Which supplements work? Creatine, caffeine, protein powder

Three supplements are worth knowing about if you lift. Creatine monohydrate, 3–5 g a day, adds a little extra strength and lean mass.^[1][2] Caffeine, about 3 mg per kg of body weight (around 200 mg) before training, gives a small boost.^[1] Protein powder is just food. Most of the rest lack good evidence.

The shelf holds a lot of products. An expert panel for the International Olympic Committee (IOC) found good evidence for only a few, with caffeine and creatine among them.^[1] And even those do less than training and food. The panel wrote that supplements "can make a minor contribution" to an athlete's diet.^[1]

The last article covered choosing a goal: cut, bulk or recomp. This one covers what's left on the shelf once the goal, the food and the training are set.

Why the supplement shelf deserves suspicion

Supplements are sold with big promises. The few that have good evidence give a small extra on top of training and food.^[1] For most of the rest, the evidence is thin or missing.^[1]

Money is the smaller problem. In the US, a supplement doesn't have to prove it works, or that it's safe, before it goes on sale.^[1] Some products contain drugs that aren't on the label (more on that below).

The big things still decide your results: training that gets a little harder over time, and enough food and protein. What actually matters when you start lifting covers those. No tub makes up for a program you skip.

What the research says

Who wrote the research we cite

A position stand is a group of experts summing up the research for a professional body. The position stands we cite come from two groups: the IOC and the International Society of Sports Nutrition (ISSN). For caffeine safety we also cite a scientific opinion from Europe's food safety authority (EFSA).

Some well-known position stands have ties to the supplement industry. The ISSN's creatine position stand states that support to prepare it "was provided by the Council for Responsible Nutrition".^[3] Several of its authors declare roles with companies that sell sports nutrition products.^[3] The IOC statement declares no competing interests.^[1]

A declared tie doesn't make a paper wrong. We cite independent sources first where they exist. Where the only direct evidence comes from authors with industry ties, we say so next to it.

Creatine adds a little strength and lean mass

Creatine is a compound your muscles store and use for short, hard efforts. It's sold as a powder. The IOC panel says it improves short, hard efforts, single or repeated. It also raised maximum strength in static tests, where you push against something that doesn't move.^[1]

A meta-analysis pools the results of many studies on the same question into one estimate. A recent one pooled 63 studies with 1,489 people.^[2] Everyone lifted weights. Some also took creatine.

Lean mass means everything in your body that isn't fat. Muscle is a big part of it, but so are water, organs and bone.

Strong evidence that creatine works: an independent meta-analysis and the IOC panel agree.^[1][2] The size is less certain.

The meta-analysis found signs of publication bias: studies with disappointing results may be missing from the record. After adjusting for that, the strength benefit shrank to small-to-moderate for both upper and lower body, but it didn't disappear.^[2] The authors rated the certainty of their evidence as low to moderate.^[2]

The people studied were 18 to 75 years old. About half had never trained, and the trials ran 4 to 12 weeks.^[2]

Fewer studies included women: 248 of the 1,489 people. In women, lower-body strength improved. The upper-body result couldn't be told apart from no effect, and the analysis found no clear difference between the sexes.^[2] Limited evidence for women specifically.

Plain monohydrate, and no loading needed

Every trial in that meta-analysis used plain creatine monohydrate,^[2] and it's the form the IOC panel names.^[1] That's the form with the evidence.

A loading phase means taking a big dose for the first week to fill your muscles fast. The IOC panel describes about 20 g a day for 5–7 days, then 3–5 g a day after that.^[1]

You can skip the loading. In a 1996 study of 31 men, 20 g a day for six days raised the creatine in their muscles by about 20%. Taking 3 g a day got to a similar level over 28 days, just more slowly.^[4] Limited evidence: one small study, in men. The study took muscle samples to measure creatine. It didn't measure strength.

If you do load, your weight may go up 1–2 kg, mostly from extra water the body holds on to.^[1] Water isn't the whole story, though. Strength rose too, over 4 to 12 weeks of training.^[2]

Is creatine safe?

The IOC panel noted no negative health effects with long-term use, up to 4 years, when the usual dosing is followed.^[1] The ISSN position stand reaches the same view for healthy people.^[3] Moderate evidence. Trials longer than a year are scarce, as the next paragraphs explain.

