One cup of grapefruit sections contains 74 calories. Grapefruits are large citrus fruits that range from white to pink to red. They contain a healthy dose of fiber, are low in calories and contain 0 grams of fat.Grapefruits might also help reduce your risk of cardiovascular disease, according to a 2007 article published in the Nutrition Journal..rapefruits are large citrus fruits that range from white to pink to red. They contain a healthy dose of fiber, are low in calories and contain 0 grams of fat.