Document Type : Original Article(s)


1 Professor, Department of Health Education and Promotion, Social Determinants of Health Research Center, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran

2 MSc Student, Department of Health Education and Promotion, Social Determinants of Health Research Center, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran

3 Associate Professor, Pediatric Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran

4 Assistant Professor, Department of Medical Epidemiology and Biostatistics, Shahid Sadoughi University of Medical Sciences, Yazd, Iran


BACKGROUND: The increased prevalence of overweight and obesity in children and adolescents is associated with type 2 diabetes, hypertension, dyslipidemia, and cardiovascular diseases. The theory of planned behavior (TPB) efficiently explains the ability of perceived behavioral control and possibly attitude to enhance the motivations of the obese people to lose weight. Our aim was to investigate the effect of TPB-based education on weight loss in obese and overweight adolescents. METHODS: In an interventional study, simple random sampling was used to select 86 overweight and obese adolescents aged 13-18 years in the pediatric clinic at the Isfahan Cardiovascular Research Institute. Anthropometric measures and TPB constructs were collected using a researcher-made questionnaire. The questionnaires were filled out before and six weeks after the intervention. Participants received 5 sessions of training based on the constructs of the TPB. RESULTS: A significant increase was observed in the mean score for knowledge and TPB constructs (attitudes, subjective norms, perceived behavioral control, intention, and behavior) six weeks after the educational intervention (P < 0.001). Moreover, significant decrease in body mass index (P < 0.001), weight (P = 0.001), and waist circumference (P < 0.001) of adolescents were found after the educational intervention. CONCLUSION: The TPB-based interventions seem to be effective in losing weight in obese and overweight adolescents. This theory serves as a helpful theoretical framework for health-related behaviors and can be an appropriate pattern to plan for educational interventions.   


