Ketone Supplements in the Pro Peloton: Science, Hype, and What Amateurs Should Know

Visma-Lease a Bike has a partnership with HVMN. Soudal Quick-Step works with ketone supplement providers. Alpecin-Deceuninck publicly endorses their use. Ketone supplements have become one of the most visible — and most debated — nutritional products in professional cycling.

Then in October 2025, the UCI published its position: "There is no compelling evidence that exogenous ketones enhance athletic performance." They remain legal. They are "not recommended." The ruling satisfied no one.

So where does the science actually stand? And more importantly, if you are an amateur cyclist with a limited budget, is this where your money should go?

How Ketones Work: The Basic Biochemistry

Ketone bodies — primarily beta-hydroxybutyrate (BHB) — are molecules produced by the liver when carbohydrate availability is low. During fasting, starvation, or very low-carb diets, your body ramps up ketone production as an alternative fuel source for the brain and muscles.

Exogenous ketone supplements bypass this process entirely. Instead of producing ketones through dietary restriction, you drink a concentrated ketone ester or salt that rapidly elevates blood BHB levels to 2–5 mmol/L within 30–60 minutes. This creates a state where both glucose and ketones are available simultaneously — something that does not occur naturally.

The theoretical performance benefit is glycogen sparing. If your muscles can use ketones as a partial fuel source during exercise, they burn less glycogen per unit of work. This could extend the time before glycogen depletion — the bonk — and improve performance in ultra-endurance events where glycogen availability is the limiting factor.

What the Research Shows

The Case for Ketones

The most cited positive study comes from Cox et al. (2016), published in Cell Metabolism. Trained cyclists who consumed a ketone ester alongside carbohydrate rode approximately 2% further in a 30-minute time trial following 60 minutes of steady-state exercise compared to carbohydrate alone. The mechanism appeared to be reduced glycolysis and increased fat oxidation during the steady-state phase, preserving glycogen for the time trial.

Some studies have also shown reduced muscle protein breakdown markers after exercise when ketones are consumed, suggesting a potential recovery benefit. Blood leucine concentrations were higher with ketone supplementation, indicating reduced amino acid oxidation during exercise.

The Case Against Ketones

Multiple subsequent studies have failed to replicate the Cox findings. A 2019 meta-analysis in the British Journal of Sports Medicine found no significant performance effect of exogenous ketones across the available literature. Several studies showed a performance decrease with ketone supplementation, potentially due to GI distress, reduced exercise economy, or the metabolic cost of processing ketones alongside carbohydrate.

A key finding: ketone esters can cause significant GI issues. Studies report nausea, stomach cramps, and diarrhea in 20–40% of participants. For a substance marketed as a performance enhancer, a 20–40% chance of GI distress during exercise is a serious practical limitation.

The UCI's 2025 review found that across all published studies, the evidence was inconsistent and the effect sizes, when positive, were small. Their conclusion — "no compelling evidence" — reflected the overall state of the literature.

Where Ketones Might Actually Help

The most plausible use case is ultra-endurance events lasting 4+ hours where glycogen depletion is the primary limiter. In these events, any amount of glycogen sparing could delay the bonk and maintain power output in the final hours. This is exactly why Grand Tour teams use them — a three-week stage race is the ultimate glycogen-depletion challenge.

For efforts under 3 hours, the evidence strongly suggests no benefit. Glycogen stores plus adequate carbohydrate intake (60 –90 g/hr) are sufficient to fuel performance without running into depletion. Ketones are solving a problem that does not exist at these durations.

The Cost Problem

Ketone esters are expensive. A single serving (25–30g of BHB ester) costs $5–$10. For consistent use — pre-ride, during, and for recovery — the monthly cost ranges from $150 to $300. Over a year, that is $1,800–$3,600 for a supplement with ambiguous evidence.

