People looking to reduce the amount of calories they consume often switch to artificial sweeteners like aspartame that don’t contain calories like normal sugar.

New research, however, suggests that switch may not be a viable long-term solution for people who are already obese.

This is cause for concern because of obesity’s connection to how the body processes glucose. Obesity and type 2 diabetes share a strong link.

artificial sweeteners and obesity

Jennifer L. Kuk, Ph.D., an obesity researcher in the School of Kinesiology and Health Science at York University Faculty of Health in Toronto, said the research uncovered how obese people who consumed aspartame may have worse glucose management than those who don't eat or drink sugar substitutes.

“Diet sodas aren’t as good as you might hope,” she told Healthline.

Aspartame is one of the most common artificial sweeteners, sold under the brand names NutraSweetand Equal. However, aspartame has been the subject of controversy since its approval in 1981.

Read More: Are Artificial Sweeteners Actually Healthier Than Sugar? »

Artificial Sweeteners’ Effects on Obesity

The study, published last week in the journal Applied Physiology, Nutrition, and Metabolism, concludes the artificial sweetener aspartame may be associated with greater glucose intolerance, a precursor to diabetes.

To reach that conclusion, Kuk and her team used data from the .

Information from 2,856 U.S. adults was used. It included their consumption of the artificial sweeteners aspartame and saccharin, or natural sugars like fructose.

The risk of developing diabetes was measured by an oral glucose tolerance test given at mobile examination centers.

Overall, researchers found that obese people who consumed aspartame — but not saccharin or natural sugars — still had obesity-related deteriorations in glucose tolerance and fasting glucose. These are hallmark signs of metabolic problems that can lead to type 2 diabetes.

In lean people, however, there seemed to be a beneficial effect of consuming aspartame, although researchers noted that so few fit people consume it that the sample size may not be big enough.

This, Kuk says, is a catch-22 because people who eat and drink more sugar tend to be obese, while her research suggests artificial sweeteners that don’t contain calories can also affect how our bodies process sugars.

“Pick your poison, I guess,” she said.

Read More: The Truth About Aspartame Side Effects »

What Happens in the Gut

This could be, in part, because our bodies do not process aspartame in the gut.

Prior studies in mice have shown this effect may be due to how the substance in the gut, which would impact how the body metabolizes what you eat and drink.

Some research has shown aspartame increases total bacteria in the gut while other research suggests some bacteria can break it down, but that they also produce harmful byproducts in the process.

Historically, there’s been little research showing long-term health benefits of low-calorie sweeteners.

Earlier this year, when a U.S. Food and Drug Administration (FDA) panel was reviewing whether to add added sugars to nutritional labels, it was cautious to recommend artificial sweeteners, citing the lack of evidence.

The FDA does call aspartame “one of the most exhaustively studied substances in the human food supply, with more than 100 studies supporting its safety.”

When it comes to deciding whether or not to consume artificial sweeteners, the FDA continues to list them on their Generally Recognized As Safe (GRAS) list.

If you have a sweet tooth, Kuk says, artificial sweeteners are still a good route to go, especially for obese people who are trying to lose weight.

“There’s no strong data to suggest they should be removed from the market,” she said.