AIM: The aims of the present study were to investigate the effectiveness of exercise intervention provided by a medical support team specializing in lifestyle-related diseases in the treatment of elderly lower extremity osteoarthritis and to examine the influence of bodyweight decrease on changes in the evaluation indexes. METHODS: Participants were 61 patients (57 women and 4 men, aged 68.3 ± 9.6 years) with lower extremity osteoarthritis (109 total diseased joints) and either one or more of the following diseases: obesity, metabolic syndrome and type 2 diabetes. Indexes relating to metabolic diseases, orthopedic disorders, lifestyle activity level and health-related quality of life (HRQOL) were obtained before and after exercise intervention. RESULTS: The numbers of patients with obesity, metabolic syndrome, type 2 diabetes, gonarthrosis and coxarthrosis were 56, 49, 32, 56 and 9, respectively. The mean intervention period was 4.7 ± 1.6 months (2-10.8 months). Indexes relating to metabolic diseases and orthopedic disorders, activity level and HRQOL were all significantly improved after intervention (P < 0.05). Bodyweight decreased by 10.3% and showed a correlation with other evaluated items. Five explanatory variables were extracted through multiple regression analysis that bodyweight reduction rate was set as the criterion variable: changes of bodyweight, body mass index, percent body fat, glycated hemoglobin and total energy expenditure per bodyweight. CONCLUSION: The exercise intervention provided by our medical support team clearly improved indexes relating to metabolic diseases and orthopedic disorders. In addition, decreased bodyweight was related to improvements in metabolic factors, motor function and HRQOL.