Illustration of a skinny guy eating oatmeal and a banana to build muscle.

How Many Carbs Should You Eat to Build Muscle?

Carbs have come under fire lately. Low-carb and keto diets are all the rage. But those are fat-loss diets, and the reason we’re being told to avoid carbs is that they make it easier for some people to gain weight. What if you’re trying to gain weight? What if you’re trying to build muscle? How many carbs should you eat?

Before and after results of a skinny guy gaining weight with a fast metabolism.

What Are Carbs?

There are three macronutrients: protein, carbs, and fat. All of them contain energy, and so all of them can help us gain weight. That doesn’t mean they’re all the same, though.

  • Protein helps our immune systems, and is used to build our hair, nails, bones, and muscle. If we lift weights and eat enough calories, eating enough protein will help us build muscle. Extra protein is almost never stored as body fat.
  • Carbs are used as a fast source of energy. They’re broken down into simple sugar and stored in our livers and muscles as glycogen. This glycogen makes our muscles fuller and harder, and it gives us more energy. Having more glycogen also speeds up our rate of muscle growth. Extra carbs are almost never stored as body fat.
  • Fat is used to help us aborb some vitamins, regulate our hormones, and is easily stored as body fat. We use this body fat as a longterm source of energy. It’s important to eat enough dietary fat and have enough body fat. It’s just that many people have too much body fat.

Will Carbs Make You Gain Fat?

No, carbs don’t cause fat gain. They taste good, though, and processed carbs can be an easy way to pack in calories. If you eat too many calories, you’ll gain weight. If you gain too much weight too quickly, or if you aren’t following a good workout program, you might gain more fat than muscle. But you aren’t gaining that fat because of the carbs, it’s because of the calories.

In fact, carbs and protein are almost never stored as body fat. The conversion process is too costly. They’re more likely to be burned off as body heat, invested in tissue repair/growth, or stored as glycogen. It’s the fat we eat that we store as body fat. Here’s where it gets confusing, though. It sounds like we get fat by eating fat, and that’s true, but it’s not the whole story.

Let’s imagine that you got 90% of your calories from protein and carbs and only 10% from dietary fat. If you eat too many calories overall, your body won’t convert the protein and carbs into body fat, but it will still store some of the fat you’re eating. And it’s not like you can completely remove fat from your diet. You need that fat to help you absorb vitamins and regulate your hormones. Plus, some of the most nutritious foods out there, such as eggs, seafood, nuts, and avocados, are packed full of fat.

So carbs don’t make us gain fat, calories make us fat. And when we eat too many calories, it’s the fat we’re eating that’s most likely to be stored as body fat.

Carbs do help us build muscle, though. And if we eat enough of them, they’re often packed into our muscles as glycogen, making us look and feel stronger.

If You Lift, Carbs Will Help You Gain Muscle

There are three main fields of research concerned with muscle growth: bodybuilding research, strength research, and sports research. In all three fields, virtually all experts recommend that we get around half of our calories from carbohydrates.

  • Bodybuilding: we’re told to get 40–60% of our calories from carbohydrates to increase our rate of muscle growth (studystudy).
  • Strength training: The National Strength & Conditioning association recommends that we get 45–65% of our calories from carbohydrates to help us gain more muscle mass and strength.
  • Sports performance: The Journal of the International Society of Sports Nutrition recommends eating enough protein to build muscle, enough fat to absorb vitamins and reglate our hormones, and then getting the rest of our calories from carbohydrates to speed up muscle growth, give us more energy, and improve athletic performance. Usually that works out to getting around 20–30% of our calories from protein, 20–30% from fat, and 50–60% from carbs.

So, to summarize, if you’re trying to gain muscle mass, strength, or improve your athletic performance, then you should get around half of your calories from carbohydrates.

How Important Are Carbohydrates?

There’s no doubt that eating plenty of carbohydrates will help you build more muscle. Still, you don’t need to be that precise about it. A wide range of carb intakes can be good for building muscle. Even if you’re following the research to the letter, you can still get anywhere from 40–65% of your calories from carbs.

