Researchers say the sugar substitutes may hinder metabolism, leading to quicker fat production in some people’s bodies.

As more Americans turn to artificial sweeteners to reduce their sugar consumption, scientists are beginning to explore how the substitutes react in the body.

A study unveiled last week concluded that some artificial sweeteners may hinder our metabolism, rather than ramp it up.

This is particularly true in people who are already obese.

In the new study, researchers tested how sucralose reacted in human stem cells that can change into fat, muscle, bone, or cartilage cells.

Scientists placed sucralose-saturated cells in petri dishes with substances that promote fat production.

After 12 days, the cells — which held the amount of artificial sweetener equal to about four cans of soda — showed an increase in fat production from these genes.

Read more: Artificial sweeteners may not be sweet to obese people »

The study’s principal author is Dr. Sabyasachi Sen, an associate professor of medicine and endocrinology at George Washington University in Washington, D.C.

Once the results from the petri dish were tallied, Sen and his researchers conducted further assessments.

They analyzed samples of abdominal fat from eight people who said they consumed artificial sweeteners, mostly sucralose, traces of aspartame, or acesulfame potassium.

Half of the samples came from people who were at a healthy weight while the other half came from people considered obese.

According to Sen, researchers saw evidence of increased glucose in abdomen fat cells and ramped up fat-producing genes in those who were obese.

Other people who didn’t consume artificial sweeteners didn’t produce the same results.

The report also revealed that people who consumed low-calorie sweeteners — which can be seven times sweeter than regular sugar — showed an “overexpression” of sweet taste receptors in their fat cells.

That rate was almost three times higher in people with a history of artificial sweetener consumption than compared with people who didn’t consume the sugar substitute.

“Many health-conscious individuals like to consume low-calorie sweeteners as an alternative to sugar. However, there is increasing scientific evidence that these sweeteners promote metabolic dysfunction,” Sen said in a press release.

The findings appear to run contrary to what many Americans believe, according to Dana Hunnes, PhD, MPH, RD, senior dietitian and adjunct assistant professor in the Fielding School of Public Health at the Ronald Reagan University of California Los Angeles (UCLA) Medical Center.

Consuming artificial sweeteners in place of real sugar can help some people lose weight, but it may have a hidden downside.

“I don’t think we really yet know the extent of what artificial sweeteners are doing to our bodies,” Hunnes told Healthline.

Read more: Is diet soda safe for people with diabetes? »

More Americans are using artificial sweeteners than ever before.

A study published earlier this year revealed that artificial sugar consumption among adults is up by 54 percent. In children, it’s up by 200 percent.

Health experts say the reason is because artificial sweeteners can be found in products that line grocery store aisles — from beverages, to popcorn, and even English muffins.

Food labels that use the words “light” or “reduced sugar” often carry some type of artificial sweeteners.

“It’s everywhere,” Hunnes said.

There are currently about seven types of artificial sweeteners on the market.

Sucralose is considered one of the most popular. When the product was first introduced, it was marketed as a safe alternative, according to Hunnes, because it’s made from sugar.

In recent years, food companies have added artificial sweeteners to their products as a way to provide low-calorie foods without sacrificing taste. And people are gobbling it up, according to Hunnes, because “people think it’s safe.”

Read more: America’s deadly sugar addiction »

Sen’s research, although utilizing a small sample size, is telling, according to Hunnes.

It supports the hypothesis that increased consumption of artificial sweeteners may lead to weight gain and diabetes, as other studies have pointed out.

A 2013 study showed an increased risk in type 2 diabetes in people who consume diet beverages that had artificial sweeteners in their ingredients’ lists.

However, further experiments are needed, Hunnes added.

Specifically, she’d like to see a randomized controlled trial, that’s also longitudinal, be conducted. Only then will scientists — and ultimately consumers — know the true facts about artificial sweeteners.

“There’s a disconnect between what people believe vs. what science may actually be discovering,” she said. “They are replacing all this sugar with false sweetness and not doing themselves any favors.”

Until that happens, it’s still too soon to tell if artificial sweeteners will follow the same trajectory as margarine, she said.

For years, consumers were told that margarine was a safe and healthy alternative to butter because it didn’t contain saturated fats.

But then scientists discovered that the types of trans fats found in margarine were worse than saturated fats in terms of causing heart disease.