  1. Rezapour B, Mostafavi F, Khalkhali H. "Theory based health education: Application of health belief model for Iranian obese and overweight students about physical activity" in Urmia, Iran. Int J Prev Med 2016; 7: 115.
  2. Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of childhood and adult obesity in the United States, 2011-2012. JAMA 2014; 311(8): 806-14.
  3. Jafari-Adli S, Jouyandeh Z, Qorbani M, Soroush A, Larijani B, Hasani-Ranjbar S. Prevalence of obesity and overweight in adults and children in Iran; A systematic review. J Diabetes Metab Disord 2014; 13(1): 121.
  4. Daniels SR. The consequences of childhood overweight and obesity. Future Child 2006; 16(1): 47-67.
  5. Rhoades DR, Kridli SA, Penprase B. Understanding overweight adolescents' beliefs using the theory of planned behaviour. Int J Nurs Pract 2011; 17(6): 562-70.
  6. Hirschler V, Buzzano K, Erviti A, Ismael N, Silva S, Dalamon R. Overweight and lifestyle behaviors of low socioeconomic elementary school children in Buenos Aires. BMC Pediatr 2009; 9: 17.
  7. Kong AP, Chan RS, Nelson EA, Chan JC. Role of low-glycemic index diet in management of childhood obesity. Obes Rev 2011; 12(7): 492-8.
  8. Luszczynska A, Sobczyk A, Abraham C. Planning to lose weight: Randomized controlled trial of an implementation intention prompt to enhance weight reduction among overweight and obese women. Health Psychol 2007; 26(4): 507-12.
  9. Behaviour-Based Safety-Coniugare produttivita e sicurezza comportamentale [Online]. [cited 2010]; Available from: URL:>EMPLATE=events.jsp
  10. Vafaeenajar A, Masihabadi M, Moshki M, Ebrahimipour H, Tehrani H, Esmaily H. Determining the theory of planned behavior's predictive power on adolescents' dependence on computer games. Journal of Health Education and Health Promotion 2014; 2(4): 303-11. [In Persian].
  11. Ajzen I. The theory of planned behaviour: Reactions and reflections. Psychol Health 2011; 26(9): 1113-27.
  12. Pakpour Hajiagha A, Mohammadi Zeidi I, Mohammadi Zeidi B. The impact of health education based on theory of planned behavior on the prevention of aids among adolescents. Iran J Nurs 2012; 25(78): 1-13. [In Persian].
  13. Guo JL, Wang TF, Liao JY, Huang CM. Efficacy of the theory of planned behavior in predicting breastfeeding: Meta-analysis and structural equation modeling. Appl Nurs Res 2016; 29: 37-42.
  14. Chung LM, Fong SS. Predicting actual weight loss: A review of the determinants according to the theory of planned behaviour. Health Psychol Open 2015; 2(1): 2055102914567972.
  15. Muzaffar H, Chapman-Novakofski K, Castelli DM, Scherer JA. The HOT (Healthy Outcome for Teens) project. Using a web-based medium to influence attitude, subjective norm, perceived behavioral control and intention for obesity and type 2 diabetes prevention. Appetite 2014; 72: 82-9.
  16. Rajati F, Sadeghi M, Feizi A, Sharifirad G, Hasandokht T, Mostafavi F. Self-efficacy strategies to improve exercise in patients with heart failure: A systematic review. ARYA Atheroscler 2014; 10(6): 319-33.
  17. Rajati F, Mostafavi F, Sharifirad G, Sadeghi M, Tavakol K, Feizi A, et al. A theory-based exercise intervention in patients with heart failure: A protocol for randomized, controlled trial. J Res Med Sci 2013; 18(8): 659-67.
  18. Cole TJ, Lobstein T. Extended international (IOTF) body mass index cut-offs for thinness, overweight and obesity. Pediatr Obes 2012; 7(4): 284-94.
  19. Pi-Sunyer FX, Becker DM, Bouchard C, Carleton RA, Colditz GA, Dietz WH, et al. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: Executive summary. J Clin Nutr 1998; 68(4): 899-917.
  20. Henson RK. Understanding internal consistency reliability estimates: A conceptual primer on coefficient alpha. Meas Eval Couns Dev 2001; 34(3): 177-89.
  21. Hazavehei SM, Taghdisi MH, Saidi M. Application of the health belief model for osteoporosis prevention among middle school girl students, Garmsar, Iran. Educ Health (Abingdon) 2007; 20(1): 23.
  22. Moradi F, Shariat F, Mirzaeian K. Identifying the effects of training of obesity prevention and weight management and the knowledge of clients to neighborhood health house in the city of Tehran. Journal of Health Education and Health Promotion 2013; 1(1): 33-40. [In Persian].
  23. Alizadeh SH, Keshavarz M, Jafari A, Ramezani H, Sayadi A. Effects of nutritional education on knowledge and behaviors of Primary Students in Torbat-e- Heydariyeh. Journal of Health Chimes 2013; 1(1): 44-51. [In Persian].
  24. Saffari M, Shojaeizadeh D, Ghofranipour F, Heydarnia A, Pakpour A. Health education & promotion-theories, models & methods. Tehran, Iran: Sobhan Publications; 2013. p. 55-7. [In Persian].
  25. Palmeira AL, Teixeira PJ, Branco TL, Martins SS, Minderico CS, Barata JT, et al. Predicting short-term weight loss using four leading health behavior change theories. Int J Behav Nutr Phys Act 2007; 4: 14.
  26. Zizzi SJ, Lima Fogaca J, Sheehy T, Welsh M, Abildso C. Changes in Weight Loss, Health Behaviors, and Intentions among 400 Participants Who Dropped out from an Insurance-Sponsored, Community-Based Weight Management Program. J Obes 2016; 2016: 7562890.
  27. Hamilton K, Daniels L, White KM, Murray N, Walsh A. Predicting mothers' decisions to introduce complementary feeding at 6 months. An investigation using an extended theory of planned behaviour. Appetite 2011; 56(3): 674-81.
  28. McConnon A, Raats M, Astrup A, Bajzova M, Handjieva-Darlenska T, Lindroos AK, et al. Application of the theory of planned behaviour to weight control in an overweight cohort. Results from a pan-European dietary intervention trial (DiOGenes). Appetite 2012; 58(1): 313-8.
  29. Kothe EJ, Mullan BA, Butow P. Promoting fruit and vegetable consumption. Testing an intervention based on the theory of planned behaviour. Appetite 2012; 58(3): 997-1004.
  30. Ahmadi Tabatabaei SV, Taghdisi MH, Nakheei N, Balali F. effect of educational intervention based on the theory of planned behaviour on the physical activities of Kerman health center s staff (2008). J Babol Univ Med Sci 2017; 12(2): 62-7. [In Persian].
  31. Caron F, Godin G, Otis J, Lambert LD. Evaluation of a theoretically based AIDS/STD peer education program on postponing sexual intercourse and on condom use among adolescents attending high school. Health Educ Res 2004; 19(2): 185-97.
  32. Karimy T, Saffari M, Sanaeinasab H, Khalagi K, Hassan Abadi M. Impact of educational intervention based on theory of planned behavior on lifestyle change of patients with myocardial infarction. Journal of Health Education and Health Promotion 2016; 3(4): 370-80. [In Persian].
  33. Giles M, McClenahan C, Armour C, Millar S, Rae G, Mallett J, et al. Evaluation of a theory of planned
  34. behaviour-based breastfeeding intervention in Northern Irish schools using a randomized cluster design. Br J Health Psychol 2014; 19(1): 16-35.
  35. Gardner RE, Hausenblas HA. Exercise and diet determinants of overweight women participating in an exercise and diet program: A prospective examination of the theory of planned behavior. Women Health 2005; 42(4): 37-62.
  36. Pasdar Y, Moridi S, Najafi F, Niazi P, Heidary M. The effect of nutritional intervention and physical activities on weight reduction. J Kermanshah Univ Med Sci 2011; 15(6): 427-34.
  37. Duangchan P, Yoelao D, Macaskill A, Intarakamhang U, Suprasonsin C. Interventions for healthy eating and physical activity among obese elementary schoolchildren: Observing changes of the combined effects of behavioral models. Int J Behav Med 2010; 5(1): 46-59.
  38. Kazemi F, Mazloom Z. Comparison of the effects of two diets (low-glycemic index and low-fat) on weight loss, body mass index, glucose and insulin levels in the obese women. J Birjand Univ Med Sci 2009; 16(1): 8-15. [In Persian].
  39. Nemet D, Barkan S, Epstein Y, Friedland O, Kowen G, Eliakim A. Short-and long-term beneficial effects of a combined dietary-behavioral-physical activity intervention for the treatment of childhood obesity. Pediatrics 2005; 115(4): e443-e449.