Adding an intensive lifestyle program to existing obesity treatment did not significantly increase weight loss overall in a 20-week clinical trial, though researchers found signs that the program may have benefited some aspects of metabolic health.
The randomized trial included 200 adults receiving obesity care through a public hospital in São Paulo, Brazil. Most were already taking obesity medications when the study began. Participants continued their usual medical care, while about half also took part in a program that combined nutrition education, physical activity guidance and behavioral support through a mix of in-person and remote sessions. Several researchers reported receiving personal fees from pharmaceutical companies that make obesity medications outside of this study.
The main goal was to see whether adding the lifestyle program would increase the number of people who lost at least 5% of their body weight after 20 weeks.
It did not.
About 21% of people assigned to the lifestyle program reached that target, compared with about 16% of those receiving usual care alone. The difference was not statistically significant, meaning the study could not establish that the added program was responsible for a greater likelihood of reaching the weight-loss goal.
The groups also did not differ significantly in overall weight change.
That does not mean the program had no effect. Researchers found favorable changes in several measures related to metabolic health among participants assigned to the lifestyle intervention, including LDL cholesterol, HDL cholesterol, triglycerides and a liver enzyme.
The findings, published in JAMA Network Open, highlight an important distinction between changes on the scale and changes in other measures of health. A lifestyle intervention may influence some cardiovascular and metabolic risk markers even when it does not produce substantially greater weight loss.
But the study also revealed a major challenge: keeping people in the program.
Nearly 40% of participants assigned to the lifestyle intervention dropped out, compared with about 21% of those receiving usual care. Some participants missed their final evaluation, while others reported difficulty following the program. Transportation, scheduling and getting time away from work also prevented some participants from completing follow-up visits.
Among the people who did complete the lifestyle program, researchers found greater weight loss and improvements in body measurements compared with the control group.
Those results need to be interpreted cautiously. Once researchers look only at people who remained in a program, the comparison is no longer as strong as the original randomized trial because people who complete an intensive intervention may differ in important ways from those who leave.
The researchers therefore could not determine whether sticking with the program itself caused the better results.
Another factor may have made additional weight loss harder to detect. About three-quarters of participants in both groups were already taking obesity medications when the study began, and many had already lost weight before entering the trial. The researchers noted that this may have left less room for the lifestyle program to produce additional weight loss.
The program also did not lead to clear differences between the groups in reported calorie, protein, carbohydrate, fat or fiber intake. The researchers cautioned that dietary intake can be difficult to measure accurately because it depended on participants reporting what they ate.
The trial was relatively short, lasting 20 weeks, so it cannot show whether any metabolic benefits would continue over time. The participants were also predominantly women, which limits how broadly the results can be applied.
Still, the study offers a more complicated picture of what lifestyle support may add to modern obesity treatment. In this group, adding structured nutrition, activity and behavioral support did not significantly increase the chances of reaching the study’s weight-loss target. At the same time, improvements in some metabolic measures suggest that body weight alone may not capture every potential effect of lifestyle treatment.
The published article did not report separate funding or support for the study. Several authors reported receiving personal fees outside the submitted work from pharmaceutical companies, including Novo Nordisk, Eli Lilly, Boehringer Ingelheim, Eurofarma, Merck, EMS and Brace Pharma.