For years, grapefruit diet fans swore that the fruit, if eaten before other foods, contained enzymes that burned off fat. Some claimed the grapefruit combined with calorie reduction resulted in losses of 10 pounds in 10 days. While the fat-burning claims have not been proven, there have been studies that supported the weight loss claim. One theory was that the grapefruit made the eater feel fuller so they wound up eating less. It was also consumed with cups of water, which also probably helps reduce hunger.
A new study from the University of California, Berkeley, however, suggests that drinking the grapefruit in juice form instead of water could be the key to the diet and dealing with diabetes. Published in PLOS ONE, the research found that mice that drank sweetened grapefruit juice instead of water gained less weight on a high-fat diet than mice that drank sweetened water. The juice-drinking mice also had better metabolic health measures, including their blood sugar levels. It also affected their insulin sensitivity, which can be important in protecting against diabetes.
For the study, mice were divided into six groups, including a control group that solely drank water. The grapefruit juice was sweetened to combat problems with previous studies where the mice given juice slimmed down more than those that drank water, but was possibly because mice do not like grapefruit juice. So, in this study, the taste was doctored with artificial sweeteners. Furthermore, the researchers added glucose and artificial sweeteners to the control group’s water so it matched the saccharin content and calories consumed by the grapefruit juice drinking mice.
For 100 days, some of the mice were fed a diet that was 60 percent fat, while others consumed a diet that was 10 percent fat diet for 10 days. The groups of mice drank similar amounts of grapefruit juice and water. They also ate similar amounts of food.
The study found that the mice fed the high-fat diet gained 18 percent less weight when they drank no-pulp grapefruit juice than the mice that ate the high-fat diet and drank water. The researchers found that the mice that drank grapefruit juice also had a decrease of 13 to 17 percent in their blood glucose levels and a noticeable decrease in their insulin levels.
In another experiment, the research team allowed the mice to become obese before they introduced the grapefruit juice. They found that the mice that were given the grapefruit juice wound up weighing 8 percent less than the mice that were given water.
Most fad diets have not had the lasting power as the grapefruit diet. But, the studies show that grapefruit juice is effective in helping a diet and helping against diabetes.