A Client Just Showed You a €180 Supplement Stack. Here's How to Triage It in 60 Seconds.

How we sourced this. Every claim below is tied to a named study — a meta-analysis, an umbrella review, a product audit, or the live trial registry — and linked. We grade each item: where the evidence is strong, we say so; where it’s thin, we say that louder. This piece was reviewed for accuracy before publishing and carries a real byline, because on health topics a citation you can’t stand behind is worse than no citation at all. Last updated 14 September 2026.

The shelf is the problem, not any single tub

You know the moment. A client opens their phone and shows you a screenshot of a cart: creatine, a pre-workout, BCAAs, a “natural test booster”, fat burner, and a protein tub. Two hundred euros. They want you to say it’s a good stack.

Here’s the thing that makes this hard: answering item by item takes twenty minutes and you’ll lose them by minute four. What you need is a triage — a way to sort the shelf into piles fast, and be right.

So we did the boring, valuable thing. We pulled the meta-analyses and umbrella reviews behind each major category, plus the product audits that nobody reads, and sorted them. The result is smaller than the shelf and much cheaper.

Three things earn a default yes for a general training population. One earns a conditional yes. The rest of the cart is either situational or noise.

Tier 1 — the default yes

Creatine monohydrate

This is the least interesting recommendation in fitness and it’s still the right one. A 2024 meta-analysis of 23 studies found creatine plus resistance training added +11.35 kg to lower-body strength versus placebo.² A 2026 network meta-analysis of 52 trials put it plainly: creatine alone produced the most consistent improvements across sprint, jump, repeated-sprint and upper-body muscular endurance outcomes, out-ranking the alternatives it was compared against.³

Five grams a day, plain monohydrate, timing irrelevant. A few cents. It’s the single best cost-to-evidence ratio on the shelf.

Evidence grade: Strong. Decades of replication, consistent direction, multiple meta-analyses.

Protein — but only if there’s a gap

This is where most coaches get the triage wrong, in a way the client will feel in their bank account.

Protein supplementation works. Across 49 randomised trials and 1,863 participants, adding protein to resistance training improved 1RM strength by +2.49 kg and fat-free mass by +0.30 kg.¹ Real, but modest — and read the second half of that paper, which is the part that matters: gains stopped entirely once total protein intake passed ~1.62 g/kg/day.¹

Translate that for the gym floor: protein powder is not a drug, it’s a delivery van. If your client is already hitting their intake from food, another scoop does nothing measurable. If they’re at 0.9 g/kg because they skip breakfast and eat lunch at their desk, the powder is genuinely useful — as the cheapest way to close a food gap.

So the first question isn’t “which protein”. It’s “what are you actually eating?” That question is free, and it’s the highest-value thing you’ll do in the conversation.

Evidence grade: Strong for the effect; strong for the ceiling too. Both halves are from the same well-replicated meta-analysis.

Caffeine — for the session, not for the shelf

Caffeine is the most robustly supported acute performance tool there is. An umbrella review of 21 published meta-analyses found it ergogenic across aerobic endurance, muscular strength, muscular endurance, power, jumping and speed — with the certainty of that evidence generally graded moderate.⁴ The ISSN position stand puts the consistently effective dose at 3–6 mg/kg, usually about 60 minutes before the session.⁵

Two coaching notes the marketing never gives you. First, the effect is biggest in aerobic work, not in the bench press.⁴ Second, the dose is per kilogram, which means a 55 kg client and a 95 kg client are not taking the same scoop — and the same position stand notes that very high doses (~9 mg/kg) come with more side effects and no extra benefit.⁵

And the honest caveat that keeps you out of trouble: if it wrecks their sleep, it is a net negative for their training, full stop. Caffeine is a tool for a specific session, not a daily habit you coach someone into.

Evidence grade: Strong for the effect, moderate certainty across outcomes; effect size varies a lot between individuals.

Tier 2 — the narrow, conditional yes

Beta-alanine

Beta-alanine isn’t a scam. It’s just far narrower than the tub suggests. Across 40 studies and 1,461 participants, the overall effect size was 0.18 — small — and the benefit was concentrated almost entirely in efforts lasting roughly half a minute to ten minutes.⁶

Two things that should change how you recommend it. A 2026 network meta-analysis compared creatine, beta-alanine, and both together, and found beta-alanine’s effects were non-significant or context-specific, with no synergistic benefit from stacking it on top of creatine.³ So the “creatine + beta-alanine” combo product your client is holding is, on current evidence, a creatine product with an extra price tag and a tingle.

Who it’s actually for: the rower, the 800 m runner, the CrossFit athlete, the fighter — anyone whose sport lives in that two-to-eight-minute burning window. Your general-population client doing three full-body sessions a week is not that person.

Evidence grade: Moderate, but narrow. Real effect, tightly bounded by effort duration.

Tier 3 — the pile you can clear today

This is the part that saves your client the most money, so don’t rush it.

BCAAs, if protein intake is adequate. The marketing rests on a mechanism: BCAAs switch on the signalling pathway for muscle protein synthesis. That part is true. The problem is that building new muscle protein needs the full set of essential amino acids, and BCAAs only supply three of them — so the review literature concludes the claim that BCAAs alone produce an anabolic response in humans is unwarranted.⁷ A client already eating enough protein is buying an expensive subset of what they already have. (If their protein intake is genuinely low, the fix is protein, not BCAAs.)

