LCHF vs HCLF for athletic performance

Introduction

Many thanks to Jon Furniss for spotting the paper for this week. It features some authors known to us – Professors Tim Noakes, Jeff Volek, and Dominic Agostino. The paper was called “Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males” and it was by Prins et al (Ref 1).

Jon has been a keen and competitive athlete for most of his life, fuelling endurance exercise with large amounts of highly processed sugars and starchy carbs, as most people do. But after developing Type 1 Diabetes at 39, he removed carbs from his diet to help bring his blood glucose back into the normal range. He wondered if he could still perform and compete. He discovered endurance exercise could be mostly fuelled using stored fat, and the way to access this massive energy store was by reducing carb intake to below 50g/day for a few weeks. He did not notice any performance impairment.

This strategy was tested in the ZeroFive100 experiment, where Jon and 7 others ran 100 miles over 5 days without consuming any calories (Ref 2). All eight felt great throughout – both physically and mentally – and they didn’t suffer hunger or any soreness. Jon now does all exercise in the fasted state and reports numerous benefits. He had also read that the wider health benefits of exercise could be offset by an increased cardiovascular risk, such that overall mortality was about the same in serious athletes compared to non-athletes. This caused him to wonder whether the health benefits of exercise might be maintained when fuelling with fat rather than being potentially offset by a carb fuelling strategy. This recent paper appeared to provide evidence for this.