Fitness expert and triathlete Ben Greenfield trained for the 2013 Ironman Triathlon World Championships in Kona, Hawaii by following a high-fat, low-carb ketogenic diet and completed the epic endurance race in a blistering 9:59:26.
The Ironman triathlon consists of a 2.4-mile swim followed by a 112-mile bike ride and then a 26.2-mile marathon, without a break.
Greenfield's breakfast the morning of the Ironman was a half-stick of butter, two shots of MCT oil, and a cup of coffee — a stark contrast to the vats of pasta most endurance athletes inhale before a race.
While carb-loading is common in endurance sports, a high-fat, low-carb diet may be better at enhancing athletic performance, Greenfield said on a podcast Oct. 23 with fitness trainer Sam Feltham.
Greenfield also discussed ketosis with Dr. Dominic D’Agostino, who said Navy SEALs follow a ketogenic diet during their underwater training to prevent seizures. Dr. D’Agostino has also done exciting research confirming that a ketogenic diet starves cancer cells to death.
Greenfield joins a growing number of endurance athletes who are sold on the health benefits of a ketogenic diet for endurance training. He previously followed a high-carb diet but switched two years ago after realizing that too many carbs causes inflammation, which can lead to heart disease, Alzheimer's, obesity, and diabetes.
Two years ago, I came across research about pancreatic fatigue and failure, loss of insulin-cell receptor sensivity, and surges in blood glucose leading to inflammation."
After switching to a ketogenic diet, Greenfield experienced improved stamina, stable blood sugar, better sleep, less brain fog, and even better skin and hair. In fact, people are often surprised when he tells them he's a triathlete because he doesn't have the weathered, dried-up look that most endurance athletes have.
Greenfield's observations have been underscored by ground-breaking research from cardiologist Aseem Malhotra, that confirmed that unprocessed saturated fat is good for you and can protect against heart disease, obesity, and diabetes.
Greenfield, a former tennis player and bodybuilder, follows a ketogenic diet year-round because of its positive impact on his overall health.
"I don't change up my diet, even up to the day before a triathlon," said Greenfield. "I eat about 400 calories a day in carbs (or about 100 grams). Or I'll have 150 to 200 grams of carbs on a hard training day. I try to stay in fatty-acid utilization."
Greenfield said his diet typically includes lots of vegetables, moderate amounts of high-quality proteins, and plenty of healthy fats such as coconut oil and MCT (medium-chain triglyceride) oil.
My daily diet includes healthy nutrient-dense fats like wild-caught fish, grass-fed beef, avocados, olives, olive oil, raw almonds, pumpkin seeds, brazil nuts and coconut milk."
While some endurance athletes may be skeptical of the low-carb, high-fat regimen, Greenfield is convinced of its health benefits. In fact, his twin sons follow a high-fat diet, and they are thriving. The five-year-old boys recently completed their sixth triathlon.