Diet and exercise effects on aerobic fitness and body composition in seriously mentally ill adults

Low exercise capacity and high obesity levels are the main characteristics of people with serious mental illness (SMI). We conducted a pilot study on the effects of a 3-month exercise and dietary intervention on the aerobic capacity and body composition of obese adults with SMI taking Olanzapine, a second generation antipsychotic medication known to induce weight increments. Fifty adults with SMI (15 males and 35 females) followed a 3-month weight loss intervention programme based on exercise and diet. Pre- and post-intervention, a submaximal O2 exercise test was performed in order to assess O2max anthropometric and body composition measurements were also performed. All participants were obese (body mass index (BMI): 33.61 ± 0.91 kg/m2). Pre- and post-intervention, a submaximal O2 exercise test on the treadmill was performed in order to assess O2max anthropometric and body composition measurements were also performed. Significant reductions in body weight, BMI, body fat and waist circumference were found from pre to post (p < 0.01). O2max was significantly improved in both genders (males: pre: 30.63 ± 2.06 vs. post: 33.19 ± 1.77 ml.kg-1 min-1, females: pre: 25.93 ± 1.01 vs. post: 29.51 ± 1.06 ml.kg-1 min-1, p < 0.01). A significant correlation was found between the change in O2max and the change in body weight and BMI (p < 0.05). Multiple regression analysis revealed that the relative change in O2max explained approximately 26% of the variance in the changes for both BMI (p = 0.07) and body weight (p = 0.06). A treatment of exercise and diet improves the aerobic capacity and body composition of obese adults with SMI, despite the use of Olanzapine.