Abstract
Six young men were fed a protein-free liquid diet, which was complete in all other nutrients. Consistent and significant hair root morphological changes were evident at 11 days of depletion. These included bulb diameter reduction, atrophy, dyspigmentation, and sheath absence. The growth phase did not change. Urinary nitrogen reached minimum values by 11 days. Total serum protein and albumin levels remained normal. When protein was added to the diet, the hair root changes were reversed.