Grapefruit for weight loss

In 1930s Hollywood, many stars got onto the “grapefruit diet” which involved having half a grapefruit with meals in the belief that grapefruit contains an enzyme that will burn fat. In the 1970s, the grapefruit diet re-emerged and it has found several incarnations that involved severe kilojoule restriction. There is no doubt that neither woman nor man can live by grapefruit alone but new research has shown that there may be something to that Hollywood practice of the 1930s because grapefruit juice does cause weight loss when on a high fat diet.

For the study, researchers gave mice a high fat diet. Half of the mice were given pulp-free grapefruit juice that was sweetened to make it less bitter. The other mice were given water that was also sweetened so that it had the same sweetness and kilojoule level as the grapefruit juice.

After 100 days, it was found that mice given the grapefruit juice had gained 18 per cent less weight than the mice given the water. The mice given grapefruit juice also showed a 13-17 per cent drop in blood sugar levels and three times lower insulin levels in the blood than the mice given water.

In a follow-up study, one group of mice were given a component of grapefruit juice called naringenin and another group was given metformin, a type 2 diabetes drug. Both groups consumed a high fat diet and naringenin showed the same capacity to lower blood sugar as the metformin. However, neither group showed any reduction in weight gain.

The researchers say that this shows it is not naringenin that has the weight reducing effect but something else in whole grapefruit juice that they have not been able to identify. A caveat to all of this, however, is that grapefruit juice has been shown to alter metabolism of medications so you should not start quaffing grapefruit juice if you are on any medication at all until you consult your health professional. Equally, extreme grapefruit diets that exclude many other foods are not wise either.

All in all, though, it seems that Cary Grant and Mae West were more than stars of the screen, they were dieters ahead of their time. Is there no end to the magic that Hollywood brings?