Supplements, Ranked by How Much Science Actually Backs Them

The supplement industry is worth hundreds of billions of dollars, but most of what's on the shelf isn't backed by good evidence. A small group of supplements actually work. Most don't. Here's an honest tier list, based on real studies, not marketing.

Walk into any store and you'll see shelves of powders and pills promising muscle, fat loss, energy, and testosterone. Much of it has limited, mixed, or low-quality evidence behind it. Below, everything is graded from S (best evidence) to F (basically just marketing), based on real studies: systematic reviews, meta-analyses, clinical trials, and the official guidance from sports nutrition experts.

One thing to say upfront: no supplement replaces the basics. Training hard, eating enough protein, sleeping well, and staying consistent do most of the work. Supplements are just a small bonus on top of that.

Also, to be clear on scope: this list is about ordinary dietary supplements, the kind you can legally buy at a store, not peptides, SARMs, or anabolic steroids, which are a completely different category with much bigger risks. Most of what's below is safe for healthy adults when used as directed. The one caveat: supplements aren't checked before they hit shelves the way medications are, and the "testosterone booster" category in particular has had real cases of products secretly containing steroids or other undisclosed ingredients. So even within this list, it's smart to buy from reputable brands.

S = strong proof it helps your training. F = the marketing is way bigger than the science.

S The best of the best: tons of proof

Creatine monohydrate. This might be the single most studied and most reliably effective supplement out there, and it's cheap. Tons of studies show it helps you build muscle and get stronger when you're actually training. It works by helping your muscles make energy faster during short, hard efforts, like a heavy set or a sprint. The right dose is 3 to 5 grams a day, every day. You don't need the "loading phase" people talk about, it's optional. One tip: stick to plain creatine monohydrate. The fancier, more expensive versions haven't been shown to work any better.

Creatine is also naturally in meat and fish, and your body makes some on its own too. But getting the 3 to 5 grams a day used in studies from food alone is pretty unrealistic, which is why most people just take it as a supplement instead.

Caffeine. One of the best-proven performance boosters that exists. It can help you go harder for longer, feel stronger, and make workouts feel easier. A good dose is around 3 to 6 milligrams per kilogram of your body weight, taken 30 to 60 minutes before training, though even smaller amounts can help. If you drink caffeine every single day, your body can get a bit used to it, so a lot of people save it for their harder workouts instead of using it constantly.

You don't need a fancy pre-workout drink to get this. Regular coffee can give you that same active ingredient, caffeine, though the dose is a bit less predictable from one cup to another.

A Strong evidence, worth using

Protein powder. Not magic, but genuinely useful. A big review of almost 1,900 people found that using protein powder helps you build more muscle and strength from training. Here's the catch: it only works by helping you hit your daily protein target. Whey, casein, or plant protein are just easy, cheap ways to get there. If you're already eating enough protein from food, a shake on top won't do much extra. Think of it as a convenient tool, not a magic ingredient. That's exactly why it's ranked here and not in S tier: the thing that actually matters is protein, and the powder is just one easy way to get it in.

B Real benefits, worth it for the right goal

Beta-alanine. A well-evidenced supplement with a specific use case. Position-stand and meta-analytic evidence suggests that 4 to 6 grams daily, taken for at least two to four weeks, can improve performance during high-intensity exercise, particularly efforts lasting roughly 1 to 10 minutes. Results are not equally strong across all types of exercise, however, with some studies finding little or no benefit. It works by increasing muscle carnosine, which helps buffer acidity during intense exercise. If your training involves hard intervals, rowing, or other sustained high-intensity efforts, it may help. For pure strength or long, steady endurance, the evidence is much weaker. The tingling you may feel is a common and benign side effect called paresthesia, and it is not what produces the performance benefit.

Vitamin D (if deficient). This one needs a careful explanation. Vitamin D matters a lot for your bones, and fixing a real deficiency is important. Deficiency is more common in winter and in places far from the equator, so it's worth getting tested. But don't treat vitamin D like a performance booster if your levels are already fine. Recent studies on athletes found no real improvement in strength or power from taking extra vitamin D when it wasn't needed. Bottom line: get tested, and only supplement if you're actually low.