Also, keep in mind that you don’t need to fully optimize your diet. You can eat in a way that you enjoy. If that means eating a bit more fat or protein, that’s fine. It won’t have a big impact on your results. It’s not a major factor.

The most important factors are:

  • Training for muscle size. The most powerful muscle-building stimulus comes from exercise—from resistance training. The style of resistance training designed to help you build muscle is called hypertrophy training.
  • Eating enough calories to gain weight. Overweight people can build muscle while losing fat, especially if they’re new to lifting weights. But if you’re skinny, as I was, then there’s only one way to go from 130 pounds up to 190 pounds—you have to gain weight.
  • Eating enough protein. Muscle tissue is made from protein. But remember that protein is also used for your immune system, and for building hair, nails, bones, and repairing muscle. If you aren’t eating enough protein to maintain everything else, your body won’t have any extra to invest into muscle growth. We recommend eating at least 0.8 grams of protein per pound bodyweight per day. So if you weigh 130 pounds, that’s at least 104 grams of protein per day.
  • Getting enough good sleep. When you get enough good sleep, you have more energy, more willpower, greater insulin sensitivity, and produce more testosterone. You also build more muscle. That’s why we recommend getting 7–9 hours of sleep every night.

Carbs are important, too. Don’t get me wrong. But before you start worrying about using calorie trackers to optimize your carb intake, worry about getting the basics down. You can build plenty of muscle even if you aren’t eating tons of carbs. Plenty of people do. But carbs do help.

What Carbs Should You Eat?

The best bulking diets are made up mostly of whole foods. Unprocessed carbs are some of the most nutritious foods out there, packed full of phytonutrients, fibre, vitamins, minerals, and antioxidants. As such, the best sources of carbohydrates are:

  • Fruits, such as bananas, passion fruits, mangoes, papayas, oranges, and squash.
  • Dried fruits, such as raisins, dried cranberries, dried cherries, and dried mangoes.
  • Berries, such as frozen mixed berries, blueberries, cherries, and blackberries.
  • Starchy vegetables like potatoes and sweet potatoes.
  • Squash, such as pumpkin.
  • Legumes, such as beans, lentils, green peas, and soybeans.
  • Dairy (and alternatives), such as milk, yogurt, and soy milk.
  • Whole grains, including oats, rice, quinoa, whole wheat, and corn.
  • Honey.

I’ve underlined the foods that are most popular with bodybuilders, but you can get your carbs from any of those foods. You can also get carbs from processed foods like pasta, white rice, and whole-grain bread. Those foods don’t tend to contain as many phytonutrients or as much fibre, but they can still be part of a balanced diet, especially if you’re eating them alongside other whole foods.

If you’re having trouble eating enough carbs, try snacking on bananas, blending up some fruit and yogurt smoothies, having some muesli or oatmeal for breakfast, or having larger servings of rice, beans, or potatoes with your meals.

How Many Carbs Should You Eat?

You should get around 40–65% of your calories from carbs when trying to build muscle. Eating plenty of carbs will give you more energy, make your muscles fuller and harder, and increase your rate of muscle growth.

Just remember to keep everything in perspective. It helps to eat lots of carbs, but that doesn’t mean you need to track your macros or micromanage your carb intake. Just think of eating plenty of fruits, berries, starchy vegetables, beans, lentils, soy, yogurt, and whole grains. If most of your meals have a source of carbs in them, you’ll do great.

Illustration showing the Bony to Beastly Bulking Program

If you want more muscle-building information, we have a free bulking newsletter for skinny guys. If you want a full foundational bulking program, including a 5-month full-body workout routine, diet guide, recipe book, and online coaching, check out our Bony to Beastly Bulking Program. Or, if you want a customizable intermediate bulking program, check out our Outlift Program.

Shane Duquette is the co-founder and creative lead of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's personally gained sixty pounds at 11% body fat and has nine years of experience helping over ten thousand skinny people bulk up.

Marco Walker-Ng is the co-founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell, and is a certified trainer (PTS) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. His specialty is helping people build muscle to improve their strength and general health, with clients including college, professional, and Olympic athletes.