New research to be presented at this year's European Congress on Obesity (ECO 2025, Malaga, Spain, 11-14 May) suggests that weight loss programmes targeting a particular % weight loss are often failing, and that other factors should be considered including improvement of obesity-related complications, enhancing quality of life and overall physical and social functioning. The research is by an international team including Dr Sanjeev Sockalingam, Obesity Canada and the Centre for Addiction and Mental Health, Toronto, Ontario, Canada, and colleagues.
Identifying the most appropriate targets for obesity management is crucial due to the complexity of obesity as a disease associated with a myriad of health complications. Percentage weight loss has been a relied upon outcome measure for obesity treatment. However, this set target may result in a 'success or failure' result, leaving little room for other factors that make a real difference in the lives of people living with obesity. This scoping review aimed to synthesise evidence on percentage weight-based targets in obesity interventions and discuss their correlation with health outcomes.
The authors performed a review searching commonly used database including Cochrane, MEDLINE, and EMBASE up to July 29, 2024. Inclusion criteria were peer-reviewed studies in adults aged 18 years and over with obesity, focusing on weight reduction as a percentage of body weight. The researchers extracted data on study characteristics and analysed the targeted weight loss goals in relation to health benefits and outcomes.
The analysis yielded 30 studies, including randomised controlled trials (RCTs) and non-randomised trials published between 1992 and 2024. The studies predominantly targeted 3% to 10% weight loss, with a few aiming for higher thresholds. The review found a notable discrepancy between targeted and achieved weight loss, highlighting a frequent failure in reaching set goals. A third of studies did not provide post-study results for BMI or weight change. The rationale for selecting specific weight loss targets varied from disease-specific outcomes to improving quality of life. Few studies were powered to look at differences beyond weight change outcomes.
The nature of the scoping review meant that the authors were able look at where the frequent target of 5% weight loss came from and how studies set % weight loss as a goal. They found that the original 5% weight loss goal was set from a small number of well-resourced studies where this "target" of 5% was associated with health benefits, However, this new review did not look quantitatively at how often people hit this 5% weight loss target. The authors did observe, however, that in some of the studies in the review, only one third of patients achieved a weight loss target of 10% or more.
The review also showed that consideration should be given to moving beyond % weight loss targets and more recent literature recommends looking at broader health benefits beyond weight loss alone. The authors say: "Most of the studies in our review looked at populations where people were not only living with obesity, they also had a myriad of obesity-related conditions. Finally, we saw that in studies there is often an improvement in health outcomes with interventions such as nutrition, exercise and lifestyle, regardless of the weight loss outcome."
The authors conclude: "Despite the prevalence of established weight loss targets, our review suggests these are often unattainable and unsustainable for most participants. Obesity management interventions would benefit from shifting focus towards more comprehensive, patient-focused parameters, such as improvement of obesity-related complications, enhancing quality of life and overall physical and social functioning. This approach could provide more meaningful measures of success beyond mere weight reduction."
