Despite the low uptake of healthy lifestyle behaviors to achieve 5% weight loss or greater, the probability of weight loss increased among individuals with higher initial BMI.
The annual probability of 5% or greater weight loss in adults with overweight or obesity seeking health care in the United States was low despite the known benefits of clinically meaningful weight loss, according to the results of a study published in the Journal of the American Medical Association.
Overweight and obesity can be risk factors for numerous chronic diseases, including cardiovascular diseases, type 2 diabetes, and many cancers. More than 70% of US adults are afflicted by the conditions, and it is suggested that the longer obesity lasts, the greater the risk of chronic disease and mortality.
A 5% reduction in body weight has been generally agreed upon as clinically meaningful and has been associated with improved health measures, including in blood pressure, glucose, and cholesterol. There have been few large, longitudinal studies on body mass index (BMI) or body weight reduction among US adults with overweight or obesity.
Therefore, the investigators sought to assess the probability of 5% or greater weight loss, 10% or greater weight loss, BMI reduction to a lower category, and BMI reduction to the healthy weight category among US adults with overweight or obesity.
In total, 18,461,623 individuals were included in the study sample, which was comprised of 10,464,598 females (56.7%) and 7,997,025 males (43.3%). At the initial visit, 72.5% of individuals could be categorized as overweight (BMI of 25.0-29.9) or obese (BMI ≥ 30.0).
After a maximum of 14 years of follow-up, 33.4% of study participants with initial overweight and 41.8% of persons with initial obesity BMI category had a 5% or greater reduction in weight. Concurrently, 23.2% of persons with overweight and 2.0% of persons with obesity reduced BMI to the healthy weight (BMI of 18.5-24.9) category.
Overall, the adjusted annual probability of 5% or greater weight loss among individuals with overweight or obesity was 1 in 10. However, the probability increased with initial BMI category, from 1 in 12 individuals with initial overweight to 1 in 6 males and females with an initial BMI of 45 or higher.
Continuing, the adjusted annual probability of reducing BMI to the healthy weight category ranged from 1 in 19 individuals with initial overweight to 1 in 1667 individuals with initial BMI of 45 or higher. This probability was observed to be higher among females than males and was the highest among White females.
Additionally, compared with White males, the annual probability among Black males was slightly higher after initial overweight, but lower after initial class 3 or severe obesity categories.
The annual probability of 10% or greater weight loss was 1 in 24 individuals, ranging from 1 in 32 individuals with initial overweight to 1 in 11 individuals with initial BMI of 45 or higher. Furthermore, the annual probability of reducing BMI to a lower category was 1 in 13 individuals, ranging from 1 in 19 individuals with initial overweight to 1 in 8 individuals with initial BMI of 45 or higher.
Despite the overall low weight loss seen across the study participants, the investigators noted the greater likelihood of individuals with a higher BMI to have 5% or greater weight loss in comparison to lower BMI categories. The researchers agreed that this observation indicates the 5% weight loss target is reasonable for obesity management efforts.
“Clinicians and public health efforts can focus on messaging and referrals to interventions that support adults with excess weight in achieving and sustaining clinically meaningful weight loss,” the investigators discussed.
A separate category that is of concern to the study authors is the prevalence of obesity among adults 20 years of age or older, which increased from 25.7% in 2009 through 2010 to 42.4% from 2017 through 2018. They hypothesize that the findings can be explained by barriers in availability of and access to obesity management options, and that policies and strategies should be implemented to increase access and deal with the public health challenge.
Researchers did not differentiate between intentional and unintentional weight loss, which they wrote could have affected the patterns observed in the sample. They discussed that individuals with initial obesity who remained in the sample had a greater ability to engage in healthy lifestyle behaviors, which increased weight reduction in comparison to excluded participants.
Kompaniyets L, Freedman DS, Belay B, et al. Probability of 5% or greater weight loss or BMI reduction to healthy weight among adults with overweight or obesity. JAMA Netw Open. 2023;6(8):e2327358. doi:10.1001/jamanetworkopen.2023.27358