The grapefruit diet: Is it really healthy?

There's no question that a grapefruit is a healthy food. A serving of this tart, ruby-fleshed citrus has 4 grams of fiber, only 82 calories, and is overflowing with vitamins C and A, and potassium — not to mention antioxidants galore (per US News & World Report). 

So what about the grapefruit diet, an eating plan that's been around since the 1920s and was nicknamed "The Hollywood Diet" when movie actresses began following this plan a few decades later to slim down quickly before shooting a film (per Verywell Fit)? Eh, not so much. Similarly to the cabbage soup diet, the grapefruit diet is an extremely low-calorie diet; one popular version of it requires you to eat only 800 calories a day (per WebMD). People who follow the plan have reported losing as much as 10 pounds less than two weeks, but rapid weight loss is often mainly water weight; plus, it can be associated with weakened bones, a slower metabolism, fatigue, and muscle loss (via Healthline).

"The diet's small portions and limited food options are not sustainable, and grapefruit has a high risk of interacting with many medications and conditions," Kelly Plowe, MS, RD, told Verywell Fit. Consuming grapefruit can cause serious side effects if you are taking certain medications for cholesterol, steroids, anti-anxiety medications, and antihistamines, as well as drugs to prevent rejection of an organ donation, according to the U.S. Food & Drug Administration.

Do grapefruits really contain a fat-burning enzyme?

On the grapefruit diet, you're supposed to eat a breakfast of half a grapefruit with eggs and bacon, and a half a grapefruit plus salad and meat for both lunch and dinner (per Everyday Health). Why all this grapefruit? Because it's supposed to contain a fat-burning enzyme called naringenin (per Shape). Some even have argued that eating a grapefruit burns more calories than it contains (via NDTV). But many experts say it's a myth that there's anything unique about grapefruit. "Grapefruit has no special properties when it comes to weight loss," Elisabetta Politi, RD, nutrition manager of the Duke University's Diet and Fitness Center, told Health. "You lose weight when you expend more calories than you take in."

If you like grapefruit, though — and aren't on any medications that shouldn't be taken with this fruit — by all means, add plenty of it to your diet. "It's a myth that grapefruit is a negative calorie food; No food is," Bonnie Taub-Dix, RDN, told Eat This, Not That! "But, high-in-fiber, low-in-calories, and flavorful still makes it a good addition to a weight loss plan."