Matt Fitzgerald is an acclaimed endurance sports and nutrition writer and a certified sports nutritionist. He is the bestselling author of more than a dozen books on running and fitness, including 80/20 Running, Brain Training for Runners, Racing Weight, and Iron War, which was long-listed for the 2012 William Hill Sports Book of the Year. He is a columnist on Competitor.com and Active.com, and has contributed to Bicycling, Men's Health, Triathlete, Men's Journal, Outside, Runner's World, Shape, and Women's Health. He lives in San Diego, California.

Tim Noakes, MD, is a South African scientist known for challenging common paradigms of exercise physiology. He espouses the controversial low-carbohydrate, high-fat diet, sometimes called LCHF or even "Tim Noakes." In the early 1990s he cofounded the Sports Science Institute of South Africa. Since 1996, his physiological research has produced more than 370 scientific articles. Noakes took on the sports drink industry with his studies of hyponatremia, and was awarded the International Cannes Grand Prix Award for Research in Medicine and Water on that front. In 2005 he undertook a series of pioneering experiments in the Arctic and Antarctic to understand the full range of human capability in extreme cold, and coined the phrase "anticipatory thermogenesis" in the process.