Artificial sweeteners such as aspartame or saccharin have previously been reported to increase feelings of hunger and, subsequently, food intake. This has cast a shadow over sweeteners as promoters of obesity. However, a new and more robust study suggests quite the opposite. Researchers found no evidence that sugar replacements, whether artificial or natural sweeteners, make people hungrier. Moreover, they found that these compounds help to reduce blood sugar levels. This means that these compounds actually reduce your appetite, in the same way that your hormones respond to sugary food.

These findings are particularly important for people at risk of type 2 diabetes, who require a safer alternative to sugar without the compromise of increased hunger or cravings.

“The use of sweeteners and sweetness enhancers has received a lot of negative attention, including high profile publications linking their consumption with impaired glycaemic response, toxicological damage to DNA and increased risk of heart attack and stroke. These reports contribute to the current befuddlement concerning the safety of sweeteners and sweetness enhancers among the general public and especially people at risk of metabolic diseases,” said lead author Graham Finlayson, who is a Professor of Psychobiology at the University of Leeds’ School of Psychology.

“Our study provides crucial evidence supporting the day-to-day use of sweeteners and sweetness enhancers for body weight and blood sugar control.” 

Zero-calorie sweet tooth

The study involved 53 overweight or obese adults. The researchers closely monitored how their bodies reacted to consuming biscuits with either sugar or two types of sweeteners: Stevia, a natural sugar substitute, or Neotame, an artificial sweetener. Previously, other studies focused on studying the effects of artificial sweeteners in beverages like Diet Coke. This time, the researchers tried solid food, more than one single sweetener (most studies focus on aspartame), and included more volunteers of both sexes.

The participants went through three two-week phases, each time eating biscuits filled with different sweeteners: sugar, the natural sweetener Stevia, or the artificial sweetener Neotame. Between each phase, there was a break of 14-21 days. The first and last days of these phases were conducted in a lab setting.

Upon arriving at the lab after fasting overnight, researchers collected blood samples from the participants to measure baseline glucose, insulin, and appetite-related hormone levels. Participants also provided ratings of their hunger and food preferences.

After eating the biscuits, participants reported on their feelings of fullness over several hours. The study also monitored changes in glucose and insulin levels, along with ghrelin (the hunger hormone), glucagon-like peptide 1, and pancreatic polypeptide levels —hormones that play roles in food intake and appetite.

The findings revealed that neither type of sweetener affected appetite or hormonal responses when compared to sugar. However, insulin and blood sugar levels were notably lower two hours post-consumption, suggesting a difference in how the body processes these sweeteners.

“The findings show that sweeteners are a helpful tool to reduce intake of added sugar without leading to a compensatory increase in appetite or energy intake, thereby supporting the usefulness of sweeteners for appetite, energy and weight management,” said co-author Professor Anne Raben, from the University of Copenhagen, Denmark. 

It’s still murky

In 2020, researchers at Boston Children’s Hospital wanted to see what happens when soda drinkers switch to drinking water or beverages that are artificially sweetened. The researchers recruited 203 adults who consumed at least one sugary beverage daily. After following the participants for a year, the researchers did not find any significant differences in weight gain between those who consumed artificially sweetened beverages and those who used sugar soda. No differences in markers of metabolic health, including cholesterol or triglyceride levels, were reported either.

“Simply restricting sugar from foods without substitution may negatively impact its taste or increase sweet cravings, resulting in difficulties sticking to a low-sugar diet. Replacing sugars with sweeteners and sweetness enhancers in food products is one of the most widely used dietary and food manufacturing strategies to reduce sugar intake and improve the nutritional profile of commercial foods and beverages,” said lead author Dr. Catherine Gibbons, Associate Professor at the University of Leeds.

Despite the findings, artificial sweeteners remain controversial. Despite decades of widespread use, it’s still unclear whether consuming them heavily for many years can have unintended adverse health effects. One recent 2023 study, for instance, linked aspartame to learning and memory deficits.

“The short answer is that artificial sweeteners are probably better than sugar, but not by much,” Dr. Robert Lustig, an obesity expert and professor emeritus at the University of California, San Francisco, told the New York Times.

The findings appeared in The Lancet.