“Testosterone boosters”. This is the easiest no you will give all year, and the numbers are almost comic. An audit of 50 products found 90% claimed to boost testosterone — while only 24.8% had any published data supporting that claim, 10.1% contained components with data showing a decrease, and no data existed at all for 61.5% of them. Thirteen products exceeded the tolerable upper intake level for ingredients like zinc, niacin or magnesium.⁸

Multi-ingredient pre-workouts and fat burners. Not because a stimulant before training can’t help — see caffeine — but because of what else tends to be in the tub. Which brings us to the question that outranks everything above.

Evidence grade: Strong that the claims aren’t supported. This isn’t “we don’t know yet”; it’s “it’s been looked at.”

The question that matters more than efficacy: is it clean?

Coaches argue about effect sizes and skip this entirely, which is backwards.

In 2022, Sport Integrity Australia had 200 sports supplements bought from the Australian online marketplace and analysed. 35% contained WADA-prohibited substances — mostly stimulants. And the part that should make you sit up: 57% of the products containing prohibited substances did not list them as ingredients anywhere on the packaging or website. The categories most likely to be contaminated were pre-workouts, fat burners and muscle builders.⁹

That’s roughly one in three products off the shelf, in a regulated market, with a majority of findings undeclared.

For a competing athlete, that’s a career risk — strict liability means “I didn’t know” is not a defence. For everyone else, it’s simply undeclared stimulants in a body they didn’t consent to. Either way the fix is the same and it’s boring: only buy products with third-party batch certification. That is the single recommendation in this entire piece with the best risk-to-effort ratio, and the review literature lands in the same place — check the label against the prohibited list, don’t stack products with overlapping ingredients, and choose verified products.¹⁰

If you coach a tested athlete, this stops being advice and becomes a duty of care. Send them to their sport’s dietitian or doctor before they take anything.

Evidence grade: Strong. Multiple independent market screens, consistent findings.

The hole in the whole shelf

Here’s the caveat that belongs on every recommendation above, and almost never gets said.

A 2022 audit went through the research behind the six most evidence-backed performance supplements — beta-alanine, caffeine, creatine, glycerol, nitrate and sodium bicarbonate. Across 1,826 studies and 34,889 participants, just 23% of participants were women. Fewer than one in ten of those studies attempted to define menstrual status at all.¹¹

This doesn’t mean the advice is wrong for female clients. The direction of the evidence almost certainly holds. But the precision — the dose, the response size, whether it shifts across a cycle — is not established to the same standard, and pretending otherwise is exactly the kind of confidence that erodes trust when a client eventually reads the study themselves.

Say it out loud: “This is well established, and most of the research was done on men. Here’s what we’ll watch.” That sentence makes you more credible, not less.

Evidence grade: This is a gap in the evidence, not a finding. Treat it as a confidence discount, not a contraindication.

What’s about to be proven

Here’s what a static supplement chart can’t give you: the live edge.

Right now the trial registry lists 41 studies recruiting or about to start that test creatine, whey, or a protein supplement against muscle loss in weight loss, obesity or sarcopenia.¹² And the pattern inside them is the story: three different items from your client’s shelf are being pointed at the same problem — muscle lost during medication-driven weight loss.

Three named examples, all live:

• A pilot trial of creatine plus resistance training to prevent lean tissue loss during GLP-1 receptor agonist therapy (NCT07625202, recruiting).
• A multicentre RCT of whey protein plus resistance training in adults aged 45+ on incretin-based weight-loss medication, 180 participants over six months (NCT06950684).
• A Phase 2 trial of HMB plus vitamin D during semaglutide-associated weight loss in older adults (NCT07760948).¹²

Read that as a coach, not a scientist: the supplement conversation with your clients is about to reorganise itself around a question that didn’t exist five years ago. Nobody can claim any of these are proven for it yet — these trials read out in 2027 and beyond. But the coach who understands the question before the answer arrives is the coach who gets trusted when it does.

That’s also why this page carries a date. We update it when the pipeline delivers.

Your script for Monday

When the next client hands you the €180 cart, here’s the whole triage in plain language:

“Let’s cut this down. Keep the creatine — five grams a day, cheapest plain monohydrate you can find, it’s the best-evidenced thing in here. Keep the protein only if you’re actually short on protein from food; let’s check that first, because above a certain intake the powder stops doing anything. Caffeine before your hard sessions is fine and it works, but it’s dose-by-bodyweight, not a daily habit, and not if it costs you sleep. The BCAAs, the test booster and the fat burner all go — the test booster shelf in particular has almost no data behind it. And whatever you do keep: buy the version with third-party batch testing on the label, because about a third of products tested off the open market had undeclared substances in them. That last bit matters more than anything else on this list.”

That’s it. No hedging, no bro-science, no overpromising. You just saved them most of the money and all of the risk — which is the entire job.

Sqwod reads the research so your clients don’t have to. This is coaching information, not medical advice; anything involving a medical condition, pregnancy, or medication — including weight-loss medication — belongs with a qualified professional. Spotted something that needs sharpening? That’s how an evidence page stays honest — tell us and we’ll correct it in public.