Several studies have been performed on the relationship between working conditions and health. Numerous parameters still require further study, including working hours and obesity among different groups, specifically older workers in national, regional, and international levels. Working hours have considerable effects on the socio-cultural, psychological, and economic aspects of people's lives and health. While long working hours increases income level and raises living standards, it increases the risk of certain health problems. This study investigated whether working hours are associated with obesity in upper-middle-aged workers. The Survey of Health, Ageing and Retirement in Europe (SHARE) dataset was used for the analyses. Analyses were carried out by means of a Cox regression of the panel dataset created with the data in question, surveyed by European Commission to 12,000 participants. The survey was performed in Austria, Belgium, Switzerland, Germany, Denmark, Spain, France, Greece, Italy, the Netherlands, Sweden, the Czech Republic, Poland, and Ireland. We found that in most countries, especially Sweden and the Netherlands, upper-middle-aged employees working > 59 hours per week are more likely to gain weight than their counterparts working < 59 hours. Our findings raise awareness of obesity in older workers, and highlight the need to regulate working conditions and hours in the European Union and other countries.