Outcome research in obesity. Lesson from the QUOVADIS study

Outcome research in obesity is aimed at the identification of clinically meaningful goals. Over the years, the focus has moved from surrogate health markers to cardiovascular risk and survival. The 7-10% weight loss recommended by guidelines is a target easily attained with any treatment, but does not guarantee physical and psychological benefits unless it is accompanied by weight loss maintenance, a target very difficult to achieve with either behavior treatment or pharmacological intervention. A reduced cardiovascular risk profile is associated with weight loss, irrespective of the treatment program. In contrast, no controlled studies have so far documented an increased survival, but evidence has been provided by epidemiological surveys. Also bariatric surgery, promoting a larger weight loss and good weight loss maintenance, has failed to demonstrate an improved survival. Health-related quality of life is an additional significant outcome, approved by international agencies. Concern regarding a possible detrimental effect of dieting on mood and depression is not substantiated by the results of controlled studies. The high prevalence of obesity and its consequences pose a serious and unresolved challenge to the medical community and the definition of outcome measures is a key issue for the assessment of results