch what kind of carbs I eat.


It’s always good to remember that very specific (or limiting) diets are generally prescribed by medical professionals for those who are dealing with serious health issues or are intended for elite athletes whose careers are often determined by millimeters or microseconds. Unless you fall into one of these categories, an obsession with food ratios is unnecessary. 

Because the other thing you should always keep in mind is that all three macronutrient sources — proteins, fats and carbohydrates — are essential for every physical process, including muscle growth. It’s when you believe that you won’t upset your body’s balance by completely eliminating an entire food source that you’re writing a recipe for disaster.