Reporting Weight Loss 2021: Position Statement of the Dutch Society for Metabolic and Bariatric Surgery (DSMBS).

Prevailing recommendations on reporting weight loss after bariatric and metabolic surgery are not evidence-based. They promote the outcome metric percentage excess weight loss (%EWL), sometimes indicated as percentage excess body mass index loss (%EBMIL). Many studies proved that this popular outcome measure, in contrast to other weight loss metrics, is inaccurate and error-sensitive when comparing weight loss within and between studies. It is inappropriate for assessing poor weight loss response and weight regain as well. The percentage (total) weight loss metric is the best alternative. The Dutch Society for Metabolic and Bariatric Surgery (DSMBS) recommends to stop using the %EWL (or %EBMIL) metric as primary outcome measure in all cases and calls on the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) to propagate this evidence-based recommendation.