Does high-performance keto exist?

Today we’re going to explore whether keto works for athletes. Even if you aren’t a high-performance athlete I believe this is a fascinating topic to learn about, so let’s get to it!

Keto and Endurance Athletes

The ketogenic diet increases fat oxidation, which is the main energy pathway involved in aerobic activity[1].

But does that mean going keto is an automatic win for endurance athletes? Not so fast.

A recent review from the Journal of the International Society of Sports Nutritionfound that current evidence on keto for endurance athletes is inconclusive[1].

While some data do show improvements in body composition and markers of endurance fitness when athletes keto, results don’t always carry over to competition[1][2].

Restricting carbs can work well for lower training intensities, but competing when carb-depleted usually reduces performance in races[3].

The best balance may be to “train low, compete high,” taking into account the correct amount of carbs needed to fuel higher intensity activities[4].

Keto and Strength and Power Athletes 

Unlike endurance athletes, strength and power athletes rely mainly on lower reps and heavy weights to build maximum strength and explosiveness. The main energy pathway for these activities is the short burst ATP-CP pathway, with less reliance on glycolysis (carbs) or fat oxidation.

A 2018 study in the Journal of Strength and Conditioning Research found that for powerlifters and Olympic weightlifters, a low-carb keto diet reduced overall body mass, including lean mass, but did not reduce performance compared to usual diet[5].

That means keto could be a great idea for fat loss or making a weight class — or a terrible idea for strength athletes who are building their foundation or can’t afford to lose muscle mass.

Another study found that after a 3-4 week adjustment period, a keto diet versus a high-carb diet resulted in similar gains in squat and bench press 1 rep max and 5-second peak power production[6]. However, it’s worth noting that sprint performance was significantly lower in the keto group.

Keto and Team Sports

Athletes in most team sports engage in repeated sprint-like efforts, most often with incomplete recovery periods. These activities engage all of the body’s major energy pathways (ATP-CP, glycolytic, and aerobic) with a primary emphasis on glycolytic-lactate metabolism, which relies on carbs[7].

As I mentioned in the previous section, keto may impair sprint ability, although some studies show no decrease[8].

That means team sport athletes should not train or compete in a carb-depleted state for the most part, although there may be individual exceptions to this rule.

American football players and other athletes who need to be heavy and powerful for their sports should approach keto with extreme caution as it will very likely cause unwanted weight loss.

Keto and Combat Athletes

Fighters and other combat athletes usually compete in several 3-5 minute rounds. While these athletes rely heavily on aerobic metabolism, they also frequently tap into glycolytic-lactate and ATP-CP pathways for short intense bursts.

Evidence shows that combat athletes rely on carbs for performance, and cutting carbs tends to decrease competition performance[9].

In most cases, these athletes also have to make weight to compete. Cutting carbs to make weight is an effective strategy that may result in ketosis, but most athletes opt to increase carbs to restore glycogen and add back weight before the fight[9]. That means they’re not in ketosis while competing.

There’s unlikely to be any performance advantage for fighters, boxers, or wrestlers going keto — but increasing blood ketone levels might be beneficial when traumatic brain injuries (TBIs) occur[10]. You don’t necessarily have to go keto, though, as you can also achieve this by taking BHB or MCT oil supplements.

Part two of this series will cover my personal views (I think you’ll be surprised!), plus practical insights for athletes on how and when to use a modified keto diet for optimal results.

Stay tuned, let me know what you think, and I’ll see you soon!


The Science