Although it’s true that egg whites are low in calories, fat-free, and contain most of the protein found in an egg, eating the entire egg is beneficial to your metabolism. The yolk contains many metabolism-stoking nutrients, including fat-soluble vitamins, essential fatty acids and—most significantly—choline, a powerful compound that attacks the gene mechanism that triggers your body to store fat around your liver. Worried about cholesterol? New studies have found that moderate consumption of two whole eggs per day has no negative effect on a person’s lipid (fat) profile and may actually improve it.