Citrulline (also called L-citrulline or citrulline malate). There's real evidence for a small boost in how many reps you can do. One review of 8 studies (137 people total) found that 6 to 8 grams, taken 40 to 60 minutes before training, let people do about 6% more reps. That's a small effect from a fairly small pool of research, but it's specific enough to be worth trying, which is why it's ranked here with beta-alanine and vitamin D instead of lower down: real benefit, small size, useful if you want it, not essential. Some studies also suggest it might reduce muscle soreness, but that part of the evidence is smaller and less clear, so treat it as a maybe.

C A small edge, or depends a lot on your situation

Omega-3 (fish oil, EPA and DHA). Omega-3s are important nutrients your body needs, but taking them as a supplement doesn't do much for healthy people specifically trying to build muscle or perform better. Big reviews have found mixed or limited results for heart health and cognitive (brain-related) outcomes from fish oil pills across many groups of people studied. Eating actual fish and taking a fish oil pill also don't seem to be the same thing. Omega-3 supplements might be worth it if you rarely eat fish, mainly for general health, but most people who eat a normal diet probably don't need to add them. As a performance supplement, it's just not that strong, which is why it's ranked here.

Betaine. A lesser-known supplement with some promising evidence. A 2024 review of 17 studies (317 people total) found that betaine supplements had a real, positive effect on max strength, especially in the lower body (think squats and leg exercises), but not on upper-body strength, sprint power, or muscular endurance. It's not as proven as beta-alanine or citrulline, and the evidence base is still small. But there's more here than in the tiers below, so it's worth knowing about.

D Doesn't add much for most people

BCAAs (branched-chain amino acids). Very popular, but not that useful for most people. The idea sounds reasonable, but if you're already eating enough protein, taking BCAAs on top hasn't been shown to give you extra muscle or strength. A normal protein source already gives you these same amino acids, plus everything else your body needs to build muscle. If you eat enough protein, this is money you could spend on something better.

E Barely does anything, or is just a convenience

Glutamine. This one matters in certain hospital or medical situations, but for a healthy person who trains, the evidence for muscle growth, strength, or recovery is weak or just isn't there. One big review found no real overall benefit for performance or body composition. Your body already makes plenty of glutamine on its own, and a normal diet gives you the rest. As something to help you build muscle or perform better, it doesn't do much.

Mass gainers. Let's be precise about what "doesn't work" means here. A mass gainer will absolutely help you eat more calories, and if you genuinely struggle to eat enough food, that's a real, useful thing. What it does NOT have is any special muscle-building power beyond the calories and protein inside it. A shake with 1,000 calories of protein and carbs works because of what's in it, not because of some secret formula. You can usually copy it for cheaper with regular food, or just blend protein powder with oats, milk, and fruit. So really this should be read as "convenient, but nothing special," not "useless." And check the label, some of these are loaded with sugar.

F The marketing is way bigger than the science

Testosterone boosters. A 2023 review looked at 52 studies covering 27 different ingredients that get marketed as "testosterone boosters." Most of them failed to actually raise testosterone in a meaningful way, with only a few showing any promise, and only in specific groups of people. If you're genuinely low in something like vitamin D or zinc, fixing that deficiency can help your testosterone. But that's very different from taking a random "test booster" pill when your levels are already normal. As a whole category, this is one of the most overhyped things you can buy.

Fat burners. No pill replaces eating fewer calories than you burn, which is what actually causes fat loss. A few ingredients might give you a small boost in calories burned or a bit less appetite, but the effect is small and unreliable compared to just changing your diet and activity. Caffeine is one of the better-supported ingredients often found in these products, and caffeine itself is cheap on its own. The marketing on this category massively oversells what the science actually shows.

The honest bottom line

Short version: creatine and caffeine are the real MVPs, backed by tons of strong evidence. Protein powder is genuinely useful if it helps you hit your protein goal. Beta-alanine, vitamin D (if you're actually low), and citrulline all give real benefits if they fit your goals. Omega-3 and betaine are worth knowing about, but most people probably don't need them: they're more of a small bonus, or a general health consideration, than something essential for training. Pretty much everything below that either does very little, or is way overhyped compared to what it actually does.

And even the stuff that works only helps a little. A supplement is a small bonus, not a shortcut. The things that actually build a strong, healthy body are the boring ones: training consistently, eating enough protein, sleeping enough, and giving it time. Nail those first, then the few supplements that are actually proven can add a little extra on top. Skip the basics, and no powder in the world will make up for it.