5 Supplements to Avoid If You’re Trying to Gain Muscle

Walk into any supplement store, and you’re immediately hit with a wall of products promising quick fixes, but many of these claims can be misleading or even downright harmful. And if your goal is to build muscle (which happens to be one of the most common goals I hear from athletes as a sports dietitian), it’s important to know which ones to steer clear of.

Now, I’m not saying all supplements are bad. There are plenty I recommend and take personally. But many folks looking for supplements go on an uninformed supplement shopping spree. That’s why I teamed up with a few fellow sports dietitians to break down the top 5 supplements to avoid if you’re trying to build muscle.

1. Appetite Suppressants 

If you’re pushing yourself every day at the gym, you’ve probably noticed a rumbling stomach (which is completely normal!). Active people need more calories than those with a sedentary lifestyle, and if muscle gain is your goal, you’ll need even more to support growth. However, some athletes may ignore those hunger cues and instead turn to appetite suppressants to quiet their rumbling stomachs. 

“It’s a common misconception that reducing food intake is essential for building muscle or improving body composition, but that’s not necessarily true,” explains Briana Butler, MCN, RDN, LD. “Appetite suppressants can hinder muscle gain because they often reduce your ability to consume the necessary nutrients for growth,” she says. 

Butler explains that using appetite supplements can have the opposite effect—slowing or even halting muscle growth altogether. On top of that, some of these appetite suppressants may contain harmful or unregulated ingredients that could pose serious health risks, including life-threatening outcomes. Instead of blunting your appetite, learn how much you actually need to eat to support muscle growth by meeting with a sports dietitian. 

2. Weight and Mass Gainers 

If muscle growth is the goal, picking up a weight or mass gainer might seem like a logical solution, but board-certified sports dietitian Kelly Jones, M.S., RD, CSSD, recommends otherwise. “Many mass gainers, also known as weight gainers, are high in saturated fat and calories while displacing other nutrients you need for general health and muscle building,” she explains.

Jones points out that some of these supplements contain over 1,200 calories per serving and lack essential nutrients such as fiber, unsaturated fats, vitamins and minerals. Taking either a weight or mass gainer could actually lead to people gaining fat mass instead of muscle mass, she notes. 

Not only is increasing calories important for gaining muscle mass, but also the quality of those calories. Focus on incorporating nutrient-dense foods, such as lean proteins, whole grains, fruits, vegetables and heart-healthy unsaturated fats. 

3. High-Dose Antioxidant Supplements

While loading up on vitamin C may seem like a smart move to protect your immune system, especially with all the germs floating around the gym, taking high doses can actually backfire when it comes to making muscle gains. 

“Research shows chronic high-dose supplementation with vitamins C and E may blunt your training gains,” explains Marie Spano, M.S., RD, a sports dietitian. She advises athletes to steer clear of high doses of vitamin C, E and other high-dose antioxidant supplements. 

“These antioxidants can interfere with muscle growth by decreasing the actions of free radicals—molecules that, while often seen as harmful, play a crucial role in signaling processes that drive muscle hypertrophy,” she adds. In other words, some free radicals are needed to help trigger muscle growth.

Your best bet for getting a healthy dose of antioxidants: focus on eating a rainbow of colorful fruits and veggies that are naturally chock-full of them.  

4. Hormones or Prohormones

If you’re pushing yourself hard at the gym and not seeing results after weeks, it’s easy to wonder if something’s off, like a hormone imbalance. This may lead some individuals to order themselves a hormone or prohormone supplement. 

“Supplementing with hormones or prohormones without necessity may lead to short-term gains, but over the long term, it can negatively affect the body’s natural hormone production,” says Butler. 

Testosterone does help promote muscle growth and prohormones help boost hormone levels, but using either without a doctor’s order can be problematic. Research shows that prohormones don’t significantly increase testosterone levels and may lower HDL-cholesterol (known as your “good” cholesterol), which isn’t good news for your heart health.

Butler explains that this hormone disruption can hinder muscle growth and may also have adverse effects on other organs, such as the heart, liver and kidneys. “These supplements have grown in popularity, especially alongside efforts to build muscle, but consuming them without clinical guidance can be risky,” she warns. So, only take hormones or prohormones if instructed and prescribed by your healthcare provider. 

5. Pre-Workout Supplements

If you’re looking for an energy boost to make it through your next workout, a pre-workout supplement may seem enticing. While these supplements are popular among those who go to the gym often, many of the ingredients aren’t well-regulated, warns Jones. 

“Niacin is often in pre-workout supplements in doses above the tolerable upper intake level, resulting in ‘flushing’, a rush of blood to the skin’s surface and a pins and needles-like feeling,” explains Jones. While niacin is a B vitamin essential for energy metabolism, high doses aren’t linked to better exercise performance. Instead, that flush sensation may simply create a placebo-like effect for those hoping for muscle gains, she says.

Pre-workouts may also contain proprietary blends (a red flag!) that companies slap on supplements, hiding certain ingredients or amounts. Another concern is the high levels of caffeine commonly found in pre-workout supplements, which can be especially risky for young folks, those with caffeine sensitivities and during pregnancy. 

If you’re looking for a safer pre-workout option, Jones recommends sticking with a cup of coffee. As caffeine has been associated with improved muscle strength and power, minus the sketchy other ingredients.

Our Expert Take

Building muscle takes time and patience. It’s essential not to resort to unhealthy measures or look for shortcuts to achieving your goals by taking questionable supplements. With thousands of products on the market, it’s hard to know which supplements are truly safe and effective. Sports dietitians recommend avoiding these five supplements if you’re trying to gain muscle. Working one-on-one with a sports dietitian is the best way to receive personalized nutrition guidance, select safe supplements and reach your health and fitness goals.