By 
The low-carb, high-fat ketogenic diet is a controversial one, but many athletes and fitness enthusiasts swear by it and claim that it has had a positive impact on their performance. Curious about the kind of results he might be able to get from achieving ketosis, former professional cyclist Jeremy Powers recently embarked on a 5-hour, 100-mile bike ride while on the keto diet.
He starts out with a breakfast of eggs, bacon, spinach and cheese, then hits the road, maintaining an average speed of 20 miles per hour and keeping a close eye on his heart rate and ketone levels.
"They say when you're working out and you're doing ketosis your ketone levels start to drop, so 0.7 is what I would expect," he says. "I haven't eaten anything yet, I may have a snack.. So far I feel fine, I'm averaging 212 watts, average heart rate of 126."
While on the road Powers eats peanut butter and bacon sandwiches (on keto-friendly bread of course) with salted cashews, as well as using salt capsules to keep up with his body's electrolyte demands considering the day's intense heat.
"I feel a little crampy, I'm not gonna lie, but given the heat and stuff, it's hard to get the electrolytes in," he says. "I feel good overall though, my power output is going up, my ketone level is continuing to rise. So far, so good... I haven't eaten nearly enough calories to justify this type of energy expenditure, but the ketones are protecting me and continuing to churn out, and I'm continuing to be able to do the work, which is so surprising. This is definitely one of the weirdest things I've ever done in my entire life, I can say that factually."
In order to stay safe in the heat, Powers' ride ends up being closer to 90 miles than 100. "I predicted things were going to go a certain way, and the outcomes just didn't come true," he says. "I was certain that I was going to bonk catastrophically and need to be driven home... But literally nothing went wrong. I was able to churn out the watts, my heart rate didn't go crazy, I didn't get heatstroke. I did do the ride at a low intensity, so I didn't give it 100 percent up every climb, but I did have periods where my heart rate went up to 170 and I went super hard."
Powers explains that he has always had a problem with burning out on long races due to his blood sugar, and that this challenge was a way for him to push himself in that regard. "I wanted to see if I could be more metabolically flexible, as a test for myself," he says. "And honestly, this was not easy for me... Diet is so personal. What works for me will not necessarily work for you."
