Supplements to Avoid — The Ones That Waste Money or Risk Health
The supplement industry sells roughly ten products that work, a hundred that do nothing, and a handful that are actively harmful — and the marketing for all three categories looks identical. The difference is the evidence, and it is almost never on the label. This guide names the categories to avoid, explains why, and shows how to vet anything you do buy.
The starting point is a useful rule: if a supplement promises a result that sounds too good (lose fat while eating anything, gain muscle without training, detox your liver), it is either lying or dangerous. The products that work — protein powder, creatine, caffeine — make modest claims, because modest claims are what the evidence supports.
Use the calculator
Start with the numbers: try our protein calculator and the macro calculator to work out your own figures before applying anything on this page. The worked examples below use round numbers so you can follow the maths; the calculators use your real weight, height, age and goal.
Related reading: protein calculator, macro calculator, Creatine Guide — Benefits, Dosage, Safety and Myths, Muscle Gain Diet — Calories, Protein and Meal Structure. You can also browse the full guides section for the rest of the series.
The key points
Proprietary blends: paying for a secret. A 'proprietary blend' lists a total weight for several ingredients without saying how much of each is inside. That means the product can contain an effective dose of nothing and a trace of everything, and you cannot tell — the label is designed to hide it. Effective ingredients have known doses (creatine 3–5 g, caffeine 200 mg, citrulline 6–8 g), and any product that will not state its doses is not worth buying. If the dose is not on the label, assume it is too low to work.
'Testosterone boosters' and hormone products. Over-the-counter 'testosterone boosters' — usually tribulus, fenugreek, D-aspartic acid or similar herbs — have little reliable evidence of raising testosterone in healthy men, and none of them raises it enough to build muscle. Products that actually do raise testosterone are medicines, not supplements, and they carry real medical risks. Worse, some 'natural' testosterone products have been found to contain undeclared prescription drugs or anabolic steroids, which is why several have been recalled. If your testosterone is genuinely low, that is a medical issue for a clinician, not a supplement aisle.
Detox teas and 'cleanses'. Detox teas are usually senna or another laxative, plus caffeine: they make you lose water and bowel contents, which looks like weight loss on the scale for a day and does nothing for fat. Your liver and kidneys detox your body continuously, and no tea improves on them. Regular use of laxative teas causes dehydration, electrolyte disturbance, cramps and dependence — the bowel stops working normally without them. The weight they 'lose' returns as soon as you eat and drink normally, because it was never fat.
Stimulant fat burners and DMAA. Fat burners are usually high-dose caffeine plus a mix of stimulants, and their effect on fat loss is tiny (caffeine itself helps slightly, and you can get it from coffee for a fraction of the price). The danger is the dose and the extras: some products contain very high caffeine (400 mg or more per serving), synephrine, or DMAA (dimethylamylamine), a stimulant that has been linked to heart attacks, strokes and deaths and is banned by regulators in several countries and by WADA. Any product that makes your heart race, makes you anxious or keeps you awake is not 'working' — it is overdosing you.
Mega-dose BCAAs and 'muscle' amino products. Branched-chain amino acids (leucine, isoleucine, valine) are three of the nine essential amino acids, and they are sold as a muscle-building supplement. The problem is that muscle building needs all nine essential amino acids, not three — taking BCAAs alone is like delivering bricks without mortar. A complete protein (whey, soy, or a meal with meat, eggs or legumes) provides all nine for less money. BCAAs are only defensible in the narrow case of someone who cannot eat protein around training, and even then a complete protein powder is better and cheaper.
How to vet any supplement before buying. Three checks cover most of the risk. First, third-party testing: look for NSF Certified for Sport or Informed Sport on the label, which means the product has been tested for banned substances and label accuracy. Second, transparent dosing: every active ingredient listed with its amount, no proprietary blends. Third, a plausible claim: if the evidence for an ingredient is real, the claim will be modest (creatine: 'supports strength'), not miraculous. And one rule for everything: if you take prescription medicine, have a medical condition (especially kidney or liver disease), or are pregnant, check with a clinician before taking any supplement.
At a glance
| Product | Problem | Better alternative |
|---|---|---|
| Proprietary blends | Doses hidden; usually under-dosed | Single-ingredient products with stated doses |
| Testosterone boosters | Little evidence; some contain undeclared drugs | Medical advice if testosterone is genuinely low |
| Detox teas | Laxatives; water loss, not fat; dependence risk | Water, fibre, sleep |
| Stimulant fat burners | High caffeine, sometimes DMAA; heart risk | Coffee (200 mg caffeine) if wanted at all |
| BCAAs | Incomplete amino acids; poor value | Whey, soy, or a protein meal |
| 'Muscle' / 'shred' stacks | Bundled under-dosed ingredients at a premium | Protein + creatine, bought separately |
Your plan, step by step
- Check the label: every active ingredient listed with its amount — no proprietary blends.
