The Grapefruit Diet
The Grapefruit Diet also known as the Hollywood Diet, an 18-day diet, dates to 1930 Hollywood.
This so-called fad diet regained popularity in the mid-1970s as a bit of Xeroxlore. It is occasionally attributed (erroneously) to the Mayo Clinic, which has expressed a decidedly negative opinion of the diet, considering it unbalanced and possibly dangerous. However, a 2004 study led by Dr. Ken Fujioka at the Nutrition and Metabolic Research Center at Scripps Clinic found in a 12-week pilot study that on average, participants who ate half a grapefruit with each meal lost 3.6 pounds and those who drank a serving of grapefruit juice three times a day lost 3.3 pounds. Additionally, many patients in the study lost more than 10 pounds.
Dr. Fujioka found that grapefruit diet appears to reduce insulin levels and thus, affects blood sugar regulation. Bear in mind that pancreas secretes insulin in response to the amount of carbohydrate ingested (also affected by the glycemic index and glycemic load of a food or meal) and that grapefruit by itself is considered by some to be low glycemic.
Another theory is that the fruit's low glycemic index is able to help the body's metabolism burn fat.
Still another explanation for the weight loss in the Scripps Clinic study can be found in the report -- participants "slightly enhanced their exercise regimens." Depending upon what "slightly enhanced" means, this might well account for the weight loss observed.
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