Do You Need Carbs to Build Muscle and Train Hard?

Key Points:

You don’t need to carb-load to build muscle. Gains aren’t powered by rice and pasta alone.
Pre-workout carbs can boost performance, but not nearly as much as many think.
Calories, protein, and hard training build muscle. Carbs are optional.

If you’ve spent any time reading fitness forums or listening to the biggest guys in the gym talking diet, you’ve probably heard that you need to shovel down your carbs to pack on the muscle and be able to train hard.

In this article, I’m going to dissect not one, not two, but three new studies that put these old gym truths to the test.

Table of Contents

What Are Carbs?

Carbohydrates, or affectionately “carbs”, are one of the three macronutrients, along with protein and fat.

When you eat them, your body breaks them down into glucose, which it then uses right away for energy or tucks away in your muscles and liver as glycogen for later use. Glycogen is also the primary fuel source you use when you lift weights.

Unlike the other macronutrients, you don’t actually need carbs for health and general physical performance. Your body can burn fat for low-intensity activity all day, and you can live your entire life without eating a single potato.

But even if your life doesn’t depend on them, carbs have been considered the optimal fuel for athletes since before I was born (late ‘60s/early ‘70s). Recommendations from organizations like the American College of Sports Medicine say that if you train a lot, you should eat your carbs, and plenty of them.¹

For strength training and bodybuilding, research reviews from the 2000s also recommend a high-carb intake, up to 60% of your calories, whether you’re bulking or trying to lose fat.²

So, no wonder many athletes, lifters, and bodybuilders pound down the rice and pasta. However, more recent research casts more than a shadow of a doubt on the old high-carb recommendations, especially for lifters.

Tired of your Tupperware full of rice? Read The 11 Best Carbs for Bodybuilding and Muscle Growth for inspiration (OK, rice is in there, but so is ice cream (yes, you can eat it)).

Keep reading, and I’ll break down three big new meta-analyses and reviews that put the tapioca to the test. Do you really need carbs to build muscle or to perform in the gym?

Here’s what they found and what it means for your meal prep.

Do Carbs Actually Build Muscle?

That’s the big question of the day. To get to the bottom of it, researchers combed through the literature to see if eating more carbohydrates leads to more muscle growth when you keep protein intake equal between groups.³

An image of a shirtless bodybuilder eating rice from a Tupperware container, making sure he gets enough carbs to train hard and build muscle.

Here’s a quick snapshot of the data pool:

The analysis included 11 randomized controlled trials.
There were 227 total participants across the studies.
The average intervention lasted about 8.5 weeks.

The Results

If you own stock in Big Potato, you might want to sit down.

The pooled analysis revealed no significant effect of carbohydrate intake on muscle hypertrophy.

The difference between the high-carb and low-carb groups was statistically non-significant (any differences or relationships are likely just random chance, not the effects of whatever is being studied).

Even when the researchers specifically looked at “isocaloric” trials (meaning the high-carb and low-carb groups ate the exact same number of total calories), the results were still non-significant.

With calories and protein matched, the high-carb groups did not build more muscle than the low-carb groups.

Some studies measured fat-free mass (FFM), which includes water. Since carbs pull water into muscle, it can make high-carb groups look like they gained more muscle even if they didn’t.

In fact, when the researchers ran a subgroup analysis on the studies that used ultrasound (which measures actual muscle thickness, not just FFM), the results favored the lower carbohydrate intakes. The results were non-significant, and there were only two studies, so I don’t think we should draw any conclusions based on those results, but it’s still interesting.

Also, if your muscles get visibly bigger because there is more water in them, that’s not a bad thing at all. If you’re training for aesthetics, it’s very much a good thing. The point is that the actual tests might be less than accurate when they don’t take water into account.

But hang on a minute, why don’t carbs build more muscle?

If carbs give you energy and help you perform better so you can do a little more work in the gym, shouldn’t they automatically mean more gains?

Can Carbs Help You Lift More?

To answer that question, we’re going to have to take a look at two other systematic reviews.⁴ ⁵

The first looks at total carb intake. Does eating a “normal” or high-carb diet day in and day out translate to better lifting performance compared to a low-carb or ketogenic diet?
The second is a preprint (a manuscript shared by the researchers before publication) that examines whether eating or drinking carbs right before a gym workout can boost your immediate performance.

Are you interested in the ketogenic diet and how it works for lifters?

Check out my in-depth guide How to Build Muscle on Keto for all the info you need.

Study 1: Does a High-Carb Diet Improve Strength Training Performance?

In 2022, researchers looked at 17 long-term studies (lasting anywhere from three weeks to three months) that compared high-carb diets to low-carb or ketogenic diets and how they affected performance in the gym.

