ISLAMABAD: However, new research suggests the sweetener may be ineffective for weight loss, and it may even have the opposite effect.

Aspartame is a common sugar substitute used as a sweetener in many prepared foods and beverages, particularly diet soda. It is a common choice for those trying to lose weight, as it lowers the number of calories in food.

Dr. Hodin and team had conducted previous research where they fed IAP to mice that were on a high-fat diet. They found that IAP can prevent the onset of metabolic syndrome, as well as reduce the symptoms in animals that already had the condition.
Based on this known relationship between IAP, phenylalanine, and aspartame, researchers hypothesized that consuming aspartame may promote metabolic syndrome because of its inhibition of phenylalanine.

Dr. Hodin and team found that IAP activity was reduced when it was added to a drink containing aspartame, but IAP levels remained the same when IAP was added to a drink containing sugar. "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," says Dr. Hodin.

Inside the human body, aspartame is metabolized and broken down into phenylalanine, aspartic acid, and methanol. Phenylalanine and aspartic acid are amino acids that are naturally present in many protein-containing foods.

However, phenylalanine inhibits the production of IAP.

Dr. Richard Hodin
"We think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP. 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."

While the researchers admit that other contributing factors may play a role, Dr. Hodin emphasizes that the findings "clearly show that aspartame blocks IAP activity, independent of other effects."