The Internets are alive with the bleats of blogs (including ours) beating the anti-artificial sweetener drum, specifically against those ensconced in soft drinks. A bunch of big studies published over the past few decades have shown that switching from full-sugar sodas to diet sodas may not be the best way to limit the negative nutritional effects of these tasty drinks. Most of them have found that, for some reason, the fake sugar substitutes are messing with the body's metabolism and causing weight gain.

New research presented at the recent Endocrine Society’s 99th annual meeting in Florida may now shine more light on what is exactly happening when we down lots of artificial sugar. For the study, scientists tested sucralose (one of the most popular artificial sweeteners used in diet soda) on stem cells that were put in Petri dishes with a base that promotes fat production. After 12 days they found more genes expressing markers for fat creation and inflammation, plus they noticed more fat droplets in the cells themselves, indicating they may contribute to metabolic dysfunction.

For the next part of the study, researchers harvested some fat samples from people who reported that they often consumed low-calorie sweeteners, with half of the subjects at a healthy weight and the other half obese. Similar to the Petri dish experiment, they found increased expression of genes linked to making fat, and more evidence of sugar transportation into cells. And they were able to show that since artificial sweeteners are usually many times sweeter than sugar, consumption can cause an overexpression of sweet taste receptors in fat cells, which they speculate may facilitate the entrance of more sugar into cells and, hence, the blood.

From our study, we believe that low-calorie sweeteners promote additional fat formation by allowing more glucose to enter the cells, and promote inflammation, which may be more detrimental in obese individuals,” said Sabyasachi Sen, M.D., an associate professor of medicine and endocrinology at George Washington University.