A handful of supplements have solid evidence behind them for building muscle, but the list is shorter than the supplement industry would have you believe. Creatine monohydrate and protein powder top the list, with beta-alanine playing a supporting role for people who train at high volumes. Beyond those, the returns drop off quickly.
Creatine Monohydrate
Creatine is the single most studied and effective supplement for gaining muscle. It works by keeping your muscles supplied with quick-burst energy, helping them contract harder during heavy lifts. That extra energy lets you squeeze out more reps and handle heavier loads over time, which is what drives muscle growth. The supplement pulls water into muscle cells as well, creating a fuller appearance and an environment that favors growth signaling.
The standard protocol is 3 to 5 grams per day, every day, with no need to cycle on and off. Some people do a “loading phase” of 20 grams per day for five to seven days to saturate their muscles faster, but you’ll reach the same saturation point within a few weeks at the lower dose. Creatine monohydrate is the form to buy. Fancier versions (hydrochloride, buffered, liquid) cost more and perform the same or worse in studies.
One persistent concern is whether creatine harms your kidneys. A systematic review and meta-analysis found that creatine supplementation does not induce renal damage at studied doses and durations. Kidney markers stayed within normal ranges across both short-term and long-term studies. If you have an existing kidney condition, that’s a different conversation, but healthy people can take creatine without worrying about their kidneys.
Protein Powder
Protein powder isn’t magic. It’s a convenient way to hit your daily protein target, which is the real driver of muscle growth. People who lift regularly need roughly 1.2 to 1.7 grams of protein per kilogram of body weight each day. For a 180-pound (82 kg) person, that works out to about 98 to 139 grams. Anything above 2 grams per kilogram is considered excessive and doesn’t provide additional muscle-building benefit.
If you can hit that range through whole foods like chicken, eggs, Greek yogurt, and legumes, you don’t need a protein supplement at all. But most people find one or two scoops a day makes the math easier, especially on busy days or right after training.
Whey vs. Casein vs. Soy
Whey protein digests fast and causes a sharp spike in blood amino acid levels, particularly leucine, the amino acid that most strongly triggers muscle repair. In a study published in the Journal of Applied Physiology, whey boosted muscle protein synthesis roughly 122% more than casein and 31% more than soy after resistance exercise. Casein digests slowly, releasing amino acids over several hours, which is why some people take it before bed. Soy falls in the middle on both speed and effectiveness.
For most people, whey is the best default choice. If you’re lactose intolerant or vegan, soy or pea protein blends are reasonable alternatives. The type of protein matters less than the total amount you eat across the day.
The Anabolic Window Is Overblown
You’ve probably heard you need to chug a protein shake within 30 minutes of your last set or you’ll “miss the window.” A 2025 systematic review with meta-analysis found that protein timing does not meaningfully change gains in lean body mass. There is no conclusive evidence that consuming protein immediately around exercise maximizes muscle growth compared to simply eating enough protein throughout the day. Spread your intake across three or four meals and don’t stress about a post-workout countdown.
Beta-Alanine
Beta-alanine helps with a different piece of the puzzle: endurance within your sets. Your muscles produce acid as they work hard, and that burning sensation eventually forces you to stop. Beta-alanine raises levels of a buffering compound inside your muscles by as much as 80%, which delays that burn and lets you push through more reps before fatigue hits. More reps at a challenging weight means more total training volume, and volume is a key driver of muscle growth.
The recommended dose is 5 to 6 grams per day, split across meals (about 2 grams with breakfast, lunch, and dinner). The splitting matters because a large single dose causes a harmless but annoying tingling sensation on the skin. Results aren’t immediate. It takes over 12 weeks of consistent supplementation for muscle carnosine levels to fully saturate, so this is a long-game supplement. Beta-alanine is most useful for people doing high-rep training, circuit-style workouts, or sports that demand repeated bursts of effort.
EAAs vs. BCAAs
Branched-chain amino acids (BCAAs) were one of the most popular gym supplements for years, but the evidence has shifted. BCAAs contain three amino acids: leucine, isoleucine, and valine. They can reduce muscle breakdown during exercise, but they cannot fully promote muscle protein synthesis on their own because the process requires all nine essential amino acids working together.
Essential amino acid (EAA) supplements contain all nine, making them more effective at stimulating muscle growth and recovery. That said, if you’re already eating enough protein from whole foods or whey, you’re getting all nine essential amino acids anyway. EAA and BCAA supplements are most useful for people who train fasted or who struggle to eat enough protein. For everyone else, they’re an expensive redundancy.
Supplements With Weaker Evidence
HMB
HMB is a compound your body naturally produces from leucine. It’s marketed as an anti-catabolic supplement, meaning it’s supposed to prevent muscle breakdown rather than directly build new tissue. A randomized controlled trial in critically ill patients found that HMB reduced net protein breakdown and improved amino acid metabolism, but did not significantly reduce overall muscle wasting over 10 days. In healthy, trained lifters, the effects are minimal. HMB may offer a small benefit for beginners experiencing significant muscle damage from new training stimuli, or for people in a caloric deficit trying to preserve muscle, but it’s far from essential.
Citrulline Malate
Citrulline malate increases blood flow to working muscles by boosting nitric oxide production. The proposed benefit is more reps per set and reduced soreness. The commonly cited dose is 8 grams taken before a workout. Some users report better “pumps” and modest improvements in rep performance, but the overall body of evidence is still developing compared to creatine or protein. It’s a reasonable add-on for experienced lifters who’ve already nailed the basics, not a starting point.
Vitamin D
Low vitamin D levels are associated with weakness and poor muscle function, so correcting a deficiency matters. However, supplementing vitamin D when your levels are already adequate does not appear to boost muscle growth. A randomized, placebo-controlled trial giving 2,000 IU of vitamin D daily to older adults for eight weeks found no effect on muscle protein synthesis rates compared to placebo. Vitamin D is a health supplement, not a muscle-building supplement. Get your levels checked if you suspect a deficiency, but don’t expect it to add size.
What Actually Matters Most
No supplement replaces progressive overload, adequate calories, and sufficient sleep. Creatine and protein are the only two supplements with strong, consistent evidence for directly supporting muscle growth in healthy people who train regularly. Beta-alanine earns a supporting role if your training style involves high reps or sustained effort. Everything else sits in the “nice to have” category at best.
If your diet already provides 1.2 to 1.7 grams of protein per kilogram of body weight daily, your training program progressively increases in difficulty, and you sleep seven or more hours a night, adding 3 to 5 grams of creatine monohydrate daily is the single highest-impact supplement decision you can make. Start there before spending money on anything else.