The grapefruit is a citrus fruit related to the orange. The number of calories in one whole grapefruit varies according to its size and type, but overall, this tangy fruit is relatively low in calories. Typically eaten raw and fresh, or juiced, grapefruit boasts several nutritional and health benefits. Although available year round, you'll find grapefruit at its best during the growing season, which is from winter through early spring.
Grapefruits typically range in size from 4 to 6 inches in diameter. Some have seeds, while others are seedless. Grapefruits are available in pink, white and red varieties. The name describes the color of the flesh of the fruit. Another name for red grapefruit is ruby, and white grapefruit is sometimes called blond.
Both pink and red grapefruit are a bit higher in calories than white grapefruit. One whole pink or red grapefruit, raw, has about 104 calories, while one whole white grapefruit, raw, has about 78, according to the USDA National Nutrient Database. These calorie counts are for a medium grapefruit. Larger fruits have a few more calories, and smaller ones have a few less. One cup of fresh grapefruit juice, white or pink, contains 96 calories.
In addition to being low in calories, grapefruit contains valuable nutrients. According to nutrition information listed on the website of the George Mateljan Foundation for the World's Healthiest Foods, grapefruit is an excellent source of vitamin C, which helps fight colds and aids in keeping your immune system healthy. Grapefruit is a good source of vitamin A, folate, potassium, vitamin B5 and dietary fiber. It is also very low in saturated fat and contains no cholesterol.
The George Mateljan Foundation for the World's Healthiest Foods lists nutritional and health benefits of grapefruit. According to the Foundation's website, grapefruit helps lower cholesterol and aids in preventing tumor formation. Drinking grapefruit juice helps protect against colon and lung cancer and reduces the risk of kidney stones.
The National Institutes of Health warns that grapefruit and grapefruit products can interact with certain medications. The interaction can change the effect of the medicine and may possibly cause serious side effects. Consult with your doctor or pharmacist to determine if any of your medications are likely to interact with grapefruit, and if so, you should avoid all grapefruit products while taking those medicines.