NASHVILLE, Tenn. -- The Grapefruit Diet was a popular fad in the 1960s and 1970s.

Eating the fruit or drinking the juice before every meal was said to speed up metabolism and burn away fat.

There was little evidence to support or dispel those beliefs back then, but dieticians are now having different thoughts.

A grapefruit study at Vanderbilt Medical Center has already shown some enouraging weight loss results.

In five months, grapefruit study participant Kelly Willenburg has gone from a size 18 to a size 10, and she said she has more energy and willpower than ever before.

"Since June 1, when I started the grapefruit study, I'm down 26 pounds. It’s still coming off and I'm still very excited,” said Willenburg.

"I’ve been the perpetual dieter, everything from Atkins to Weight Watchers. This is the first time I've ever lost it consistently and feel good while I was dieting and I don't feel hungry."

"We are getting feedback from our study subjects that it's helping them eat less and helping them stay motivated to lose weight," said research director Heidi Silver.

Some study participants drink the juice, while others like Willenburg eat the whole fruit.

"If you're eating the whole fruit, you're getting more fiber in your diet. By doing it this way, you're able to eat the entire fruit. You get all the fiber, you get all the juice. (It has) all the components that might offer health benefits,” said Silver.

Grapefruit is certainly more portable this way.

"I bring grapefruit with me to have for lunch. Every night before I have dinner, I take grapefruit in my purse. I have grapefruit in my car," said Willenburg.

“I’m a grapefruit addict, I think. The grapefruit diet has changed my life."

Grapefruit has only about 84 calories per serving.

But beyond weight loss benefits, the study is looking at increased energy, higher metabolic rate, decreased appetite and lower cholesterol levels as a result of adding grapefruit to a healthy diet.

Grapefruit does negatively interact with some medications, so anyone wanting to add grapefruit to their diet should first talk to their doctor.

Vanderbilt has 60 people enrolled in the study. Their goal is to have 90 participants.

If you are 21-50 years old and interested in signing up for the study, call 936-0985.