Ketogenic Diet: Which Patients Benefit?

John Watson; Reviewed by: Anya Romanowski, MS, RD


March 20, 2018

In This Article

Endurance Athletes -- Does KD Enhance Performance?

The benefits of KD are sought not only by patients but also by otherwise healthy athletes looking for a performance advantage.

According to Lorna Doyle, PhD, a lecturer and researcher in nutrition and sports nutrition at Waterford Institute of Technology in Ireland, endurance athletes have moved on from the earlier days of carbo-loading before big events. Aware of the limitations and risks of carbohydrate-heavy diets, many athletes have begun looking for new dietary means of obtaining a performance edge.

Doyle and colleagues studied 20 male endurance-trained athletes (mean age, 33 years) who committed to either a high-carbohydrate diet or KD, while adopting otherwise identical training regimens, for 12 weeks.[29] They found that the KD group had a significantly greater reduction in body mass (-5.9 kg vs -0.8 kg) and body fat percentage (-5.2% vs -0.7%). Although there was no significant difference in athletic performance on the 100-km time trial between the groups, fat oxidation and 6-second sprint power (+0.8 watts/kg) was significantly higher in those on KD.

"I believe that the improvements in body composition were related to the enhanced usage of fat as energy during the 12 weeks; hence, stored body fat was used for energy," said Doyle. "However, the training employed (endurance, strength, and high-intensity interval training) ensured that muscle mass was retained and possibly helped mitochondrial adaptations to enhance fat usage."

For those hoping to follow in the participants' footsteps, Doyle cautioned that such a select diet necessitates its own considerations.

"Focus and attention must be paid to electrolyte consumption to ensure dietary safety. Sodium and magnesium consumption especially is important, particularly for a person exercising. It can be more difficult to get and absorb some electrolytes on a ketogenic diet."

Key Takeaways

To say that we're in the early stages of learning about a treatment that we can trace back to 1921 may sound counterintuitive but is nonetheless true.

Although the impact of KD in epilepsy is unquestionable, and its promise in treating obesity and type 2 diabetes is backed by a growing body of evidence, much of the case for its application in cancer and neurologic disorders relies on early, anecdotal evidence.

If careful not to overstate the case for KD, experts agree that its promise is sufficient to warrant a greater investment in well-designed trials in these areas. A relatively safe intervention that can be administered with a trip to the grocery store, not much can halt this explosion of interest in KD for a wide range of conditions.

Follow Anya Romanowski, MS, RD, on Twitter for more Medscape nutrition news: @Anya13


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