Background: A meta-analysis examined differences in health-related quality of life (HRQoL) between seekers of surgical and non-surgical treatment, and non-treatment seekers, over and above differences that are explained by weight, age, and gender.

Methods: Our literature search focused on the 'Impact of Weight on Quality of Life-Lite' (IWQOL-Lite) and the 'Short Form-36' (SF-36) questionnaires. Included were studies published between 1980 and April 2006 providing (pre-treatment) descriptive statistics of adult overweight or (morbid) obese persons. Excluded were elderly and ill patient groups.

Results: Fifty-four articles, with a total number of nearly 100.000 participants, met the inclusion criteria. Persons seeking surgical treatment demonstrated the most severely reduced HRQoL. IWQOL-Lite scores showed larger differences between populations than SF-36 scores. After adjustment for weight, the population differences on the IWQOL disappeared. In contrast, the differences on the SF-36 between the surgical treatment seeking population and the other populations were maintained after adjustment for weight.

Conclusion: The IWQOL-Lite questionnaire predominantly reflects weight-related HRQoL, whereas the SF-36 mostly reflects generic HRQoL that is determined by both weight and other factors. Our meta-analysis provides reference values that are useful when explicating or evaluating obesity-specific (IWQOL-Lite) or generic (SF-36) HRQoL, weight, and demographic characteristics of obese persons seeking or not seeking surgical or non-surgical treatment.