Like all sports, cycling is not immune to the waves of training trends, all promising the marginal gain of that extra one percent. In some cases, for good reason; there is solid scientific evidence to support a given supplement or training protocol, demonstrating marked improvements across various metrics. However, in other cases, the evidence surrounding it is murky, hidden behind good marketing, team endorsement or outspoken advocates. In both cases, its prevalence across the peloton begins to soar, all the way down to recreational riders of the world scrambling to add it to their ever growing regimen.
If you have been even on the periphery of cycling culture the last number of years, one of these ‘trends’ has been impossible to ignore; Ketones. The dark liquid or small shot seen to be downed by riders having crossed the line, shrouded in repeated controversy despite being a now undeniably key component of the elite’s arsenal. What really is this inescapable elixir and does the recreational rider stand to benefit from it?
You may be surprised to learn that you already have your own supply of ketones circulating in your bloodstream, just at very low levels. They are produced by the liver when levels of carbohydrate in the blood are low, and levels of fatty acids are high; a situation synonymous with periods of endurance exercise. Except these ketones produced by the body are known as endogenous; the ketones taken by athletes are a lab made supplement known as exogenous ketones, particularly in the form of ketone esters or the more affordable salts.
In the state of ketosis, it was discovered that the body uses ketones as a source of fuel as opposed to glycogen. Initial interest in its exploitation dates back to the American Department of Defence at Oxford University researching ways to nutritionally support their troops fighting on the front lines, with rations increasingly sparse, as a way to sustain their energy.
Jump forward to the 2010s and the Keto diet became the latest member of mainstream diet culture. Promoting a higher fat, low carbohydrate diet aiming to encourage the body to prioritise using fat as an energy source, subsequently resulting in weight loss, or more specifically, loss of body fat. This is far from the ideal diet for a majority of the general population, let alone an elite athlete or rider impartial to a mid-ride cafe cake stop. Whilst they may sound related, ketone supplementation and the ketone diet are in pursuit of very different goals, despite being founded on similar principles.
Ketones entered the athletic field around the same time, believed to be an additional source of energy for endurance athletes. Some of the most prominent research done at the time was by UK Sport during the 2012 Olympics. This only came to light after the fact, as all athletes on the trial, including Team GB cyclists, were sworn to deny their use and involvement should they fall foul of doping allegations, despite its legality. The rationale based on research was that ketone ingestion would increase ketone levels in the blood, causing the body to shift to using fat as its primary fuel source in lieu of glycogen. Consider a rider coming to the end of a race, having consumed ketones earlier on in the course switching the body’s energy source to fat before their glycogen level entirely depletes. They then have an extra mile in the tank (read: glycogen store) over the last few kilometres to rely upon to get that sprint finish.
Whilst there has been some research and evidence to support this, it is largely anecdotal, with the majority demonstrating no meaningful sign of performance improvement or glycogen preservation. One study implies that ketones do enhance endurance, whereas multiple others go so far as to say performance is negatively impacted due to the side effects and increased lactate levels of participants.
You would be forgiven for questioning why you see so many cyclists at the top of their game immediately turning to it after a race, and top teams signing lucrative sponsorship deals with ketone supplement brands such as Team Visma | Lease A Bike did with Ketone IQ at the start of 2024, when the evidence is so inconsistent. When it comes to the lack of research, that can be attributed to cost. If you’ve ever bought ketone supplements yourself, you will know how eye wateringly expensive they can be, (£45-£70 for three shots alone), so to perform trials and research over a long term period, the cost goes through the roof to a point of unaffordability. The controversy over its legal use continues, when the long term effects of its consumption remains unknown, and current side effects include vomiting and severe gastric distress, not to mention tolerating the foul taste. For these reasons alone, the MPCC has good reason to call for its ban amongst its members. Whilst the UCI advises against its use, they do not outrightly ban it, nor do WADA or the IOC.
As research has continued to progress, the focus has moved from ketones being an additional energy source to a recovery tool. Initial tests have suggested that when taken following intense periods of exercise to a level that has left the glycogen stores depleted, ketones are linked to a higher rate of protein synthesis and glycogen replenishment, accelerating the recovery process. This circumstance particularly highlights their potential appeal amongst the World Tour teams competing in multi-day stage races when riders are emptying the tank on a daily basis.
When it comes down to any rider below the level of the World Tour, professionals across the board including Martijn Redegeld and Iñigo San Millán, don’t advocate their use. Ultimately, there are far greater gains to be made in absolutely nailing your nutrition, rest and training load, without which the potential benefits of ketones would be negligible. We mustn’t forget that the subjects of the scientific trials, as well as those that we see so smoothly knocking back a shot in the tours, are all the upper echelon of elite sport. With the financial and training support of a team and/or sponsorship, a nutrition plan they adhere to, it stands to reason that they could afford ketone use. The high level recreational rider balancing a 9-5 job and salary, perhaps relying on the occasional meal deal, has far greater gains, with a far smaller dent in their bank balance, to be won elsewhere.