A half of a medium pink grapefruit contains about 40 calories, making it one of the lowest-calorie fruits you can eat. A whole medium pink grapefruit comes in around 80 calories. That’s roughly half the calories of a medium banana and fewer than a medium apple.
Calories by Serving Size
The standard serving size for grapefruit is one half of a medium fruit, which weighs about 120 grams (a little over 4 ounces of edible flesh). At 40 calories per half, here’s how the numbers scale:
- Half a medium pink grapefruit (120g): 40 calories
- One whole medium pink grapefruit (about 4 inches across): ~80 calories
- One large pink grapefruit (about 4.5 inches across): ~100 calories
- 8 ounces of 100% pink grapefruit juice: 94 calories
The juice is notably more calorie-dense than the whole fruit. An 8-ounce glass contains 19 grams of natural sugar compared to roughly 9 grams in an entire medium grapefruit. You also lose most of the fiber when you drink juice instead of eating the fruit.
Full Nutrition Breakdown
Pink grapefruit is mostly water, which explains the low calorie count. But it packs a surprising amount of nutrition into those 40 calories per half. A whole medium pink grapefruit gives you about 9 grams of natural sugar and 1.4 grams of dietary fiber. Fat and protein are negligible.
Where pink grapefruit really stands out is its vitamin content. A large pink grapefruit delivers about 57 milligrams of vitamin C, which covers most of an adult’s daily needs. It also provides a solid dose of vitamin A, thanks to the same pigments that give the flesh its pink and red color. Those pigments include lycopene, the same antioxidant found in tomatoes. A large pink grapefruit contains roughly 1,884 micrograms of lycopene.
Pink vs. White Grapefruit
Calorie-wise, pink and white grapefruit are nearly identical. The real difference is in their micronutrients. Pink and red varieties contain significantly more vitamin A and lycopene than white grapefruit, which has almost none of either. If you’re choosing between the two purely for nutrition, pink wins. If you prefer the slightly sharper, more tart flavor of white grapefruit, you’re not sacrificing much in terms of calories or vitamin C.
Grapefruit and Weight Loss
Grapefruit has a long-standing reputation as a “fat-burning” food, but clinical research doesn’t support that claim. A randomized controlled trial gave 74 overweight adults either half a fresh pink grapefruit with each meal (three times daily) or a control diet for six weeks. The grapefruit group did not lose significantly more weight than the control group. Earlier studies that showed weight loss of 1.6 to 5.8 kilograms were likely seeing the effects of the low-calorie diets participants followed, not the grapefruit itself. Grapefruit has no thermogenic properties, meaning it doesn’t boost your metabolism or help you burn extra calories.
That said, grapefruit is still a smart choice if you’re watching your calorie intake. At 40 calories per half, it’s a filling snack with enough fiber and water content to take the edge off hunger. The grapefruit group in that same trial did see a significant reduction in waist circumference (about 2.5 centimeters), even without overall weight loss. It’s a useful fruit in a calorie-controlled diet. It’s just not magic.
A Note on Medication Interactions
Pink grapefruit contains compounds that block a specific enzyme your body uses to break down many common medications. This can cause the drug to build up to higher levels in your bloodstream than intended, sometimes dangerously so. The interaction affects a wide range of prescriptions, including certain cholesterol-lowering drugs, blood pressure medications, and anti-anxiety medications. If you take any prescription medication regularly, check the label or ask your pharmacist whether grapefruit is safe to eat alongside it. Even a single serving can trigger the interaction, and the effect can last for over 24 hours.