Those hoping to ward off weight gain by reaching for a Diet Coke over its sugar-loaded counterpart may, in fact, be achieving the exact opposite effect.   

A new study conducted at Massachusetts General Hospital has found that aspartame – the artificial sweetener found in beverages like Diet Coke – could actually be throwing up roadblocks in your weight loss journey.

“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 Richard Hodin, a surgeon at Massachusetts General Hospital and the study’s senior author.  

The study, which was published in Applied Physiology, Nutrition and Metabolism, found that aspartame inhibits intestinal alkaline phosphatase (IAP), a gut enzyme that scientists believe prevents obesity. What that means is that diet drinks may be preventing, not promoting, weight loss. 

Hoping to observe aspartame’s effects on IAP, the researchers examined four groups of mice over the course of four weeks. Two groups of mice were fed a high-fat diet, with one receiving drinking water containing aspartame and the other receiving plan water. The other two groups were fed normal diets – one with aspartame water and the other with plain water. Those drinking aspartame water consumed the equivalent of three and a half cans of diet soda per day.

“While there was little difference between the weights of the two groups fed a normal diet, mice on a high-fat diet that received aspartame gained more weight than did those on the same diet that received plain water,” wrote the researchers.  

Moreover, the mice who received aspartame water had higher blood pressure as well as higher blood sugar levels, which the researches surmised was evidence of a glucose intolerance.

“Both aspartame-receiving groups had higher levels of the inflammatory protein TNF-alpha in their blood, which suggests the kind of systemic inflammation associated with metabolic syndrome,” reported Science Daily.

“While we can’t rule out other contributing mechanisms,” added Dr. Hodin, “our experiments clearly show that aspartame blocks IAP activity, independent of other effects.”

h/t Gizmodo, Science Daily

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