For professional teams with multi-million-dollar budgets, the calculus makes sense. If ketones provide even a 0.5% edge across a Grand Tour, the cost is negligible relative to the prize money, sponsorship value, and performance gains. For a WorldTour team spending $20 million per year, $10,000 in ketones is a rounding error.

For an amateur cyclist spending $200/month on their hobby, $150 in ketone supplements is a massive allocation to a product with uncertain benefits.

What Amateurs Should Spend Money On Instead

Before considering ketones, make sure you have the fundamentals covered. Each of the following has stronger evidence, lower cost, and greater practical impact on performance than exogenous ketones.

Carbohydrate Fueling: The Proven Foundation

The irony of the ketone debate is that the strongest performance intervention during exercise is the exact opposite of ketosis: eating more carbohydrate. Research consistently shows that increasing carbohydrate intake to 90–120 g/hr using dual-transporter formulas (glucose + fructose) improves performance by 5–15% in events lasting over 90 minutes.

The cost is a fraction of ketone supplements. A kilogram of maltodextrin costs $5–$10 and provides 20–30 servings. Even premium commercial drink mixes with optimal glucose-to- fructose ratios cost $1–$3 per serving. You can fuel an entire month of training for less than the cost of a single week of ketone supplementation.

Most amateur cyclists are still drastically under-fueling during rides. If you are consuming less than 60 g of carbohydrate per hour on rides over 90 minutes, fixing your on-bike fueling will produce a far larger performance improvement than any supplement on the market.

Caffeine: The Most Proven Ergogenic Aid

Caffeine at 3–6 mg/kg of body weight, consumed 30–60 minutes before exercise, consistently improves endurance performance by 2–4% across hundreds of studies. It reduces perceived exertion, increases fat oxidation, and improves neuromuscular function.

A cup of coffee costs $0.50. A caffeine pill costs $0.05. Both have stronger evidence of performance benefit than a $7 ketone ester serving.

Sleep: The Free Performance Enhancer

This costs nothing and has a larger effect size than any supplement. Athletes sleeping 7–9 hours show 15–30% improvements in reaction time, a 9% improvement in sprint performance, and significantly better recovery markers compared to those sleeping under 7 hours.

If you are spending $300/month on ketones but sleeping 6 hours a night, you are paying a premium to partially offset the damage caused by not doing the free thing.

The Recovery Angle

One area where ketone supplements may have legitimate value is recovery between stages or multi-day events. Some research suggests that consuming ketones post-exercise reduces muscle protein breakdown, enhances glycogen resynthesis when combined with carbohydrate, and reduces markers of exercise-induced muscle damage.

For Grand Tour riders who race 5–6 hours per day for 21 consecutive days, any improvement in overnight recovery is meaningful. This is likely the primary reason teams continue using ketones despite the ambiguous performance evidence — the recovery benefit in multi-day contexts is a separate (and potentially stronger) use case.

For amateurs who train 5–6 days per week with adequate rest between sessions, the recovery benefit of ketones is unlikely to exceed what proper post-ride nutrition (carbohydrate + protein within 60 minutes, adequate daily protein intake) already provides.

The Bottom Line

Ketone supplements are a marginal-gains product for athletes who have already maximized every other variable. They are the nutritional equivalent of a $10,000 aero wheelset — potentially worth a small percentage gain for someone already at 99% optimization, but absurd as a first purchase.

For the vast majority of amateur cyclists, the hierarchy of spending should be: proper daily nutrition first, on-bike carbohydrate fueling second, quality sleep third, and caffeine fourth. Only after all of these are dialed in — and your budget comfortably allows it — should you consider experimenting with ketones.

And even then, start with a single box to test your individual response. The 20–40% GI distress rate means there is a meaningful chance that the most expensive supplement in your cabinet will make your ride worse, not better.

Eat your carbs. Drink your coffee. Go to bed early. The performance gains hiding in these free and cheap interventions dwarf anything a $7 ketone ester can offer.