Elite race walkers who eat a super low-carb, high-fat diet for 3 weeks start burning fat like crazy when they exercise — one of the highest fat-burning rates ever seen in top athletes.

Even though elite race walkers get better at using oxygen overall on a keto diet, the diet makes their bodies use more oxygen during race pace, so their performance doesn’t actually improve after 3 weeks.

Elite race walkers who follow a keto diet for 3 weeks start burning fat for fuel during intense exercise, and their bodies show signs of ketosis — like having 1 mmol/L of ketones in the blood — even when working hard.

Elite race walkers who eat lots of carbs or time their carb intake during intense training get about 5-6% faster in a 10 km race, but those on a keto diet don’t get any faster.

Athletes who follow low-carb high-fat diets can burn fat much faster during exercise—over 1.5 grams per minute—compared to athletes on regular high-carb diets who only burn 0.3 to 0.6 grams per minute.

If endurance athletes eat a high-fat, low-carb diet for just 6 days, their bodies burn way more fat during a long bike ride — about 50 grams more over 4 hours — compared to when they eat lots of carbs, even if they're used to carb-heavy diets.