Background/Objectives:We aimed to extend the actual overweight discussion with new unbiased Swiss conscript data from 2005 to 2006, and to present for the first time Swiss data on body mass index (BMI) before 1950 and for the late-nineteenth century.Subjects/Methods:For this study, 19-year-old Swiss male conscripts (draft army; Cantons Bern, Zurich, Basel-Stadt and Basel-Land) from the census of 1875-1879, 1933-1939 and 2005-2006 (N=28 033; 2005-2006 census) were included. BMI distribution (World Health Organization (WHO) classification) and social stratification (International Labour Organization classification) were main outcome measures.Results:Mean BMI of 19-year-old men in Switzerland increased in the 50 years between the 1870s and the 1930s by 0.80 kg/m(2) and between the 1930s and 2005 by 1.45 kg/m(2). The modern BMI sample is much more right skewed and s.d. is higher. Obesity prevalence (according to modern WHO classification) has increased by a factor of 105 from 1870s until present. Over 23% of our representative sample of Swiss men in 2005-2006 had a BMI of over 25 kg/m(2). In 2005-2006, contrary to the nineteenth century, unskilled workers had articulately higher BMI values at the 75th, 90th and 95th percentile than students; 12% of unskilled workers were obese against 2% of students.Conclusions:It thus seems that BMI relations between the upper and the lower end of the socio-economic strata changed inversely from the late-nineteenth century to 2005-2006. We further propose that the phenomenon of massive right-skewing BMI distribution between the 1930s and 2005-2006 affected the lower socio-economic strata to a far greater extent than the higher socio-economic group.