Background Previous research has revealed a clear relationship between weight gain of persons and their metabolic diseases developing later. These studies have covered only short periods lasting 4-8 years. Our goal was to collect decades' old and often life-long anthropometric data and correlate the figures with the presence of hypertension and diabetes or both. Methods A retrospective international study was planned and organized to compare self-recorded data of lifelong weight gain among 60-70-year-old patients, analyze their correlation with metabolic diseases they developed, with special attention to women's weight gain around pregnancy, delivery and menopause in primary care settings in Germany, Hungary, Italy, Slovakia and the Ukraine. Results Of the recruited 815 participants, 319 men and 496 women presented all the required data. Diabetics of both genders had the highest baseline weight at 20 years of age. The weight and BMI of the whole study population increased steadily until their seventies, but to a lesser extent after their fifties. Compared to the control group, changes over decades were the greatest among diabetics and also greater among patients with hypertension. Weight increase in the first decades (20-30-year-old men and 30-40-year-old women) was a significant risk factor for the development of diabetes (OR = 1.044; p = 0.002; 95 % CI: 1.01-1.07). Among patients with diabetes and hypertension, both diagnoses were set up earlier than among those with a single morbidity. Among females, weight increase around pregnancy and menopause correlated significantly with higher odds for the diagnoses of diabetes and/or hypertension, irrespective of the number of children. Conclusions During their decade-long relationship with their patients, family physicians are expected to identify the higher weight gain of their patients, especially among younger generation and intervene, if necessary.