In the 100-day study, mice that were fed a high-fat diet and given a solution of 50% grapefruit juice throughout the day gained 18% less weight than mice on a high-fat diet that drank water spiked with sweeteners with same caloric content as the juice. Along with gaining less weight, the grapefruit-drinking mice showed a 13-17% reduction in blood glucose levels and 3x lower insulin levels. MORE: The 25 Best Weight Loss Tips Of All Time Pretty cool, right? Researchers credit grapefruit’s blood-sugar lowering effects to the compound naringin—a flavanoid found in the fruit—but the reason for its weight-controlling effects remains a mystery that scientists say they hope to solve. Study author Joseph Napoli says he’s optimistic that the findings of his research will hold true for humans, but at this point, he’s not sure just how much grapefruit or juice we’d need to consume to reap a similar benefit. “Figuring that out is on our to-do list,” he says. Need more reason to embrace this ruby-red breakfast favorite? Grapefruit is packed with immune-boosting vitamins A and C—perfect for staving off the sniffles—and contains a healthy dose of the antioxidant lycopene, which studies suggest may help reduce your risk of certain types of cancer. If you’re on medication, check with your doctor before making this fruit a habit—certain grapefruit compounds can mess with the way your body metabolizes drugs, causing unwanted side effects. These medications include, but aren’t limited to, certain antibiotics, cholesterol-lowering medications, and anxiety medications. MORE: The Best New Diet For Weight Loss Is…
