What a supplement can and cannot do

The real order of magnitude: how much a supplement adds next to training, eating and sleeping. And why that order decides where the money should go.

The supplement industry sells a comfortable story: that some tub closes the gap between what you do and what you would like to get. The evidence tells a less marketable and far more useful one: a handful of products genuinely work, they work a little, and they only work once everything underneath is already in place.

This guide treats supplements as what they are: the top layer of a stack. Before looking at any product it is worth knowing how thick that layer is.

The hierarchy, in proportion

This is not a motivational metaphor: it is the rough share of the outcome attributable to each lever in someone who trains seriously. Supplements exist, they count, and they are the small slice.

Four questions before you buy

They work for any product, including ones released after this was written. If any of them answers no, the rest are moot.

1. 1

   Is the base sorted?

   Weekly volume per muscle and progression (training variables), calories that match the goal (how many you need), protein covered and sleep. Buying before that is paying for the 3% while ignoring the 50%.

2. 2

   Is there evidence in humans, training, at the dose in the tub?

   Most claims come from studies in cells, in rats, or at doses ten times what the product contains. A plausible mechanism is not a measured effect.

3. 3

   Does it happen to people like me?

   Many effects only show up in specific populations: people deficient in a nutrient, vegetarians, women low on iron, over-60s. Outside those groups the average effect is usually zero.

4. 4

   What does the effective dose cost per month?

   Not the tub: the daily dose the studies used, for as long as they used it. That is the calculation that eliminates half the catalogue without arguing about physiology.

What a supplement is and is not

Legally, in the European Union a food supplement is food, not medicine. That has two big consequences worth having clear before reading any label.

• Efficacy does not have to be proven before selling. A medicine goes through clinical trials and an authorisation; a food supplement does not. What is regulated is what it may say: health claims must be on the European register, evaluated by EFSA. That is why labels talk in circles.
• The contents do not have to be proven either. Control is after the fact and by sampling, not before and by batch. Hence the chapter on quality and contamination, which in this guide is not an appendix.
• A supplement is not a substitute. A protein shake, a carbohydrate drink or a gel are food in a convenient format; they count inside the day’s calories and compete with the rest of the plate, they are not free.

How this guide is organised

Criteria first, then products by family, and the buying decision last. Each chapter stands alone, but this order is the one that saves money.

Fundamentals

What to expect · What actually works · Quality and labels

The framework: how much a supplement can move, and what a tub guarantees.

Protein and amino acids

Protein types · Amino acids

The best-selling family and the most misunderstood.

Performance

Creatine · Caffeine · For running

The ones with a measured effect, with their doses and their limits.

Health and buying

Vitamins and minerals · What does not work · How to buy

The part that is not about performance, and the final decision.