Grapefruit Juice Prevents Weight Gain with a High-Fat Diet

Want to lose some weight? You may want to try some grapefruit juice. Scientists have found that mice fed a high-fat diet gained 18 percent less weight when they drank clarified, no-pulp grapefruit juice compared with a control group of mice that drank water.

"I was surprised by the findings," said Andreas Stahl, one of the researchers, in a news release. "We even re-checked the calibration of our glucose sensors, and we got the same results over and over again."

The researchers randomly divided mice into six groups, including a control group that drank only water. Those drinking grapefruit juice got a mixture diluted with water at different concentrations, and sweetened slightly with saccharin to counteract the grapefruits bitterness. The scientists also added glucose and artificial sweeteners to the control group's water so that it would match the calorie and saccharin content of the juice.

In the end, the researchers found that the mice that ate the high-fat diet and drank diluted grapefruit juice gained less weight and even had a 13 to 17 percent decrease in blood glucose levels. They also had a threefold decrease in insulin levels.

"The grapefruit juice lowered blood glucose levels to the same degree as metformin," said Joseph Napoli, one of the researchers. "That means a natural fruit drink lowered glucose levels as effectively as a prescription drug."

Currently, the researchers aren't sure which active compounds in grapefruit juice could be causing the weight loss. However, it's obvious that grapefruit juice does warrant further study. While there wasn't as big as an impact on mice that ate a low-fat diet, there was still a decrease in insulin levels. Needless to say, grapefruit juice should be studied further.

"Basically, we couldn't see a smoking gun that could explain why or how grapefruit juice affects weight gain," said Stahl. "Obesity and insulin resistance are such huge problems in our society. These data provide impetus to carry out more studies."

The findings are published in the journal PLOS One.