A new study shows that grapefruit juice taken right after meals could significantly help in weight loss*, but FDA warns it can affect medications metabolism.
The UC Berkeley researchers realized that mice that drank sweetened grape fruit juice didn’t gain much weight after despite of being under high-fat diet compared to their counterparts who only took sweetened water. The mice that consumed the juice also showed better metabolic health such as levels of blood sugar and sensitivity to insulin.
For mice eating low-fat diet, the grape juice didn’t affect loss or gain in weight, according to the researchers. However, it made their bodies more sensitive to insulin.
These finding were published on Wednesday by the Journal PLOS ONE
Findings from the study come with a number of warnings. In the first place, the research was funded by California Grape Growers Cooperative. However, Berkeley researchers claimed that they went on with study from the University’s Department of Nutritional Sciences and Toxicology with a lot of uncertainty about the dietary power of grapefruits.
Andreas Stahl, the study’s senior author, in a statement said he was surprised by the findings, adding that even after rechecking calibration of their glucose sensors, they continued getting the same results.
Another caveat about the study is that it was very small, only involved 6 mice per group assigned a combination of diet liquid and other nutrients.
Finally, not all that happens in mice happens in human.
However, the results could be helpful in giving enough reasons why most fad diets usually contain grapefruits.
Mice aren’t bothered by the bitter taste of grapefruit juice, derived from a flavonoid known as naringin. Previous studies of mice that shed weight after they were given grapefruit juice instead of water, suggested that perhaps the bitterness made them to lose* appetites.
The Berkeley hoped they would solve this mystery using two things. They began by sweetening the pulp-free grapefruit juice (obtained from California Ruby Red grapefruits) using saccharin. Next, they gave mice in the control group sugar water made with glucose and saccharin containing similar amount of calories as the sweetened juice.
Mice that were offered grapefruit juice and water consumed the same amount. Still, they ate similar amounts of food.
After being fed with high-fat foodstuff for 100 days, the mice fed in grapefruit had lost weight by 18.4% compared to their counterparts who took sweetened water. The changes in weight became noticeable after only 15 days in to the experiment while gap was statistically significant on the 78th day.
The mice on grapefruit juice also showed better metabolic healthy after the 100 days compared to the group that took the same calories as sugar water. They exhibited lower fasting glucose, better insulin sensitivity and lower levels of triglycerides in their livers.
The researchers went ahead with follow up experiments, letting the mouse to become obese ahead of introducing the grapefruit juice. After 55 days the mice that took sugar water were 8% heavier than those who relied on grapefruit juice.
Then researchers went on to compare the effects of grapefruit juice with grapefruit flavonoid naringin and diabetes drug metformin. These treatments caused a reduction* blood sugar in mice compared to mice that relied on juice. However, the mice on the juice group showed significant reduction* in weight in day 106 by weighing 14% less than mice in other groups.
Though it is not clear how grapefruit juice helps in weight loss*, more so with the active ingredient naringin, the study proved same effects. But the researchers said that mice on the juice group showed a reduction* of a protein responsible for regulating metabolism, and therefore something in grapefruits perhaps changes how the body makes or stores fats.
The researchers warned that grapefruit and grapefruit juice can affect how a person’s body ability in metabolizing some drugs. These include drugs for controlling cholesterol, blood pressure, heart arrhythmia, anxiety, and allergies, in reference to the Food and Drug Administration. In a video, the FDA said that scientists are trying to come up with a hybrid grapefruit that can be used safely with medication.