Real Grapefruit Diet

The real -- or original -- grapefruit diet dates back to the 1930s. It called for eating half a grapefruit with breakfast, lunch and dinner on the premise that the grapefruit would burn away fat from your meals and help you lose weight. Modern versions include several variations. One replaces half a grapefruit with a cup of grapefruit juice, while another involves eating grapefruit and no more than 800 calories a day.

Real Grapefruit Diet Study

Ken Fujioka, a researcher at Scripps Clinic in La Jolla, California, tested the premise of the original -- or real --grapefruit diet of the 1930s. He added grapefruit or grapefruit juice to the diets of obese participants. Participants did not otherwise alter their eating habits, according to the report published in the Spring 2006 edition of "Journal of Medicinal Food." The results gave credence to the premise of the original grapefruit diet.

Results

One third of the participants in Fujioka's grapefruit study followed the exact original grapefruit diet, eating half a grapefruit three times a day before meals. One third followed a slight variation and drank a cup of grapefruit juice before meals, while one third took placebos. After 12 weeks, those who had eaten half a grapefruit before their meals lost an average of 3.6 lbs. Those who drank a cup of grapefruit juice before meals lost an average of 3.3 lbs. The weight loss proved minor -- approximately 1/3 lb. per week -- but would theoretically add up to 17 lbs. of lost weight a year. Participants who took a placebo lost a little more than 1/2 lb. in 12 weeks.

USDA Weight Loss Recommendations

To lose weight in a healthy and effective manner, the United States Department of Agriculture recommends you reduce the number of calories your normally eat by 500 a day. This would mean making changes in your diet other than just adding grapefruit to it. But you could include grapefruit on a reduced-calorie diet -- half a grapefruit contains 41 calories. If you reduced your calorie intake by 500 calories a day and enjoyed the grapefruit fat-burning bonus evidenced in the Scripps Clinic study, you could lose more than 5 lbs. a month.

Drug Interactions

If you take any prescription or over-the-counter medication, consult a doctor before trying the real grapefruit diet -- or any of its variations. Grapefruit can cause dangerous and even fatal side effects when combined with numerous drugs. Grapefruit stops your body's CYP34A enzyme from properly metabolizing medications, creating a potentially lethal excess of medication in your body, according to "The New York Times." Some types of medications known to react negatively with grapefruit include statins, birth control pills, antidepressants, anti-anxiety medications and antihistamines.

Real Grapefruit Diet