Creatine does change one blood test. It raises creatinine, a waste product that doctors measure to check your kidneys. A high reading can look like a kidney problem on paper.

Two recent meta-analyses looked at this. One pooled 20 randomised trials (in a randomised trial, people are put into groups by chance). Creatinine rose a little with creatine. But eGFR, an estimate of how well the kidneys filter blood, showed no difference.^[5]

The other found a small rise in creatinine, which the authors put down to the body breaking down more creatine rather than to kidney damage. Kidney filtering didn't change significantly.^[6] Moderate evidence.

Two limits matter here. Most of the trials were short. One group of authors calls for trials longer than a year, and the other says safety data beyond a year remain sparse.^[5][6] And none of the studies in the second review included people with kidney disease.^[6]

The hair-loss worry

The idea that creatine causes hair loss seems to trace back to one small study.^[7] In 2009, 20 college rugby players took creatine for three weeks. Their levels of DHT (dihydrotestosterone, a stronger form of testosterone) rose 56% after a week of loading. After two more weeks, DHT was still 40% above the starting level.^[8]

The study didn't measure hair. The worry is that more DHT could mean more hair loss.^[7]

A 2025 trial did. Resistance-trained men took 5 g of creatine a day or a placebo (a dummy powder) for 12 weeks, and 38 finished. The groups didn't differ in DHT or in any hair measure.^[7] Limited evidence: one small, 12-week trial in young men. Three of its authors declare ties to supplement companies, such as advising brands or consulting for supplement makers.^[7]

So the worry rests on one hormone result, seen after a loading phase. A later trial without loading found no rise in DHT. That trial was the first to measure hair, and it found no effect.^[7]

Caffeine gives a small boost

An umbrella review pulls together existing meta-analyses. One looked at 21 meta-analyses on caffeine and exercise. Caffeine improved endurance, strength, muscular endurance (how many reps you can do), power, jumping and speed.^[9]

The authors rated the evidence for strength and muscular endurance as moderate in quality. The effect was generally bigger for endurance exercise than for short, hard efforts.^[9] Strong evidence. Most of the individual studies were done in young men.^[9]

For lifting, the boost is small. A meta-analysis of 10 studies found that caffeine raised one-rep max (the most you can lift once) by a small amount.^[10] The effect showed up for upper-body lifts. For lower-body lifts, it couldn't be told apart from no effect.^[10] Moderate evidence. The authors called for more studies in women.^[10]

How much, and when

The IOC panel gives 3–6 mg of caffeine per kg of body weight, taken about 60 minutes before exercise, as the usual approach. It adds that lower doses, under 3 mg per kg (around 200 mg), taken before and during exercise, can also help.^[1] Expert consensus. This is the panel's view, not a tested finding.

More doesn't help more. Doses of 9 mg per kg or above don't seem to add any benefit. They also make side effects such as nausea, anxiety and poor sleep more likely.^[1]

Responses can also differ. The IOC panel says responses to performance supplements, caffeine included, may vary widely between people, for reasons that include genetics and usual diet.^[1]

EFSA set out what's safe for healthy adults.^[11]

• A single dose of up to 200 mg raised no safety concerns, including within two hours before hard exercise in normal conditions (EFSA didn't cover exercise in heat).^[11]
• Up to 400 mg a day, from all sources together, raised no safety concerns for adults who aren't pregnant.^[11]
• Lower limits apply in pregnancy and while breastfeeding.^[11]

Expert consensus, from a food safety review.

Note the gap between the two sets of numbers. At 70 kg, the top of the 3–6 mg per kg range is 420 mg in one go. That's more than twice EFSA's single-dose figure. So start at the low end.

Protein powder is food in a tub

Whole food can cover your protein. The IOC panel lists protein products as sports foods: a convenient, usually more expensive option when normal food is impractical, such as on a busy day or when travelling.^[1] The ISSN's protein position stand, several of whose authors declare industry ties, agrees: it's possible to get enough protein from whole food, and powder is a practical way to top up.^[12] Expert consensus. This is the panels' view, not a tested finding.

Your daily protein total is what to watch, and food or powder can both get you there.^[12] For the numbers, see how much protein you need.

