Do fat burners contain banned substances?

Of everything a fighter can buy without a prescription, two categories sit above all the others for causing failed tests. Both of them are marketed hardest at exactly the people running a weight cut.

Nobody buys a fat burner in week two of camp. It gets bought in the week when the scale has stopped moving and somebody is tired, hungry and slightly frightened, which is also the week when judgement is worst.

The shelf with the worst numbers

Sport Integrity Australia commissioned an analysis of 200 supplements bought online from ordinary retailers. Not black market products. Protein powders, pre-workouts, fat burners, the kind of thing that arrives in a box with a training programme printed on the side.

Seventy of them held one or more substances prohibited by WADA. That is the one-in-three figure that gets quoted. The part that gets quoted less often is what happened with those 70: in 57 percent, the prohibited substance was not named on the packaging or on the seller's website.

And the risk was not spread evenly across the shelf.

A second body of evidence comes at it from the opposite end. A Norwegian review of 18 years of doping controls, 2003 to 2020, examined every analytical violation in the period. In roughly a quarter of those cases the athlete named a supplement as the source, and where the claim could be tested, evidence supported it about half the time. The products involved were predominantly multi-ingredient pre-workouts, with fat-burning products behind them.

The substances were mostly stimulants, and one stimulant accounted for 16 cases on its own.

Why this category and not the others

Creatine is one ingredient. Whey is one ingredient. A fat burner is eight to 15, often listed as a proprietary blend with a total weight and no breakdown, which means the label legally tells you almost nothing about what is in the tub or in what quantity.

There is also a commercial reason, and it needs understanding rather than being outraged about. A fat burner has to produce a felt effect within about 40 minutes or the customer does not buy it again. Fat loss cannot do that. A stimulant can. So the incentive across the whole category runs towards putting something in that the buyer will notice, and the cheapest way to be noticed is pharmacological.

One substance, several names

Reading the label carefully does not protect you if you only know one name for the thing you are avoiding. Two examples that keep appearing in cases:

• DMAA. Also written as 1,3-dimethylamylamine and as methylhexanamine. One compound, three names, and it is the stimulant behind those 16 cases. Products have also carried it as geranium extract or geranium oil, which is a marketing label rather than a synonym: analyses have not found the compound occurring naturally in geranium in any meaningful quantity, and what is in the tub is synthetic.
• Oxilofrine. Also written as methylsynephrine and as p-hydroxyephedrine. Prohibited, not permitted as a dietary ingredient in the United States, and the subject of regulatory warning letters to manufacturers who kept using it. A sprinter tested positive for it at national trials in 2013, missed that year’s world championships as a result, and attributed the finding to a supplement.

Add BMPEA and the various phenethylamine derivatives, and the pattern is clear enough. A compound gets banned, then reappears under a chemical synonym or a botanical name that sounds like a plant.

What it collides with in fight week

Set the doping question aside and this category still fails a fighter on its own terms.

Stimulants raise heart rate and increase fluid loss. That is the intended effect of a fat burner, and it is being added to a body that is already dehydrated, already low on electrolytes, and already carrying a resting heart rate elevated by the cut. The same argument applies here as to diuretics, and it ends the same way: this is a cardiac question, and the man taking it is about to be hit in the head by a professional.

There is also the arithmetic. Nutrition removes body mass at roughly 0.5 to 1 percent of body weight per week, and 1 percent is the top of that range rather than the normal case. No product on that shelf changes the number meaningfully inside a camp. If the scale has stopped moving in fight week, a fat burner is not the missing piece.

The division was chosen wrong, or the camp was planned wrong, and both of those get fixed months earlier.

If one is going in the bag anyway

Some fighters will use one. The realistic job is to lower the risk rather than to pretend the conversation did not happen.

• Batch-tested only. If the specific batch code is not searchable in a certification registry, it does not go in the bag. What certification does and does not prove is covered in supplement contamination.
• Nothing with a proprietary blend, whatever the certification says about the rest of the product.
• Check every named ingredient individually on Global DRO, not just the brand.
• Keep the tub, the receipt and a photograph of the label. If a test goes wrong, that evidence is the entire difference between a defence and a story.
• Never in fight week. The one week it gets suggested is the one week the cardiovascular load makes it worst.

The week this gets suggested

In 10 years I have never seen this product decide a camp in a good direction. I have seen it suggested many times, always in the same week, always by somebody who means well.

The honest read is that a fat burner is a purchase made to feel like progress at a moment when progress has stalled. If you want the caffeine, take caffeine, at a known dose, from a product with one ingredient on the label.

That conversation is a separate one, and the numbers behind it are in the caffeine article.

Everything else in that tub is either doing nothing or doing something nobody told you about.

No certification programme lists this category, which is itself the answer. What the programmes do cover is set out in the certification comparison.