The transtheoretical model in weight management: validation of the processes of change questionnaire

Abstract

Objective: The processes of change implied in weight management remain unclear. The present study aimed to identify these processes by validating a questionnaire designed to assess processes of change (the P-Weight) in line with the transtheoretical model. The relationship of processes of change with stages of change and other external variables is also examined.

Methods: Participants were 723 people from community and clinical settings in Barcelona. Their mean age was 32.07 (SD = 14.55) years; most of them were women (75.0%), and their mean BMI was 26.47 (SD = 8.52) kg/m(2). They all completed the P-Weight and the stages of change questionnaire (S-Weight), both applied to weight management, as well as two subscales from the Eating Disorders Inventory-2 and Eating Attitudes Test-40 questionnaires about the concern with dieting.

Results: A 34-item version of the P-Weight was obtained by means of a refinement process. The principal components analysis applied to half of the sample identified four processes of change. A confirmatory factor analysis was then carried out with the other half of the sample, revealing that the model of four freely correlated first-order factors showed the best fit (GFI = 0.988, AGFI = 0.986, NFI = 0.986, and SRMR = 0.0559). Corrected item-total correlations (0.322-0.865) and Cronbach's alpha coefficients (0.781-0.960) were adequate. The relationship between the P-Weight and the S-Weight and the concern with dieting measures from other questionnaires supported the validity of the scale.

Conclusion: The study identified processes of change involved in weight management and reports the adequate psychometric properties of the P-Weight. It also reveals the relationship between processes and stages of change and other external variables.

Copyright © 2011 S. Karger AG, Basel.

Figures

Fig. 1

Path diagram representing the four first-order factors model for processes of change in weight management. EmR = Emotional re-evaluation; WMA = weight management actions; EnR = environmental restructuring; WCE = weight consequences evaluation.

Fig. 2

Scores obtained on the processes of change subscales across the stages of change. EmR = Emotional re-evaluation; WMA = weight management actions; EnR = environmental restructuring; WCE = weight consequences evaluation;, PC = pre-contemplation; C = contemplation; Prep = preparation; A = action; M = maintenance.