British long-distance runner Jake Smith has described a repeating pattern of race, illness and injury that dogged him before he learned the cause was Relative Energy Deficiency in Sport, or REDs, and that he had been under-fuelling. Smith did not know his energy intake was falling short of what his training demanded, so the cycle kept repeating. He is the only person named in the account, and the details of when he was diagnosed and how he treated it have not been disclosed.
How the cycle kept repeating
The pattern is the same one a lot of endurance athletes know: get fit, race, fall ill, pick up an injury, start again. Smith kept returning to racing, and the problems kept coming back. What he didn't have was an explanation. REDs gave him one. It's a condition tied to chronic under-fuelling, where the body doesn't get enough energy for what training and daily life demand, and the consequences show up across systems rather than in one spot.
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For Smith, those consequences came as repeated setbacks rather than a single obvious injury. He wasn't aware of it. That's a key part of the story — the condition can build quietly, and the runner may not connect it to what they're eating.
What REDs actually is
Relative Energy Deficiency in Sport is the clinical term for a sustained mismatch between energy intake and the energy training plus basic body function require. The condition is recognised across endurance sports and is not specific to running. Diagnosis depends on recognising the pattern, not on a single test, which is why it's easy to miss.
Smith's case fits that description: a body repeatedly breaking down in different ways, with no single cause at first glance. Under-fuelling doesn't present as a fracture or a virus. It presents as one setback after another until someone spots the pattern.
The energy question that doesn't go away
Endurance athletes at the elite end routinely run on tight margins between what they burn and what they take in, and the difference between fuelled and under-fuelled can be small enough to miss in a normal training week. REDs is the name for what happens when that margin is crossed for long enough.
Smith's account adds a name and a public profile to a condition that often stays private. The specifics of his calorie deficit, his treatment and his return to competition are not part of the record, so there's no way to judge how severe his case was or how quickly he recovered.
What's still unresolved
Smith has not said when he was diagnosed, how long he had been under-fuelling or what changed once he knew. Those gaps matter, because REDs cases are often described only after the athlete has already come back — the timeline is what would help other runners spot the same pattern in themselves.
For now the record is short: a British distance runner, a repeating cycle, and a diagnosis that explained it. The next thing to watch is whether Smith or his team put a date and a treatment plan on the record.
