Many people ditch sugary fizzy drinks in favour of low-calorie alternatives when they are trying to lose weight, but a study has found that diet drinks could actually make it harder to shift the pounds.
Many diet drinks contain the sweetener aspartame in lieu of sugar, and researchers at Massachusetts General Hospital have found that mice who were given aspartame in their drinking water gained more weight than those on a similar diet, but without the sweetener.
"Sugar substitutes like aspartame are designed to promote weight loss and decrease the incidence of metabolic syndrome, but a number of clinical and epidemiologic studies have suggested that these products don't work very well and may actually make things worse," said Dr Richard Hodin, lead author of the study, which was published in the journal Applied Physiology, Nutrition and Metabolism.
"We found that aspartame blocks a gut enzyme called intestinal alkaline phosphatase (IAP) that we previously showed can prevent obesity, diabetes and metabolic syndrome; so we think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP."
Researchers studied four groups of mice for 18 weeks. Two groups were given a normal diet, one receiving plain water, the other water with aspartame. The other two groups were given a high-fat diet, with the same water varieties.
Among the groups fed a normal diet there was little difference in weight at the end of the study period. However, those on a high-fat diet given aspartame were shown to gain more weight than those receiving plain water.
"People do not really understand why these artificial sweeteners don't work. There has been some evidence that they actually can make you more hungry and may be associated with increased calorie consumption. Our findings regarding aspartame's inhibition of IAP may help explain why the use of aspartame is counterproductive," said Hodin.
"While we can't rule out other contributing mechanisms, our experiments clearly show that aspartame blocks IAP activity, independent of other effects."
Source : http://www.telegraph.co.uk/