It is sometimes very surprising to find out who is a sugar-burner and who isn’t. Even professed hard-core endurance sports exponents at the elite level, who have been training over long distances for years, can be big-time sugar-burners.
A man I have advised since 1987, John Meagher, who is now 55 years old, had been one of Australia’s best-performed age-group runners and triathletes for many years, after running a debut marathon of 2hr 16 minutes in 1989, running or cycling high volumes of aerobic training for many years. Earlier this year he explained to me that he often felt tired straight after work (he’s a teacher): he was too tired to run just a few kilometres with the boys he coaches for the school cross-country squad after school. He complained of being light-headed and dizzy on long hilly runs, and not enjoying his long runs any more. He was functioning as a sugar-burner, and possibly was hovering on the edge of insulin resistance, or early type two diabetes. He needed to become fat-adapted again, through diet.
The diagram below perhaps illustrates John’s metabolism when he was a sugar-burning athlete.
I noticed at a few family meals that John ate masses of carbohydrate foods like bread and toast, with the regulation cornflakes for breakfast. If there was salad with lunch or the evening meal, it was minimal, and only a nod in the right direction.
I told him about the fat-adapted diet that Primal Endurance author Mark Sisson advocated, that featured an inclusive spread of as many of the coloured vegetables as possible, often simmered with butter to allow for release of the fat-soluble vitamins A,K, D and E, and minerals like magnesium, in the plant foods. I recommended a regular, filling breakfast with eggs and organic non-nitrite bacon, and left the rest to him.
He also dosed up on a few tablespoons of coconut oil each day; sometimes in a cup of tea. Coconut oil is very rich in medium chain triglycerides which are healthy saturated fats that get quickly converted in the liver to ketones, which are fat-like molecules which are also water-soluble. While the fat-adapted athlete’s muscular system runs off fats by the process of lipolysis, the brain can utilize ketones as a rich fuel source in the absence of dwindling glucose.
Fast forward a few months, and when I last spoke to John, he reported that he was feeling the best he had for years, able to run over 40 kilometres on big hills again, without feeling fatigued. He never had pangs of hunger any more, and his energy levels were always reliable and constant. He is now looking forward to running his best marathon time for several years, without fear of hitting the wall.
John broke the Australian M55+ best marathon time by 11 seconds on October 14th, in the Melbourne marathon, running 2 hours, 37 minutes, and 16 seconds, feeling strong and full of running, with a hard last kilometer in warm, windy conditions.
He recovered very quickly from the marathon, and may attempt to lower his time further in the 2019 Tokyo marathon, on March 3rd.
The diagram below illustrates John’s fat-adapted metabolism now.