An image of someone pouring oats into a blender to mix with bananas and protein powder for a weight-gainer shake.

Sixteen out of those studies found no significant benefit of eating more carbs when it came to building strength.

When protein and total calories were matched, lifters on low-carb and keto diets got just as strong as the carb-loaders. The single study that favored high-carb was flawed because the keto group accidentally ate way fewer calories and ended up losing weight.

How is this possible? Well, your body is extremely good at adapting to anything, including the fuel you give it. It can manufacture the glucose it needs from other sources (like amino acids and fats) to refill your glycogen tanks over a 24-hour period through a process called gluconeogenesis.

A typical workout (up to 10 sets per muscle group) only depletes your muscle glycogen by 40% or less, which is well below the threshold where you’d notice any actual drop in performance.⁶ Your body has no problem topping those tanks off before your next session, even if you’re eating zero carbs.

When a High-Carb Diet Can Help Your Performance

Now, I can think of a few exceptions to the above.

Let’s say you’re a CrossFitter doing two workouts a day, or a bodybuilder doing high-volume sessions with 20 sets per muscle group. In that case, low-carb might fail you.

Even if muscle glycogen only drops by around 40% during a normal workout, advanced bodybuilders are not normal.

High-volume training can severely deplete Type II (fast-twitch) muscle fibers, and if you drain those fibers past a certain threshold, your power output and mechanical tension will likely drop off a cliff.⁷

If you allow me to put on my speculation hat, zero carbs might even be better than a few carbs here. When you get keto-adapted after a few weeks without carbs, your body can usually perform very well again and tolerate even high-volume work, whereas with a low-carb diet, you run out of fuel.

Study 2: Do Carbs Before a Workout Improve Performance?

A 2026 meta-analysis pooled data from 16 comparisons across many studies, with a total of 351 participants.

The researchers found that, yes, carbs before training do help, if only a little. They give you a small but reliable boost in your total training volume, basically helping you crank out a little more total work compared to having a placebo. Ain’t nobody wants a placebo pancake.

An image of a bodybuilder in a red apron and a chef’s hat pouring syrup over a stack of pancakes, and for sure getting enough carbs to build muscle.

That pre-workout carb boost is more noticeable if:

You’re in the gym for more than 45 minutes. If your workout is a quick, in-and-out session, carbs don’t have a statistically significant benefit.
You’re lifting first thing in the morning before breakfast. If you’ve been fasting for 8 hours or more, getting some carbs in your system has a positive effect on your training volume.

In short, yes, carbs before your workout can help with a small but meaningful performance boost.

One note: the studies included “recreationally trained and resistance-trained individuals,” but there was no mention of high-level bodybuilders or elite strength athletes.

So, if you allow me to speculate again, bodybuilders doing 20+ sets per body part might benefit more from pre-workout carbs, even if studies haven’t looked at that scenario yet.

That would go some way toward explaining why you see pro bodybuilders on social media sometimes claiming that carbs are as important as protein for building muscle, because it might feel that way.

Carbs Don’t Build More Muscle? Why Is That?

Now that we have the performance part figured out, we can get back to the important question: why don’t more carbs mean more muscle?

On paper, the math seems foolproof:

Carbs before training = better gym performance = more training volume = more mechanical tension = bigger muscles.

The 2026 meta-analysis confirms the first part of that equation. They found “with high certainty” that pre-workout carbs benefit your total session volume.

So, what gives?

Reason 1: The “Small” Performance Boost

While the volume boost from carbs is statistically significant, the researchers classified it as a “small” effect.

In the real world, your pre-workout carb drink might only translate to one or two extra reps across your entire session.

Yes, you’re doing slightly more work, but it is not a night-and-day difference, and over, say, 10 weeks, that bit of extra volume just isn’t enough to register as new muscle tissue on a DEXA scan or ultrasound.

Reason 2: Mechanical Tension Drives Muscle Growth

The primary driver for muscle growth is mechanical tension, not metabolic stress or having more glycogen in your muscles than they know what to do with.⁸

Example:

Low-carb guy does 10 reps and hits muscular failure.
High-carb guy does 11 reps and hits muscular failure.

Both recruit their high-threshold motor units. Both get maximum mechanical tension on their final reps.

And because both took the muscle equally close to failure, the “grow” signal to the muscle is likely practically identical. The number of reps matters less than how much effort you apply.

Reason 3: Your Glycogen Tank Isn’t Actually Empty

As we learned before, a 45-minute workout doesn’t actually empty your glycogen stores to the point where it matters for performance.