- Look for third-party testing (NSF Certified for Sport or Informed Sport).
- Ignore miracle claims; real supplements make modest claims.
- If you take medicine, have kidney or liver disease, or are pregnant, ask a clinician first.
- Spend the money on food and training first — protein and creatine cover almost everything useful.
The formula behind it
The value test for a supplement is a cost-per-effective-dose calculation: cost per day = price ÷ servings × doses needed per day, compared with the dose the evidence supports.
Worked example — a 'muscle stack' at £40 for 20 servings, with 1 g of creatine per serving (the evidence dose is 3–5 g): you would need 3–5 servings a day, so the real cost is £6–10 a day, or £180–300 a month, for a dose you could get from plain creatine monohydrate at a few pence a day. The same maths exposes most blends: divide the price by the servings, multiply by the servings needed to reach the evidence dose, and compare with the single-ingredient price. If the product will not state its doses, the calculation cannot be done — which is itself the answer. Use the protein calculator to check whether your daily protein (1.6 g/kg for lifters) is already covered by food before spending anything on supplements.
How to use this guide
The pattern that works is the same for every topic on this page: understand the principle, apply it for two to four weeks, and judge it by what changes — not by how it feels on day one. Most fitness and nutrition advice fails not because it is wrong but because it is applied for three days and then abandoned. Pick the one or two changes from this guide that fit your life, do them consistently for a month, and only then decide whether they are working. If you try to change everything at once, you will not know what helped, and you will not sustain any of it.
Related pages on this site go deeper on the numbers behind this guide: the calculators apply the same formulas shown here to your own weight, height, age and goal, and the protein, macro and body-composition articles work through the maths for specific cases. Use this guide for the understanding and the calculators for your own figures — neither replaces the other.
What this guide does NOT tell you
No guide can replace individual advice. The numbers and ranges on this page are population estimates from published research, and they describe what works on average — your body, your health conditions, your medicines and your training history all shift the answer. This guide does not diagnose anything, prescribe anything, or predict your results. If you have a medical condition (especially heart disease, diabetes, kidney or liver disease, an eating disorder, or a hormone condition), are pregnant, or take prescription medicine, the right next step is a clinician or a registered dietitian, not a more detailed article.
The other limit is honesty about evidence. Some claims in fitness are supported by randomised trials; others are supported by tradition, by a single small study, or by nothing at all. This guide says which is which where it matters, and where the evidence is thin it says so rather than dressing a guess up as a fact. A guide that admits uncertainty is more useful than one that pretends to know everything — and a reader who knows the limits of the advice is safer than one who follows it blindly.
Frequently asked questions
Are supplements regulated?
Less than medicines. In most countries, supplements do not need pre-market approval for safety or efficacy — the manufacturer is responsible, and regulators act after problems appear. That is why third-party testing (NSF Certified for Sport, Informed Sport) matters: it is the only independent check that the product contains what the label says and no banned substances. Without it, you are trusting the manufacturer's word.
Which supplements are actually worth taking?
For most people who train, the short list is: protein powder (a convenience, not a necessity), creatine monohydrate (3–5 g a day, the best-supported supplement for strength), and caffeine (about 200 mg before training, if tolerated). Vitamin D is worth considering in winter or with low sun exposure, on a clinician's advice. Everything else is situational or unsupported — which is why this guide exists.
Are fat burners dangerous?
Some are. The main risks are very high caffeine doses (400 mg or more per serving, which can cause heart palpitations, anxiety and sleep disruption) and undeclared or banned stimulants such as DMAA, which has been linked to heart attacks and strokes and is banned in several countries and by WADA. The fat-loss effect of even the safer fat burners is tiny compared with a calorie deficit. A cup of coffee gives you the caffeine for a fraction of the price and without the extras.
Do detox teas work for weight loss?
No — they cause water and bowel loss, which looks like weight loss on the scale for a day and returns as soon as you eat and drink normally. They do not burn fat, and they do not 'detox' anything: your liver and kidneys do that continuously. Regular use risks dehydration, electrolyte disturbance and bowel dependence. The weight they appear to lose was never fat.
How do I know if a supplement is safe?
Check three things: third-party testing (NSF Certified for Sport or Informed Sport), transparent dosing (every ingredient with its amount, no proprietary blends), and a plausible claim. Then check with a clinician if you take prescription medicine, have kidney or liver disease, are pregnant, or take other supplements — interactions are the risk most people miss. If a product fails any of the three checks, do not buy it.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.