“There is controversy surrounding the use of artificial sweeteners because a lot of people are using them for weight loss,” says corresponding author on the new study, Kathleen Page. “While some studies suggest they may be helpful, others show they may be contributing to weight gain, type 2 diabetes and other metabolic disorders. Our study looked at different population groups to tease out some of the reasons behind those conflicting results.”

Page hypothesizes the discordancy in the science is somewhat due to the fact that many studies investigating the effects of artificial sweeteners on metabolic activity or the brain are conducted in mostly male subjects, often with normal weight. This new research set out to investigate the influence of artificial sweeteners on these processes across a broad cohort of men and women.

A total of 74 subjects were recruited for three experimental sessions. Each session began with the participant drinking a glass of liquid sweetened with either standard sugar, the artificial sweetener sucralose, or plain old unsweetened water.

About 20 minutes after consuming the drink the participants completed a food cue task inside a MRI machine. The task was designed to expose participants to images of different foods while measuring activity in several brain regions known to play a role in appetite.

Interestingly, the researchers detected increased responses to food cues in the medial frontal cortex and orbitofrontal cortex in women after consuming artificial sweetener compared to sugar or water. These differences were not detected in men. Obese subjects also showed increased medial frontal cortex activity after consuming artificial sweeteners.

The researchers also took blood samples from the participants to measure glucose and hormone responses to the different sweeteners. On this measure the study detected no significant differences.

The final part of the study investigated any potential behavioral changes after consuming artificial sweeteners. Two hours after drinking the liquid the participants were presented with a buffet of snack food and directed to eat as much or as little as they wanted.

Female subjects were found to consume more calories from the buffet after the artificially sweetened drink compared to the conventionally sweetened drink. Again, this difference was not detected in men.

“Our findings indicate that female individuals and those with obesity, and especially female individuals with obesity, might be particularly sensitive to greater neural responsivity elicited by sucralose compared with sucrose consumption,” the researchers conclude in the study. “This study highlights the need to consider individual biological factors in research studies and potentially in dietary recommendations regarding the use and efficacy of [artificial sweeteners] for body weight management.”

This is not the first study to try and home in on what effect artificial sweeteners may have on the body’s metabolic processes. A 2017 study zoomed in on the influence of sucralose on stem cells in fat tissue.

That study strikingly found sucralose can trigger a metabolic dysregulation in fat cells which potentially increases fat production. So, while artificial sweeteners certainly may lower the caloric content of some foods, they also may indirectly contribute to weight gain.

Page says her team’s new study is only the beginning of understanding exactly how artificial sweeteners may be influencing our brains and our behaviors. She is cautious of overstating her current findings but instead proposes other researchers seriously integrate different sex and weight groupings into future studies on this subject.

“Our study starts to provide context for the mixed results from previous studies when it comes to the neural and behavioral effects of artificial sweeteners,” adds Page. “By studying different groups we were able to show that females and people with obesity may be more sensitive to artificial sweeteners. For these groups, drinking artificially sweetened drinks may trick the brain into feeling hungry, which may in turn result in more calories being consumed.”

The new study was published in the journal JAMA Network Open.

Brain imaging reveals artificial sweeteners can increase food cravings [New Atlas]