Effect of Motivational Interviewing on a Weight Loss Program Based on the Protection Motivation Theory
What this study found
Both MI and MI plus intention-intervention significantly increased PMT constructs (susceptibility, severity, rewards, self-efficacy, response efficacy, costs) versus control at 2 months (P-values in the 0.001–0.014 range). Anthropometric data showed weight loss in MI group (74.25→72.50 kg, approx. −1.75 kg) and in MI plus intention group (77.33→76.74 kg, approx. −0.59 kg), while control changed minimally (75.91→75.70 kg, approx. −0.21 kg). BMI decreased by roughly 0.67 units in MI and 1.01 units in MI plus intention, with the control group showing little change. Between-group…
- Study & population
- Single-blind randomized clinical trial with pretest–posttest and control group conducted in Gorgan, Iran (IRCT2014051817736N1).
- Key limitation
- Short 2-month follow-up; female-only sample; single private clinic setting in Iran; generalizability limited; reliance on a researcher-made questionnaire for PMT constructs; some participants replaced after dropout; possible bias due to single-blind design
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Open PDFOriginal abstract
Background: The prevalence of overweight and obesity is on the increase the world over, which imposes an ever-increasing burden on societies and health care systems. Objectives: This study sought to investigate the effect of motivational interviewing (MI) on a weight-loss program based on the protection motivation theory (PMT). Patients and Methods: This randomized clinical trial study, comprising pretest-posttest with a control group, was conducted on 150 overweight and obese women attending a private nutrition clinic for the first time. Samples were randomly selected using the clinic’s records and then allocated to three groups (50 women in each group) receiving: 1) a standard weight-control program; 2) motivational interviewing; and 3) MI plus intention intervention. Data were collected using a researcher-made questionnaire through in-person interviews and were analyzed using SPSS (version 11) and statistical tests, including the Kruskal-Wallis test, one-way analysis of variance, paired t-test, and linear regression model. Results: In the two intervention groups, the PMT construct scores, namely susceptibility (P = 0.001), severity (P = 0.001), rewards (P =0.004), self-efficacy (P = 0.001), response efficacy (P = 0.001), and costs (P = 0.014), were significantly increased compared to those in the control group. The anthropometric status was statistically significant in the MI group (P = 0.001) and the MI plus intention-intervention group (P = 0.001) at 2 months’ follow-up, while in the control group, weight was meaningfully different after the intervention (P = 0.027). Weight was different between the groups after the intervention, with the Tukey test demonstrating that the differences were statistically significant between the control group and the MI group. Conclusions: Our results demonstrated that MI, combined with the implementation of intention intervention, increased weight loss and PMT construct scores in our study population.