Grapefruit has been used to assist in weight reduction since The “Grapefruit Diet” was introduced in 1930 by Kelly D. Brownell, PhD. More recently, studies led by Ken Fujioka, MD of The Nutrition and Metabolic Research Center at Scripps Clinic and Heidi J. Silver, PhD, RD at Vanderbilt University suggest that grapefruit juice can also contribute to weight reduction. When drinking grapefruit juice, you must be careful — grapefruit juice can negatively affect certain medications.
Grapefruit Basics
Grapefruit juice is high in nutrients such as potassium, magnesium, folate and niacin. It is rich in vitamin C. In fact, an 8-ounce glass provides 100 percent of the daily value of vitamin C. Pink grapefruit, which gets its color from carotene, provides vitamin A; white grapefruit does not. According to the Scripps Clinic study, grapefruit and grapefruit juice also contain chemical properties that lower insulin levels.
Insulin Levels
Insulin regulates blood sugar and fat metabolism. High insulin levels increase hunger and thereby promote weight gain. When you eat, insulin levels rise. The smaller the insulin level spike after meals the better your body processes the food for energy. The Scripps Clinic researchers speculated that the insulin level reduction provided by the grapefruit juice is a key factor to promoting weight loss. Lower insulin levels are also beneficial for anyone with diabetes.
Studies
In the study at Scripps Clinic, individuals who drank grapefruit juice lost an average of 3.3 pounds. In this 12 week study, participants drank one glass of grapefruit juice three times per day before meals. Similarly, the 14-week study conducted by Dr Silver at Vanderbilt University showed that participants who drank 4 1/2 ounces of grapefruit juice before the three main meals while on a reduced-calorie diet lost an average of 15 pounds per person.
Safety
Grapefruit juice contains DHB and narningenin, which are believed to interfere with a natural enzyme in the body that breaks down drugs. This interference can negatively impact certain medications such as statins, immunosuppressant drugs, protease inhibitors, antihistamines, high blood pressure medication and anti-anxiety drugs. If you have an underlying medical condition and take prescription medication, you'll want to check with your health care provider or pharmacist before starting a diet containing grapefruit juice.
References
- Medical News Today; Grapefruit and Weight Loss; Jan 24 2004
- PR Newswire; New Research Suggests Grapefruit Can Play a Role in Weight Loss Success; April 27 2011
- University of Florida IFAS Extension; Using Medications Safely: Interactions Between Grapefruit Juice and Prescription Drugs; R. Elaine Turner and Gail C.; Feb 6 2002
- Consumer Health Information Corporation; Grapefruit Juice – Is It Always Healthy?; Meggan Weisberg
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