Gluten, lactose and the fighter who cut a food group for no reason

Forty-one percent of athletes without coeliac disease avoid gluten at least half the time. That figure comes from a survey of 910 athletes, from recreational level up to Olympic. Most of them decided on their own.

For a fighter that decision costs more than it does for anybody else.

What the trials found

The foundational work compared a gluten-free diet against a gluten-containing one in athletes who did not have coeliac disease.

No benefit to performance. No benefit to gastrointestinal health. No difference in inflammation. No difference in perceived wellbeing.

A systematic review published in 2024 put it more bluntly: no studies support a gluten-free diet for reducing gastrointestinal symptoms in athletes.

That is a rare thing in nutrition, a question with a clean answer, and the market has ignored it for a decade.

So why do some people feel better

Because they are right about the symptom and wrong about the cause.

Removing gluten-containing grains also removes a large quantity of FODMAPs, short-chain carbohydrates that ferment in the gut and draw water into it. Fructans, which wheat is full of, are among the most common.

So the athlete who cut bread and felt better did feel better. They attributed it to the wrong molecule, and then cut far more food than they needed to.

The scale of this is worth seeing. In the same survey work, 55 percent of those 910 athletes had eliminated at least one high-FODMAP food to reduce gut symptoms, and 83 percent of that group reported the symptoms improving.

FODMAPs are the mechanism with evidence behind them. Gluten is the label that took the credit.

The trap nobody warns about

This is the practical point that matters most on this page.

Coeliac disease is diagnosed while you are eating gluten. Both the blood tests and the biopsy look for a response to it.

Remove gluten from your diet first, and those tests can come back normal in somebody who genuinely has the disease.

So the athlete who quietly goes gluten-free for 6 months, feels somewhat better, and later wants to know for certain has locked themselves out of the answer. Getting it then requires a gluten challenge: deliberately eating gluten again, typically for a minimum of 6 weeks at a sufficient daily amount, before the tests mean anything.

Protocols vary, and plenty of people refuse once they hear what it involves.

Lactose is a different problem

Lactose intolerance is a reduced capacity to digest lactose, different from an allergy or an autoimmune disease; it varies enormously between populations, and it is dose dependent.

Dose dependent is the part fighters get wrong. Most people who cannot manage a large glass of milk handle yoghurt, hard cheese, or a small amount of dairy taken with a meal perfectly well.

The threshold is individual and usually higher than somebody assumes after one bad evening.

Cutting all dairy on the strength of that evening removes a dense source of protein and calcium from a diet with little room to spare.

Fight week is a separate matter. Dairy comes out then for reasons of gut content and digestibility rather than intolerance. That is a temporary tactical decision, not a permanent verdict on the food.

Why this costs a fighter more

Any elimination narrows a diet. In most sports there is room for that.

A fight camp has no room. The diet narrows through the phases by design, and by fight week it is deliberately reduced to a short list of easily digestible foods. Micronutrient intake falls with food volume, which is a separate cost of the same decision.

Now remove a whole grain group on top of that, or all dairy, for a condition nobody ever confirmed. You have taken a narrow diet and made it narrower, in the phase where it is already thinnest, for no established benefit.

I have had fighters arrive at camp having removed three food groups. None tested. All of them on advice from somebody in the gym.

What I actually do

• Rule out coeliac disease properly, while they are still eating gluten. A doctor, not a guess.
• Look at what is happening around the symptoms. In a camp, gut trouble is frequently about training in heat, dehydration, eating too close to a session, caffeine on an empty stomach, or anxiety before competition. Food gets blamed for all of it.
• If food does look like the trigger, a structured low-FODMAP elimination with a professional, followed by systematic reintroduction. Reintroduction is the point. An elimination without it is not a diagnosis, only a smaller diet.
• Revisit it. Tolerance changes. A food that caused problems in a heavy block may be fine in the off-season.

When it is real

None of the above applies if the condition is genuine.

Coeliac disease requires complete lifelong gluten avoidance, and there is no safe dose. A diagnosed food allergy is a medical matter carrying a risk of serious reaction, and not something to experiment with.

Both need a plan built around them rather than a plan they are subtracted from.

In both cases the real work is the same: replacing what was removed, not simply removing it. A coeliac fighter still needs the carbohydrate. A dairy-free fighter still needs the calcium and the protein.

The elimination is the easy half, and it is the half most people stop at.

The sentence I repeat most often

An unconfirmed intolerance is a diagnosis you gave yourself, and you are unlikely to be right.

Forty-one percent of a large athlete sample removed a food group they had no reason to remove. Some of them felt better, for reasons they misidentified.

Most of them made their diet worse in a sport where the diet is already under pressure.

Get tested. Then decide.