How Many Carbs You Should Eat to Build Muscle

Find out from registered dietitians how carbs fuel exercise to help you pack on muscle.

When it comes to complementing your muscle-building efforts in the gym, many people think you need to eat protein, followed by protein, and then more protein. However, the notion that high protein intake alone builds muscle is one of the biggest misconceptions in the fitness world. Instead, your body requires a balanced diet rich in various nutrients from various food sources to optimize muscle building.

Though protein is essential for muscle growth, you also need carbohydrates to fuel your body and muscles for optimal performance. A meta-review published in Nutrients in February 2022 concluded that carbohydrate intake is critical for strength-training performance and recovery. "People believe carbs are only good for fueling your body and not for building muscle. However, this couldn't be further from the truth," says Reda Elmardi, RD, CPT, a registered dietitian, personal trainer and owner of The Gym Goat. "Carbohydrates are the primary fuel source for our muscles. If we don't get enough carbs, our bodies won't have the fuel to build muscle."

While not all carbs are equal, choosing the right carbs can impact your muscle-building progress. Keep reading to discover why carbs are essential for building muscle and how many you should eat daily to promote muscle growth. Plus, we'll dissect the protein-versus-carb debate to determine which nutrient is more important for adding muscle to your frame.

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Why Are Carbs Important for Muscle Growth?

When fueling your muscles for physical activity, carbs are your body's ideal fuel source. As one of the three primary macronutrients (the other two are protein and fats), carbs are essential for several vital bodily processes, per StatPearls. For example, they deliver energy to your muscles, help control blood glucose (sugar), and improve metabolic functions. Additionally, carbs are critical for muscle growth through the following mechanisms.

Glycogen Repletion

When you exercise, your body breaks down glycogen (the stored form of glucose, a carb) for energy to fuel your workouts and help build muscle. "Glycogen stores are broken down into glucose when the body requires energy," explains Elmardi. "If we don't get enough carbohydrates, our muscles won't have the energy to perform at their best. So when we eat food, our bodies break down carbs into glucose for energy."

To fully replenish glycogen stores after a workout, you must consume a sufficient amount of high-glycemic carbs immediately after exercise, then again in 30-minute intervals for four to five hours, says a 2018 study published in Nutrition Reviews.

Prevention of Muscle Loss

"By consuming adequate amounts of carbs, the human body can maintain muscle mass while undergoing weight training," Elmardi states. Muscle requires carbs to function properly, adds Elmardi. In addition, resistance training causes microscopic tears in your muscle fiber and connective tissue. So without sufficient carb intake, your body can't make enough protein to repair the damaged muscle tissue and may catabolize (break down) existing muscle tissue to create energy, causing muscle loss. Therefore, eating plenty of high-quality complex carbs will help prevent muscle loss.

Muscle Recovery

Consuming carbs after a workout promotes recovery, allowing your muscles to repair themselves and reducing the time it takes to heal. Elmardi says, "A lack of carbs after exercise causes the body to use its muscle tissue as a source of energy. This causes the body to lose muscle mass and increases recovery time." Additionally, carbs help reduce fatigue so you can feel refreshed and get that next workout in sooner, per a 2020 article published in the International Journal of Sport Nutrition and Exercise Metabolism.

Is Protein Better Than Carbs?

It's no secret that adequate protein intake is necessary for "making gains" in the gym, but carbs also play a fundamental role in building muscle. While both macronutrients are essential for muscle growth, they work differently in the body. So, you can't say whether one is "more important" than the other since they're both critical for various functions and have different roles in the body.

For example, when you eat protein, your body breaks it down into amino acids that are then used to repair and grow new muscle fibers. "Amino acids are the building blocks of protein. So eating protein is vital for hypertrophic muscle response," explains Kimberly Gomer, M.S., RD, LDN, a registered dietitian and nutritionist at Body Beautiful Miami. "Your body can't create all the amino acid building blocks you need. Therefore amino acids (protein) are an essential part of the diet for muscle growth."

Conversely, carbs deliver glucose to energize your body (and muscles) for physical activity. So while you can still build muscle by eating a high-protein, low-carb diet, you won't achieve optimal physical performance or build as much muscle as you would with sufficient carb intake.

How Many Carbs Should You Eat?

There's no one-size-fits-all approach to carb intake for muscle building. The carbs you need will vary depending on several factors, including your fitness goals, body type, age and training volume. However, Elmardi offers some general carb intake guidelines for optimizing your muscle gains:

  • Consume 8 to 10 grams of carbs per kilogram of lean body weight daily to optimize strength performance and hypertrophy, per the 2022 meta-review as well.
  • Eat a healthy serving of carbs at least one hour before resistance training, immediately following a workout, and again two to three hours after lifting.
  • In general, choose complex carbs over simple carbs to prevent blood sugar spiking.
  • Carbs such as bananas or dates are excellent quick energy sources before a workout.
  • The 2020-2025 Dietary Guidelines for Americans recommends that carbs make up 45% to 65% of an adult's total calories.

That being said, working with a registered dietitian can help you determine the best number of carbs for you.

The Bottom Line

Carbs are an essential macronutrient ideal for fueling your body's cells for physical activity. Besides fueling your body for exercise, carbs help prevent muscle loss and enhance muscle recovery. Consuming enough healthy carbs (with the majority as complex carbs) will provide the energy required to optimize physical performance for resistance training, allowing you to maximize muscle growth. Lastly, ensure you eat enough protein throughout the day, since amino acids (the building blocks of protein) are required for muscle growth.

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