In 1864, they climbed Mt. Faulhorn in the Swiss Alps. Prior to the climb, they eliminated protein from their diet, reasoning that nonprotein nutrients would have to supply them energy. McArdle, William D.; Katch, Frank I.; Katch, Victor L. (2014-05-01). Exercise Physiology: Nutrition, Energy, and Human Performance (Page xxxii). LWW. Kindle Edition.