You don’t need topped-up glycogen reserves to recruit your high-threshold motor units and create that all-important mechanical tension. Your body already has plenty of stored energy to handle a lifting session, unless that session is something exceptional or you’re not eating enough in general.

Reason 4: The Insulin Theory

Carbs spike insulin, and you do need insulin for muscle protein synthesis, MPS (when your body builds new muscle protein). It also helps glucose and amino acids to enter the muscle cells.

However, protein is what you need to build muscle, and even a small amount of protein spikes insulin enough for maximal MPS.⁹ And there is no dose-response where more insulin builds more muscle here.

You do reduce muscle breakdown more, but contrary to popular belief, there might not be any big benefits to doing so for building muscle. It’s possible that muscle breakdown is just a natural part of a system that prepares your body to add new tissue.¹⁰

Those are the main reasons why the current body of evidence does not consider carbs essential for muscle growth.

But all that being said, I still think that if you’re doing high-volume workouts for more than an hour or if you train first thing in the morning on an empty stomach, definitely give carbs a chance before you dismiss them.

If eating a high-carbohydrate diet allows you to tolerate and recover from 15 to 20 hard sets per muscle group per week without burning out, then yes, those carbs will indirectly lead to more long-term muscle growth because you can handle more muscle-building volume.

Your training volume is a big factor for muscle growth, even if it’s not the main driver, like some claimed a decade ago.¹¹ ¹²

The Calorie Catch: Why You Might Still Want Carbs

Before you throw your rice cooker out the window, there is a big practical caveat here.

An image of a place with a chicken breast, white rice, and broccoli: a typical meal with carbs and protein for bodybuilders trying to build muscle.

Low-carb and keto diets are famous for reducing your appetite and calorie intake. They make you feel full and can cause monotony in your diet, making you want to eat less.

That can be super neat if you want to lose weight or get lean, but not necessarily if your goal is to build muscle.¹³

For example, in one of the studies analyzed in the meta-analysis about carbs and muscle growth, the high-carb group ended up in an estimated 5,000+ calorie surplus over the course of the study compared to the low-carb group, simply because they ate more food.

To build muscle, you generally want to be in a caloric surplus, or at least in balance. It can be done in a deficit, but it’s much harder.

In a strict lab setting where researchers force-feed the keto group to match the high-carb group, the gains would likely be equal. Keto itself isn’t bad for muscle growth.

But in the real world, the keto lifter might get full after eating a steak while the high-carb lifter effortlessly crushes a 1,000-calorie stack of pancakes. Over a year, the guy who doesn’t struggle to get his calories is going to build more muscle.

Story Time: Personal Reflections

I’ve coached lifters who felt and performed great on high-carb diets and others who hit PRs and built a ton of muscle on steak and eggs.

And over my 38 years of training, I’ve done both approaches myself. I’ve done high-carb in different ways: both basing my diet on “good” carbs like brown rice and sweet potatoes (which is a chore and a half on a bulk) and loading up on pancakes and pie.

But I’ve also gone down the keto route for a full two years.

The first two to three weeks on zero carbs were crummy to say the least, but after that, I really couldn’t tell the difference in the gym. And it was the same with muscle growth and body fat. No magic differences. No differences at all, in fact, that ultimately couldn’t be traced back to training, calories, or protein.

But in the end, I couldn’t stay away from the carbs. Or rather, I didn’t want to. I love me some ice cream too much. And that’s the best part of it all: I don’t think anyone has to choose unless they want to. And the science seems to agree with me.

Final Rep

Time for a one-paragraph summary:

Current evidence does not support the idea that carbs are an independent factor for muscle growth. As long as you eat enough calories and get your protein, you don’t need to force-feed carbs to grow.

However, I should mention that the researchers graded the certainty of said evidence as “low,” because not all studies were of the highest quality and there was some risk of bias. In other words, future research is still needed to give us a definitive final answer.

But for now, the best diet for muscle growth is the one that allows you to train hard, hit your protein goals, and comfortably get your calories in, whether that means some carbs, plenty of carbs, or almost no carbs.

And remember that all these findings are good news whether you’re team high-carb, team low-carb, or perhaps even team keto.

It has never been easier to eat the way you prefer, because carbs mostly matter if they matter to you.

Do you feel like a zombie in the gym without a pre-workout banana or your pasta dinner? Great. Keep the carbs.
Do you feel clear-headed and powerful lifting on a low-carb steak-and-eggs diet? Also great. You can absolutely build muscle without carb-loading.

As long as you’re eating enough total calories, getting your daily protein, and pushing your sets close to failure, your body will build muscle whether that energy came from a high-carb diet or not.

Eat a diet that makes you feel strong, full of energy, and that you can stick with.

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Last reviewed: 2026-02-24