No, grapefruit is not a calorie-free fruit, as some diets would have you believe. Despite its reputation as a "fat-burner," grapefruit has no special ability to burn away excess fat. But it is low in calories, and its soluble fiber content is decent enough to fill you up, discouraging you from overeating.
So yes, grapefruit can help you lose weight, just not as easily as some would say. And it's nutritious, to boot. Grapefruit is a tart-tasting fruit not everyone enjoys. But for those who do, grapefruit offers a lot of nutrition for few calories.
Grapefruit is an excellent source of vitamin C. Pink and red grapefruit are good sources of disease-fighting beta-carotene. If you peel and eat a grapefruit like you would an orange, you get a good dose of cholesterol-lowering pectin from the membranes -- the same soluble fiber that fills you up by dissolving in water and creating gels. As a member of the citrus family, grapefruit is also a storehouse of powerful phytochemicals such as flavonoids, terpenes, and limonoids. These naturally occurring substances may have cancer-preventing properties.
Pink grapefruit contain a carotenoid called lycopene. Lycopene helps protect cell membranes and may suppress tumor growth, especially prostate tumors.