Grapefruit has a long-standing reputation as a diet food -- it's even the basis of fad diets such as the grapefruit diet. And while grapefruit juice has some potential weight loss benefits -- and contains nutrients that might support weight loss -- it's not a guaranteed weight loss cure that will compensate for a poor diet or a sedentary lifestyle. Include grapefruit juice in a sustainable, balanced diet for the greatest weight loss benefits -- don't look to it as a cure-all for body fat.
Check with your doctor before adding grapefruit or grapefruit juice to your diet -- it can interact with certain medications, so your physician can let you know if it's safe for you.
Calories and Grapefruit Juice
Managing your calorie intake should be your top priority when you're trying to shed belly fat -- if you're not consuming fewer calories than you burn, you won't lose weight. Lower your calorie intake to 500 fewer calories than you burn daily to lose 1 pound weekly, or go for more aggressive weight loss with a 1,000-calorie deficit for 2 pounds of weight loss each week. Make sure you're meeting your minimum calorie needs, though -- 1,800 and 1,200 calories for men and women, respectively -- or you'll slow your metabolism and stall weight loss.
As a moderate-calorie food, unsweetened grapefruit juice can fit into a weight-loss diet. One cup of pink or white grapefruit juice has roughly 95 calories -- that's about 5 percent of your calorie budget if you eat 1,800 calories daily for weight loss, or 8 percent if you eat 1,200 calories. Just make sure to count the calories in grapefruit juice as part of your daily intake, and measure your portion size before drinking to avoid taking in too many calories -- a bottle of grapefruit juice, for example, might contain more than one serving of juice.
The Evidence for Grapefruit Juice and Fat-Burning
There is some preliminary -- and conflicting -- evidence about grapefruit juice and belly fat. Mice fed grapefruit juice gained less weight than mice that didn't get grapefruit juice -- even though both groups followed a diet designed to trigger weight gain, reports a study published in PLoS One in 2014. And a human study, published in the Journal of Medicinal Food in 2006, found that obese study subjects who drank grapefruit juice, ate grapefruit or took a grapefruit extract supplement lost more weight over the 12-week study period than study subjects who didn't get grapefruit.
However, a more recent human study, published in Metabolism in 2012, found that healthy people who ate grapefruit as part of a nutritious diet didn't lose any more weight than people who just ate healthfully, without a particular focus on grapefruit. These conflicting results mean that grapefruit might not have a significant effect on weight loss for everyone or that it might not offer added health benefits if you're already eating a healthy diet. Larger, long-term studies are still needed to know if grapefruit truly aids in fat loss.
Other Potential Health Benefits
While the jury is still out on whether grapefruit can directly reduce body fat, it does offer beneficial vitamin C -- a nutrient you'll want in your diet for fat loss. Vitamin C plays a role in enzyme function in your cells, and low vitamin C levels can make it harder to oxidize fat during exercise, according to a Nutrition and Metabolism study published in 2006. The researchers compared the fat burn in people who had lower-than-optimal vitamin C levels with those who had healthy vitamin C levels, and found that not getting enough vitamin C hinders fat burning during exercise. Since a cup of unsweetened grapefruit juice supplies all the vitamin C you need for the day, it can protect you from low vitamin C levels.
Drinking grapefruit juice might also help with weight control if it boosts your overall juice intake. A five-year study published in the Journal of the American College of Nutrition in 2010, found that people who drink 100-percent fruit juice tend to be leaner and less likely to suffer from obesity than those who don't.
Avoid Juice Cocktails and Try Whole Grapefruit
Get the greatest number of fat-burning benefits by choosing 100-percent grapefruit juice that doesn't contain any added sugar. Sweetened grapefruit juice is higher in calories than unsweetened juice -- 115 calories per cup, compared to 95 calories -- and drinking sugary drinks is strongly linked to obesity, explains the Harvard School of Public Health. Check the nutrition label to make sure you're getting pure juice, not a sugary juice cocktail.
While grapefruit juice has some potential benefits, you might notice more fat-burning effects from eating whole grapefruit. Juicing removes most of the fiber from the fruit, but fiber actually helps you lose weight by helping you feel full after you eat. A cup of grapefruit juice has a negligible 1 percent of the daily value for fiber, compared to 10 to 12 percent in a medium white or pink grapefruit, respectively.