Publication Date

2011-07-18

Availability

Open access

Embargo Period

2011-07-18

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Psychology (Arts and Sciences)

Date of Defense

2010-05-07

First Committee Member

Barry E. Hurwitz

Second Committee Member

Maria M. Llabre

Third Committee Member

William K. Wohlgemuth

Fourth Committee Member

Alan M. Delamater

Fifth Committee Member

Jennifer B. Marks

Abstract

Approximately one-third of U.S. adults are at increased risk for life-threatening diseases such as atherosclerosis and type 2 diabetes mellitus. Such individuals are considered healthy without any diagnosed cardiometabolic conditions but may have a constellation of cardiometabolic complications that include obesity, glucose intolerance, hyperinsulinemia, dyslipidemia, hypertension, insulin resistance, and hypertriglyceridemia. When most of these preclinical conditions comorbidly occur, the condition has been referred to as metabolic syndrome (MetS). MetS is considered to reflect one or more early pathophysiological processes in cardiometabolic disease; however, the extent to which these complications and their underlying pathophysiology interact with behavioral factors such as stress, diet, and physical activity have not been clearly established. For example, diet consisting of high total caloric intake and high fat composition is posited to contribute to obesity and other cardiometabolic risk factors, but research is inconsistent regarding the effect of psychological distress (i.e., anxiety, stress, depression, anger) on dietary intake and whether dietary intake mediates a relationship between distress and preclinical cardiometabolic disease risk. One factor that has been suggested to play a role in the distress – dietary intake relationship is eating style. Research on eating styles has identified four main types that may be related to distress and dietary intake: restrained, disinhibited, emotional, and external eating. Restrained eaters consciously restrict food intake to control body weight and body shape. Disinhibited eating refers to overeating that occurs following failure of restraint. Emotional eaters consume foods to reduce and alleviate negative emotions, such as anxiety. External eating occurs in response to immediate food-related external stimuli, regardless of internal physiological cues of hunger. Current evidence suggests each of these eating styles moderates the relationship between distress and dietary intake. There is also some research to suggest a relationship between eating styles and weight gain, body mass index (BMI), and development of obesity. However, no study has examined the interrelationships among psychological distress, eating style, and central obesity, and whether these relationships differ according to gender. Moreover, the extent to which distress and eating style may be associated with cardiometabolic risk beyond obesity is unknown. Thus, the main aim of the present study was to test a model of mediation and moderation to evaluate how psychological distress, eating styles, dietary intake, and gender are associated with measures of cardiometabolic risk in healthy individuals (Figure 1). Four hundred sixty-four participants contributed data from two different studies: Obesity, Metabolic Syndrome, and Meal-Related Glycemia (SUGAR) and Markers Assessing Risk for Cardiovascular Health (MARCH). All participants were aged 18-55 years, had no major systemic disease, were not using medications having a cardiovascular, carbohydrate, endocrine, or psychiatric effect, and had no history of substance or alcohol abuse or dependence. The study employed a structural equation modeling (SEM) approach to assess the following aims: 1) to develop composite, latent factors to reflect psychological distress, eating style, and dietary intake using confirmatory factor analysis (CFA) and to develop a hybrid model of cardiometabolic risk; and 2) to simultaneously test the interrelationships among factors in a comprehensive model so that the strength of direct and indirect effects can be evaluated while statistically controlling for the other factors and covariates in the model. Latent factor models of psychological distress and eating style fit the data and were statistically acceptable, and a hybrid model of cardiometabolic risk fit the data and its CFA components were acceptable. A latent factor model of dietary intake would have likely fit the data and been statistically acceptable given the high intercorrelations among dietary variables, but no such factor was created because dietary variables failed to confirm the hypothesized associations with other model components (e.g., waist girth, eating styles); thus, these measures were excluded from further SEM analyses. Final model results showed that psychological distress was positively related to restrained, emotional, and external eating styles, but only restrained eating was directly associated with greater waist girth. Distress was not directly related to cardiometabolic risk, but an indirect effect was found in which higher levels of distress led to greater waist girth via higher levels of restrained eating. Waist girth, in turn, served as a significant mediator between restrained eating and worse insulin sensitivity, higher blood pressure, diminished glucose tolerance, and greater dyslipidemia. These effects were significant when controlling for age, gender, education, and physical activity, and when analyzed in a comprehensive SEM model simultaneously including distress, eating style, and cardiometabolic risk variables. Of note, results suggest the possibility for a reversed effect such that waist girth leads to restrained eating. Findings also suggest that emotional eating may lead to distress. In contrast, the relationship between distress and the other two eating styles, restrained and external eating, appeared unidirectional such that distress leads to restrained and external eating but not the reverse. Future studies using longitudinal data are needed to better understand these relationships in regards to causality. Data from the MARCH subsample was excluded from the above final modeling analyses because eating style data were only available for the SUGAR subsample. Thus, the role of gender in how distress, eating styles, and cardiometabolic risk are interrelated could not be examined due to the small number of women in the SUGAR study (n = 38). It remains unknown whether the significant effect of distress on each of the eating styles found in the current study was driven primarily by men, women, or both equally. Similarly, the sample size would not permit the evaluation of whether gender moderated the effect of restrained eating on central obesity. Given that women in the current study reported more restrained, emotional, and external eating than men, future studies with larger samples should follow-up by assessing for potential moderating effects of gender. The present findings suggest that decreasing restrained eating style may lead to less central fat deposition and hence reduced cardiometabolic risk. Such “non-diet” interventions show potential for improved cardiometabolic health, but more research is needed. Particularly needed are studies examining prevention and intervention outcomes based on type of restrained eating – flexible versus rigid – to better understand how these different subtypes operate and how they can be altered effectively to improve health.

Keywords

eating styles; emotional eating; restrained eating; external eating; psychological distress; obesity

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