Effects of Psychosocial Stress on Food Preference, Caloric Intake, and Obesity Risk Open Access

Abstract

In recent decades, the prevalence of obesity has increased steadily worldwide leading to a concomitant surge in the incidence of related metabolic complications and chronic diseases. While obesity can be explained in biological terms as the consequence of prolonged positive energy imbalance (i.e., energy intake exceeding energy expenditure), a number of complex psychological, social, and environmental factors affect both sides of this equation. Stress-induced eating has received substantial attention in both human and animal model research. Yet, the stress-eating-obesity relationship has not been fully elucidated, and the role of the food environment in the stress-eating relationship has only recently gained interest. Previous studies using social subordination as a model of chronic stress among group housed female rhesus monkeys have shown that subordinate females consume fewer kilocalories than dominant animals when a typical laboratory chow diet is available but become hyperphagic in a rich dietary environment providing access to chow and a more palatable diet, high in fat and sugar. The present investigations expanded upon this work using long-established and recently formed groups of female rhesus monkeys. Significant findings included: 1) Pharmacological antagonism of the physiological stress response system attenuated caloric intake in a rich dietary environment among socially subordinate female rhesus monkeys within long-term stable social groups. 2) Formation of new social groups led to marked weight loss among all subjects within a standard laboratory chow dietary environment, and all animals within recently formed groups, regardless of status, increased caloric intake and gained weight when access to a high-fat, sugary diet was provided. 3) Exposure to an acute, psychological stressor among subjects in recently formed groups markedly reduced caloric intake among high and middle ranking subjects regardless of diet availability while the lowest ranking females, who consumed fewer calories than conspecifics during control conditions, did not further reduce their caloric intake in response to the acute stressor. These findings support a role of stressor exposure in promoting excess caloric intake from palatable diets but also highlight the potential importance of stressor intensity, duration, and intermittency in shaping the bidirectional effects of stressor exposure on dietary patterns.

Table of Contents

Chapter 1: Project Justification

Introduction (1)

Homeostatic and Hedonic Regulation of Food Intake (3)

The Physiologic Stress Response and Food Intake (13)

A Nonhuman Primate Model of Psychosocial Stress (18)

Chapter 2: Antagonism of CRF Type 1 Receptors Attenuates Caloric Intake of Free-feeding Subordinate Female Rhesus Monkeys in a Rich Dietary Environment

Abstract (23)

Introduction (24)

Materials and Methods (27)

Results (30)

Discussion (32)

Conclusion (37)

Tables and Figures (39)

Chapter 3: Social Dominance Does Not Prevent Increased Caloric Intake and Weight Gain among Newly Formed Social Groups of Female Rhesus in a Rich Dietary Environment

Abstract (43)

Introduction (44)

Materials and Methods (49)

Results (55)

Discussion (63)

Conclusion (71)

Tables and Figures (73)

Chapter 4: Acute Stressor Exposure Does Not Increase Short-term Caloric Intake among Female Rhesus Monkeys with or without Access to a Palatable Diet

Abstract (93)

Introduction (94)

Materials and Methods (98)

Results (104)

Discussion (107)

Conclusion (111)

Tables and Figures (114)

Chapter 5: Summary and Conclusions

Summary of Significant Findings (120)

Strengths of Study Design (124)

Study Limitations (126)

Broader Implications of Study Findings (128)

References (132)

About this Dissertation

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School	Laney Graduate School
Department	Biological and Biomedical Sciences
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Health Sciences, Nutrition
Keyword	psychosocial stress food intake obesity
Committee Chair / Thesis Advisor	Wilson, Mark, Emory University
Committee Members	Jones, Dean P, Emory University Venkat Narayan, K.M., Emory University Pace, Thaddeus, Emory University Gillespie, Charles, Emory University Johnson, Zachary Peter, Emory University

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