['The aim of the present study was to examine the impact of obesity and physical activity on the health and wellbeing of patients with breast cancer shortly after the adjuvant treatments.', 'A total of 537 women aged 35 to 68 years with newly-diagnosed breast cancer were enrolled into the exercise intervention study. The physical activity, physical performance (2-km walking test), cardiovascular risk factors, quality of life (EORTC-QoL-C30), co-morbidities and body-mass index (BMI) were measured after the adjuvant treatments.', 'Overall, 191 (39%) patients were overweight (BMI=25-30) and 85 (17%) obese (BMI ≥ 30). Physical activity and performance (p<0.001 and p<0.001), QoL (p<0.001) and high density lipoprotein (HDL)-cholesterol decreased (p<0.001) whereas age (p=0.009), co-morbidities (p<0.001), hypertension (p=0.011), metabolic syndrome (p<0.001), low density lipoprotein (LDL)-cholesterol (p=0.0043), triglycerides (p<0.001), glucose (p<0.001) and insulin (p<0.001) increased linearly with BMI. Higher waist circumference (p=0.0011), triglyceride (p=0.020), insulin (p=0.0098), rate of metabolic syndrome (p=0.028), and lower HDL-cholesterol (p=0.012) and QoL (p<0.001) were associated with low physical activity. Physical activity and BMI were the most important determinants of physical performance (p<0.001 and p<0.001, respectively).'] Are obesity and physical inactivity related to impaired physical health of breast cancer survivors?