For the trial, researchers asked 74 adults, ages 18 to 35, to come to a lab on three separate occasions. The group included women (58 percent) and men, and overall 37 percent were at a healthy weight, 32 percent were overweight, and 31 percent were obese. During each lab visit, researchers asked participants to drink one of three different beverages: water; a drink containing the artificial sweetener sucralose; or a drink sweetened with sucrose, a sugar found naturally in a variety of foods. After drinking, participants underwent brain scans while being shown images without food or with high-calorie, low-calorie, sweet, or savory foods. The researchers used functional magnetic resonance imaging (fMRI) to measure changes in blood flow to different areas of the brain. RELATED: Low- and No-Calorie Sweeteners May Not Help With Weight Loss They discovered that when women who drank sucralose-containing beverages prior to being scanned viewed high-calorie or sweet foods, they had more activity in the areas of the brain thought to be responsible for food cravings than men who had the identical drink and viewed the same images. The results also indicated that people with obesity — but not those with overweight or a healthy weight — viewed savory foods, those same craving-related areas of the brain lit up. To see how the different sweeteners impacted appetite, researchers also asked participants to eat as much as they wanted from a buffet about two hours after they consumed a drink with sucralose, sucrose, or only water. Women — but not men — ate more total calories after they’d had a sucralose beverage. “Based on these findings, I would suggest that the artificial sweetener sucralose may not be as effective for reducing appetite and food cravings in women and people with obesity, whereas for men and healthy-weight people, it might be a suitable alternative to reduce sugar intake,” says the study’s senior author, Kathleen Page, MD, the co-director of the Diabetes and Obesity Institute at the Keck School of Medicine at the University of Southern California in Los Angeles. RELATED: 7 Foods With More Sugar Than You Think

Interpreting the Results

While the study was done in a lab and doesn’t perfectly replicate real-world conditions, the results do indicate that artificial sweeteners may not be a magic bullet for weight loss, particularly among certain populations. Sucralose, which is sold individually as a sweetener and used to manufacture many packaged foods, including beverages, is 600 times sweeter than sugar, according to the U.S. Food and Drug Administration (FDA). It’s possible that sucralose evoked a stronger mental response among women because the participants were all in their prime reproductive years, when their bodies may be hardwired to be more sensitive to nutrient cues in the brain, Dr. Page says. As for why people with obesity may have greater appetite signals when they drink beverages containing sucralose, Page says that one possibility is that they consume more artificial sweeteners overall, and could have grown so accustomed to those sweeteners that they no longer associate sweets with high-calorie foods. “Since sweet taste and calories usually go together in foods, the artificial sweetener is intended to ‘fool us’ into thinking we are getting the taste without the calories, and this is true, but people often misuse this information to take extra amounts of food, thus defeating the purpose,” says George Bray, MD, a professor emeritus at the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge who was not affiliated with the clinical trial. RELATED: Which Sugars Are Good for You — and Which Ones to Avoid

Sweetened beverages have been tied to increased appetite and food cravings before. For example, a study published in July 2016 in Diabetes used fMRI to examine changes in the brain when adolescents with normal weight or with obesity consumed drinks with fructose or glucose. Fructose and glucose are sweeteners derived from corn. Only teens with obesity experienced a surge of activity in the areas of the brain that trigger food cravings. Another study, published in April 2019 in Nutrition, examined the effect of glucose, fructose, or sucrose consumption on brain activity in healthy young men using fMRI. In this study, the men had an immediate response in the area of the brain responsible for satiety cues when they consumed glucose, but a delayed satiety reaction when they had fructose or sucrose, which might contribute to additional food consumption. Findings on how artificial sweeteners impact appetite have been less clear-cut. A research review published in Nutrients in September 2020 examined results from 20 previous functional MRI studies designed to test the effect of sugars and artificial sweeteners on brain activity, cravings, and appetite and found mixed results. This analysis didn’t find a clear or consistent pattern for brain activity associated with various types of sweeteners, and the researchers concluded that larger, longer clinical trials are needed to get a good picture of these relationships. RELATED: Is Sparkling Water Good or Bad for You?

The Best Approach to Sweeteners Is Moderation

“Long-term studies are necessary,” Page agrees. “Findings from current studies are inconclusive regarding which sweetener, and how much sweetener, is ideal for people who want to lose weight or maintain weight.” People who want to satisfy a craving for sweets should eat whole foods like fruits because they provide fiber to slow digestion and increase fullness, Page says. Sugar-sweetened beverages, whether they have sucralose or another ingredient creating that flavor, should be consumed in moderation or avoided altogether when people are trying to shed excess pounds or maintain a healthy weight, Page advises. “The best drink to consume to avoid sugar is water,” she says. “Both regular water and sparkling water without sweetener are fine.”