What doesn't hold up

BCAAs (branched-chain amino acids) are three of the building blocks of protein, sold on their own. A review of 24 studies in athletes and people who train regularly found their benefits for performance and body composition were negligible.^[13] In people who lifted, they did ease muscle soreness after exercise.^[13] Moderate evidence.

So: maybe a little less sore, but little or no extra muscle or strength. If you already eat enough protein, you're already eating BCAAs.

"Testosterone boosters" are products that claim to raise your testosterone. One study looked at the ingredients in the first 50 products a web search turned up. About 1 in 4 ingredients had any study showing a rise in testosterone.^[14] About 1 in 10 had data showing a drop, and most had no data at all.^[14] Thirteen of the products had more of a nutrient, such as zinc, than the upper intake limit set in the US.^[14] Limited evidence: this checked labels against published research. It didn't test the products on people.

Weight-loss supplements (often sold as "fat burners") fared no better. The IOC panel reviewed common fat-loss ingredients. It rated most of them, such as green tea, as having small to trivial effects, and chromium as having no effect.^[1] Expert consensus. This is the panel's view, not a tested finding.

What's actually in the tub

In the US, supplements are regulated like food ingredients. There's no requirement to prove they work, no requirement to show they're safe, and no quality check on what's inside.^[1] The IOC panel says similar rules apply in most other countries.^[1]

That gap shows up in testing. A study from the early 2000s analysed 634 supplements from 13 countries, none of them sold as hormones. About 1 in 7 (94 products) contained anabolic steroids, a type of hormone, that weren't on the label.^[15] Moderate evidence that this happens. The study is old, and the IOC panel points out that studies like it rarely test a random sample of products.^[1]

Independent third-party testing helps. The IOC panel says testing schemes help athletes manage the risk, but there can be no absolute guarantee that any product is safe.^[1] Expert consensus. This is the panel's view, not a tested finding.

How to apply it

These steps turn the research into a routine. Expert consensus. This is coaching practice, not a tested finding.

1. Sort the basics first. Train regularly, add a little over time, and eat enough protein. Supplements come after that, if at all.
2. If you want creatine, take 3–5 g of creatine monohydrate a day. Skip the loading phase. At 3 g a day, your muscles fill up over about four weeks.
3. If you want caffeine, start around 3 mg per kg, about an hour before training. Stay near 200 mg in one go, even if you weigh more.
4. Count all your caffeine. Coffee, energy drinks and pre-workout products add up toward the 400 mg a day. Check the label for the caffeine content.
5. Skip caffeine before evening sessions if it hurts your sleep.
6. Use protein powder only if it's easier than another meal or snack.
7. Leave BCAAs, testosterone boosters and fat burners on the shelf.
8. Buy fewer products, and look for an independent third-party testing mark. It lowers the risk. It doesn't remove it.

Here's step 3 with numbers.

• 55 kg: 55 × 3 = 165 mg.
• 70 kg: 70 × 3 = 210 mg. Call it 200.
• 90 kg: 90 × 3 = 270 mg. That's above EFSA's 200 mg single-dose figure, so stay near 200 mg.

What's practical can differ from the top of the range. The research range goes up to 6 mg per kg. A dose you can sleep after beats a bigger one that wrecks your night.

Common mistakes

• Buying supplements before the basics are in place. The shelf is easier than a program. But training and food do most of the work. Fix those first.
• Loading creatine because the tub says so. People think it works faster or better. It only fills your muscles faster. 3 g a day gets you to a similar level in about four weeks.
• Panicking about a blood test. Creatine raises creatinine, which can look like a kidney problem. Tell your doctor you take it.
• Thinking more caffeine means more strength. It's tempting to double the scoop. Doses of 9 mg per kg or more don't seem to add benefit, and side effects become more likely. Start low.
• Trusting the label. In the US, a supplement doesn't have to prove it's safe before it's sold. Fewer products and an independent testing mark lower the risk.

How Gymbers fits

The Gymbers app has no supplement features. What it tracks is the training and food they sit on top of. The app logs the weight and reps for each set, with last session's numbers beside each set. If you drink a protein shake, add it as your own food, and nutrition logging counts its protein against your daily targets.