The rumor that grapefruit can seemingly melt away unwanted fat is a long-standing one. In fact, some manufacturers add it to their weight-loss products with claims that you can lose weight fast with little effort. Unfortunately, scientists have yet to discover a magic bullet that will blast away the pounds. The age-old advice of exercise and a healthy diet still stands when it comes to weight loss. However, grapefruit appears to increase weight loss in a specific group of people.
University of Arizona researchers examined the effects of grapefruit consumption on the body weight of healthy, overweight adults. Participants consumed half a grapefruit three times a day with each meal for six weeks. A control group consumed a low-calorie diet for the six weeks. Researchers found that the grapefruit group lost only a modest amount of weight. They concluded that grapefruit consumption fails to result in significant weight loss. The results were published in the July 2012 issue of the journal "Metabolism."
An earlier study, published in the March 2006 issue of the "Journal of Medicinal Food," found that certain people benefit from grapefruit. In the study, people with insulin resistance who consumed half a grapefruit before each meal experienced significant weight loss. The exact mechanisms are unknown, but the authors speculate that grapefruit's beneficial effect on insulin resistance aided in weight loss. Insulin resistance occurs when your body becomes insensitive to the effects of insulin, which is a hormone that regulates blood glucose and is involved in fat storage.
Unless you are resistant to insulin, grapefruit is unlikely to cause a change in your weight. However, grapefruit is rich in antioxidants, vitamins C and minerals. In addition, both studies concluded that grapefruit exerts a favorable effect on cholesterol and blood pressure. Consuming grapefruit daily for six weeks reduced low-density lipoprotein -- a harmful form of cholesterol -- by 11 milligrams per deciliter, according to the study in "Metabolism." It also reduced systolic blood pressure -- the force against your arteries when your heart pumps -- by three points.
Grapefruit and other citrus fruit can interact with certain medications. Substances in grapefruit interfere with enzymes in your liver that break down a variety of medications. When this occurs, the circulating medication can rise to dangerous levels and causes serious side effects. The list of drugs that interact with grapefruit includes anti-anxiety, anti-depressant, anti-seizure, statin and antihistamine medications. Consult your physician for a full list and avoid grapefruit if you are taking any of these medications.
- Metabolism: The Effects of Daily Consumption of Grapefruit on Body Weight, Lipids, and Blood Pressure in Healthy, Overweight Adults
- Journal of Medicinal Food: The Effects of Grapefruit on Weight and Insulin Resistance: Relationship to the Metabolic Syndrome
- MayoClinic.com: I Like to Drink Grapefruit Juice but Hear That It Can Interfere with Some of My Prescription Medications. is That True?
Janet Renee is a clinical dietitian with a special interest in weight management, sports dietetics, medical nutrition therapy and diet trends. She earned her Master of Science in nutrition from the University of Chicago and has contributed to health and wellness magazines, including Prevention, Self, Shape and Cooking Light.