Stilly, my fingernails have always been brittle, and my skin dry to the point of damage. The keto diet has definitely improved my skin, which is far less itchy than it has been in years, but I don’t see any change in finger- or toenails. I assume this is because nails grow very slowly compared to skin, and are “dead” material. I believe the skin improvement can best be attributed to the high fat content of keto (rather than its protein content), and to the anti-inflammatory effect of its low carbohydrate content.