Minimal Reporting Requirements for Weight Loss: Current Methods Not Ideal

Background: There is variety in the reporting of weight loss outcomes within the bariatric literature. Our aim is to compare methods of reporting weight loss in surgical and medical studies, and in addition look for a minimal reporting requirement that allows meaningful comparison. Method: A review of methods of reporting weight loss in studies published during 2004 was conducted. Bariatric surgical studies included all reports from MEDLINE-listed journals, and medical studies included reports of non-surgical weight loss from 9 leading journals. Results: 65 surgical and 36 non-surgical reports were retrieved. There were 3 common (>20% of reports) methods of reporting in the surgical literature; mean weight, percentage of excess weight loss (%EWL) and body mass index (BMI), and 4 in the medical literature; mean weight loss, weight, percentage weight loss and BMI. %EWL was reported in 2/3 of surgical reports and in none of the non-surgical. The origin of ideal weight for %EWL calculations was reported in 10 (23%) of these studies and included 5 differing definitions. All methods of reporting other than those using "ideal weight" can be calculated from mean weight and BMI at all time-points. Conclusion: There is complexity and confusion in the reporting of bariatric surgery weight outcomes when calculations are based on ideal weight. Providing weight (kg) and BMI (kg/m²) at all time-points allows the reader to interpret and compare the results in the context of the population of interest. These two measures should be provided as a minimum by all journals reporting on intentional weight loss.