Fit with a grapefruit, or not?

Hope to lose weight with grapefruits (Photo: fantasyhealthball)

Hope to lose weight with grapefruits (Photo: fantasyhealthball)

It has long been the belief among some dieters that regularly eating grapefruit can help shed weight. Eat half a grapefruit before each meal and lose 10 pounds in 10 days was the simple mantra. The Grapefruit Diet has actually been along for some 80 years by now. Historically, supporters have claimed that grapefruit contained a fat-burning enzyme or some like compound. For a while it was even called the Hollywood Diet and as we all know many Hollywood stars keep slim forever so it must work. Or not?

There has been much ridicule of such a crazy diet. It has even been satirised in a song with the usual irreverence and mild cruelty of singer “Weird Al” Yankovic. But fad diets will never die — not as long as we live in a world where people seek immediate gratification by following promises to rapidly drop off weight. Or not?

The appeal of instant results perpetuates a growing demand for products or plans assuring overnight success. With more and more people across the globe becoming overweight or obese, fad diets have multiplied. Although fad diets are typically synonymous with dubious science, desperate times require desperate action. Or not?

Unfortunately, quick weight loss is almost always followed by quick regain of weight. That seems to be the inevitable rule. But if we forget the outrageous claims of the proponents of the Grapefruit Diet, might it be some truth behind the claims?

New surprise findings

Well, surprise, surprise, new research from UC Berkeley’s Nutritional Sciences and Toxicology department suggests that the grapefruit diet might actually work, at least to some extent. Previous studies on the potential benefits of the grapefruit diet have been small, not well-controlled, and contradictory.  The new study found that mice fed a high-fat diet gained 18% less weight when they drank grapefruit juice compared with a control group of mice that drank water. Juice-drinking mice also showed up to a 17% decrease in blood glucose levels, and a threefold decrease in insulin levels.

Unbelievable, so to confirm their findings, the researchers repeated the study several times. Each time they randomly divided the mice into six groups, including a control group that drank only water. For the others, clarified, pulp-free grapefruit juice was diluted with water at different concentrations, and sweetened with saccharin to offset grapefruit’s bitterness. Glucose and artificial sweeteners were added to the control group’s water so that it would match the calorie and saccharin content of the grapefruit juice. Half of the groups were fed a high-fat diet and half a low-fat diet. Results confirmed that the mice that ate the high-fat diet and drank diluted grapefruit juice gained less weight than their control counterparts.

Lingering doubts

Still lingering doubts about the power of grapefruits (Photo: Wikimedia)

Still lingering doubts about the power of grapefruits (Photo: Wikimedia)

Now it starts to be a bit confusing. It has previously been proposed that a compound in grapefruit juice called naringin could be the key agent responsible for weight loss. So the researchers replaced the grapefruit juice with this compound. And it had no effect on weight loss but at least reduced blood glucose levels. There is thus a lack of a molecular explanation to their initial findings. Although not a requirement, to be trustworthy it is always good to know why you get certain surprising results.

You should also know that the study was funded by the California Grapefruit Growers Cooperative. Of course the researchers claim that this had no influence on the outcome of the studies. Although I am sure that the researchers acted independently, there are indications that the outcome of externally funded studies often come up with findings pleasing to the funding body. Maybe not in this case, but there is a lingering doubt.

And finally mice and humans that are quite different in their food choice and metabolism might not react the same way to grapefruit juice. Or we may!

Go for it

So what are those caveats to a believer. Go for it if you like as long as you’re careful if on certain medications. There are clear warnings that grapefruit can increase the absorption of some drugs into the bloodstream, creating a potentially dangerous interaction.

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