How many calories are in fingernails?

essentially none, fingernails are made of keratin, which could eventually be digested to yield some amino acids/ proteins. However, no nutritionist would recommend this as the adverse health effects of putting myriads of germs from under fingernails in your mouth and the damage to your tooth enamel (if your preferred method of harvesting is nail biting ) far outweigh this minuscule benefit. Also, I would imagine it tastes much worse than say prime rib.