Psychological predictors/moderators of weight loss outcome

Abstract

Purpose. Obesity is a public health problem because of its association with numerous medical complications, causing increased morbidity and mortality in the United States. The role of emotion and cognition in weight control literature has been inconclusive. The purpose of this study is to investigate the relationship between psychological well-being, self-efficacy and weight loss outcome.;Methods. A secondary analysis of a one-year randomized controlled clinical trial to identify baseline variables that predicted and/or moderated weight loss outcome. The sample consisted of 588 overweight participants with a mean BMI of 35.6 kg/m2. Variables found to be correlates of weight loss in the primary analysis were repeated as logistic regressions to determine if they were also predictors of weight loss. These include: (1) increased walking, (2) decreased calories and (3) increased self-monitoring. Logistic regressions were computed to determine if participants' baseline psychological general well-being and self-efficacy predicted weight loss. Moderation was assessed by examining how adjusting for psychological variables affected the relationship between the intervention variables and fourth quarter changes in weight. The sample was assessed as a whole and then divided according to gender to determine if the importance of the psychological characteristics varied by sex.;Results. The correlates of weight loss were also predictive of change in weight: (1) increased walking (p = 0.0017); (2) decreased calories (p < 0.0001) and (3) frequency of self-monitoring (p = 0.0073). The Psychological General Well-Being Survey (p = 0.82), Exercise Confidence Survey (p = 0.83) and Eating Habits Confidence Survey (p = 0.52) were not found to predict fourth quarter change in weight and did not moderate the relationship. Attendance at computer sessions and frequency of self-monitoring were not significant predictors of weight loss in men.;Conclusions. The present study found a causal relationship between an increased amount of walking, decrease in calories and increase in self-monitoring. However, no relationship was found between baseline psychological characteristics and weight loss outcome. In contrast to previous research, there was little distinction between men and women in this sample. The absence of gender differences may be more indicative of women outnumbering men in this sample.