Aims: To determine the effects of a nutrition and exercise weight management program supported by social cognitive theory on self-efficacy, body mass index and psychosocial functioning in adolescents aged 10-13 years (n=119). Methods: A quasi-experimental intervention to improve self-efficacy for eating and exercise weight management for 59 overweight adolescents aged 10-12 years who participated in a 6-month weight-control self-efficacy programme.The control group consisted of 60 overweight adolescents. The changes in BMI, lifestyles and psychosocial functioning through self-efficacy beliefs, were assessed using the chi-squared and t-test.
Results: Weight loss at 6 months was 0.05 kilograms of baseline body weight, and self-efficacy scores increased in the range of 0.58 to 0.75 among adolescents in the intervention group, while for those in the control group, self-efficacy scores decreased by -0.15 to -1.03. Self-esteem was one of the psychosocial factors that caused the overweight and obese adolescents to eat appropriately and intend to exercise regularly. Thus, this intervention had the most significant impact on adolescents’ self-esteem (t=3.2, p=0.002) using the paired t-test between the pre- and post-tests.
Conclusions: Findings were consistent with the social cognitive theory, namely that improvement in self-efficacy over time supports greater weight loss. Adherence to exercise and appropriate eating can benefit weight-loss outcomes because individuals’ cognitive capability and belief in the intervention are taken into consideration by engaging them in pre-set actions and health outcomes.