The second leanest steak, also known as a London Broil or Family Steak, is the Lean Top Round Steak, which contains 240 calories, 7.6 grams of fat, and 36.9 grams of protein in a 3.5-ounce serving. This cut is taken from the cow's rump, which produces most of the animal's motions and, by nature, has little fat.