A year-long European study examined how sweeteners and sweetness enhancers (S&SEs) affected weight maintenance and gut health in people with overweight or obesity. Replacing sugar with artificial sweeteners was linked to about 1.6 kilograms (about 3.5 pounds) more weight loss over a year and shifts in gut bacteria associated with short-chain fatty acid production, according to New Scientist. The World Health Organization recommended against using low-calorie sweeteners for weight control, saying the benefits of reducing body fat did not outweigh potential risks of type 2 diabetes and heart disease, according to New Scientist.
The SWEET consortium ran the trial in four European countries. Ellen Blaak’s team enrolled 341 adults with overweight or obesity and included a child cohort of 36 participants with an average age of 10 years. After an initial two-month low-calorie diet, adult participants lost about 10 kilograms on average and were required to reduce body weight by at least 5% and then maintain it. They were then followed for 10 months while choosing their own foods within a healthy diet. Participants were assigned to either replace sugar-rich products with low- or no-calorie sweeteners or continue consuming sugar. At least 16 types of sweetener were used, and participants could combine them. Biomarkers of S&SE intake rose in the sweetener group and fell in the sugar group at 12 months (P<0.001).
Adults in both groups maintained weight loss, but the sweetener group maintained more. At one year, the S&SE group had about 1.6 kilograms more weight loss than the sugar group. In the intention-to-treat analysis with imputed values, the S&SE group maintained 1.8 ± 0.7 kilograms more weight loss than the sugar group (P=0.01). A time-by-group interaction showed the sugar group weighed more than the S&SE group at months 4, 6, 9, and 12. At 12 months, hip circumference was more reduced in the S&SE group (P=0.04). No differences in physical activity were observed in a Maastricht subgroup (all P≥0.1).
Dietary records showed that adults and children reduced total intake of sugar-rich products while keeping sugar under 10% of calories. Among adults, the S&SE group reduced sugar-rich products more than the sugar group (P=0.0007). The S&SE group cut the energy percent from added sugar by 3.4 ± 1.2 percentage points more (P=0.05), reduced total sugar by 12.0 ± 5.5 grams per day more (P=0.03), and lowered the energy percent from total sugar by 2.4 ± 0.9 percentage points more (P=0.01). Group differences were mainly driven by beverages, milk, sugar, honey or jam, and candy.
The consortium evaluated whether S&SEs altered the gut microbiota. In a subset of adults at 12 months, the S&SE group showed higher abundance of multiple short-chain fatty acid (SCFA)-producing genera than the sugar group, and pathway analysis indicated upregulated methanogenesis, reflecting enhanced methane-producing potential. The analysis pointed to increases in SCFAs and fermentation gases. Short-chain fatty acids help regulate blood sugar, support heart health, and aid weight maintenance. “This shows that at least replacing sugars in the diet with non-caloric sweeteners may help you in maintaining body weight,” said Ellen Blaak at Maastricht University in the Netherlands, according to New Scientist.
The study reported no differences between groups in risk markers for type 2 diabetes and cardiovascular disease in the gut microbiota subgroup. At six months, the sweetener group had a larger decrease in body mass index and in both HDL and LDL cholesterol than the sugar group. Mild gastrointestinal side effects were more common with sweeteners during weight maintenance. Reports of abdominal pain or cramps (P=0.012), loose stools (P=0.014), and excess intestinal gas (P=0.002) were higher in the S&SE group. Overall adverse events were also more frequent in the S&SE group during weight maintenance (P=0.047). Nine serious adverse events occurred: five in the sugar group and four in the S&SE group. In the S&SE group, serious events included laparoscopic cholecystectomy and pulmonary embolism; in the sugar group, they included a surgical procedure unrelated to the intervention and angina pectoris. All participants recovered without further consequences.
Among children, there was no difference in body mass index between groups. The BMI-for-age z-score decreased by 0.30 ± 0.39 (P=0.001), and waist and hip circumferences fell, with no differences between groups.
The trial tested whether adding S&SEs to a healthy, low-sugar diet could help people maintain weight loss and sustain cardiometabolic health. The approach was hypothesized to increase dietary palatability and improve adherence to sugar-reduction targets. Greater adherence in the S&SE group appeared to track with the larger maintained weight loss. The study ran during the COVID-19 pandemic and faced disrupted follow-up, higher dropout, and logistical hurdles related to travel restrictions and safety protocols.
The findings arrived amid mixed evidence about the health effects of low- and no-calorie sweeteners. Some studies reported neutral outcomes, while others raised possible links to cardiovascular risk, including heart attack and stroke, and suggested that small amounts of some sweeteners could promote blood clotting and inflammation. Researchers at the University of Colorado previously reported that zero-calorie sweeteners such as erythritol could cause harm within hours of consumption. “Our understanding of the microbiome is still in its infancy,” said Eran Elinav at the Weizmann Institute of Science in Israel, according to New Scientist. Elinav added that it remained unclear whether the microbiome changes in the sweetener group reflected weight loss, the sweeteners, or both, according to New Scientist.
Produced with the assistance of a news-analysis system.