The primary outcome variable will be body weight and secondary outcome variables will be biomedical ( body mass , body fat percentage , muscle mass , waist-hip circumference ratio , systolic and diastolic blood pressure , low-density lipoprotein , high-density lipoprotein , total cholesterol , triglycerides , blood glucose and insulin levels ) , psychological ( quality of life , motivation , risk perception , outcome expectancy , intention , action self-efficacy , maintenance self-efficacy , goal setting and planning ) , and behavioural ( self-reported diet intake , and physical activity involvement ) measures .