Grapefruit juice has been touted as a weight loss aid since the 1930s, when it gained notoriety as part of the Hollywood Diet. Studies have suggested that a fat-burning enzyme in grapefruit may help you shed pounds, but naysayers say these grapefruit studies are questionable at best. So, University of California, Berkeley researchers set out to validate grapefruit juice’s weight loss abilities. Results confirmed that grapefruit juice can indeed stimulate weight loss, as well as reduce blood glucose levels and improve insulin tolerance…at least in mice.
Enjoy a High-Fat Diet? Just Add Grapefruit Juice!
The study, published in the journal PLOS ONE, examined the effects of grapefruit juice on a high-fat diet. (A high-fat diet, especially when coupled with carbohydrates, has the tendency to promote weight gain.)
Five groups of mice were fed either a high- or low-fat diet for 100 days. To these diets, researchers added clarified, pulp-free grapefruit juice sweetened with saccharine and delivered at different concentrations according to group. The researchers made sure to control for calorie intake, exercise level, and nutrient absorption among the groups, and pitted results against a control group of mice fed a high-fat diet and water sweetened with glucose and artificial sweeteners.
Results confirmed that grapefruit juice may help you lose weight. Mice fed a high-fat diet and water gained 18% more weight than mice fed a high-fat diet and grapefruit juice. The mice on the high-fat/grapefruit juice diet also experienced a 13-17% decrease in blood sugar levels and a 3-fold decrease in insulin levels! And while grapefruit juice did not exert an affect on mice fed a low-fat diet, it did affect insulin levels, reducing them by a factor of two!
But just what compound in grapefruit juice is responsible for the weight loss? Scientists still don’t know. They isolated a compound in grapefruit juice called naringin, which has previously been associated with weight loss. They gave one group of mice fed a high-fat diet naringin and another group also fed a high-fat diet metformin—a drug used to lower blood sugar levels in diabetics. The naringin worked just as well as the prescription drug at lowering blood glucose levels, but had NO effect on weight, suggesting it’s not the naringin that’s causing weight loss, but a mystery enzyme in grapefruit…
Health Benefits of Grapefruit Juice
Sure, human trials need to be conducted to test if grapefruit juice can truly help you lose weight, but since there are no side effects from grapefruit juice, why not conduct your own experiment? Put yourself on a high-fat, low-carb diet and add in some grapefruit juice and see if you shed some pounds! You’ll also benefit from the other health benefits of grapefruit juice, including reduced risk of stroke, lower blood pressure, better heart health, cancer prevention, improved digestion, and radiant skin.