In this article, we aim to explain international differences in socio-demographic structure of population among people around retirement age. We further test if transition into retirement is an important factor for obesity. Using Survey of Health, Ageing and Retirement in Europe (SHARE) data, we first document that the Czech Republic has a significant and increasing trend in body mass index (BMI) and obesity (BMI > 29.99) for both men and women aged 50–70 years compared to other countries. Men have much higher level of BMI in comparison to many other European countries, whereas BMI of women is comparable to Estonia and Slovenia. However, we show a little evidence that underlying structure of Czech population with respect to education, occupation, health, age, and so on may explain increasing trend as well as higher level of obesity when compared to other European countries. Furthermore, we show that the transition into retirement is not associated with an increase in BMI. Using fixed effect model, we found that the obesity is directly related to increasing trend in obesity already before entering the retirement.