Food Cravings in People Engaged in Weight …

Food Cravings in People Engaged in Weight Management

Emilie Frances Smithson

Submitted in accordance with the requirements for the degree of Doctor of Clinical Psychology (D. Clin. Psychol.) The University of Leeds

Academic Unit of Psychiatry and Behavioural Sciences School of Medicine

September 2014

The candidate confirms that the work submitted is his/her own and that appropriate credit has been given where reference has been made to the work of others

This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. 1

ACKNOWLEDGEMENTS Before presenting this thesis, I would like to express my deepest and most sincere thanks to the people that gave their time and effort in supporting me through the process, and in doing so made this work possible.

Firstly, my gratitude to my supervisor Andy Hill, for his patience and guidance throughout the duration of the research, and for his calm words during moments of wild panic. Secondly, to all the participants who gave their time and contributions to the research project, and for their patience with technical glitches. Next, my thanks to Carolyn Pallister and Jacquie Lavin for their insights into all things Slimming World, and for their support in making this project possible. My gratitude to Liam Morris for his assistance providing timely weight data for the analyses. Merit also to my family and friends, for kindly helping with dry runs and proof reading, and to my parents, for getting me this far in the first place.

Here, my infinite love and appreciation for Christopher, in his understanding of me better than I could understand myself, for his patience with all my procrastinations, and for taking me on long walks in the sunshine to clear my head. Without his gentle encouragement, I would still be reorganising kitchen cupboards.

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ABSTRACT The relationship between dieting and food cravings has been studied extensively; however, due to varied methodology, questionnaire measures and construct definitions, the evidence is conflicting. The present study was conducted in order to investigate the relationship between cravings, dieting and weight loss using a craving specific measure and gathering data at two different time points during active weight management. A large national sample of individuals (N=2932) enrolled in a commercial weight loss organisation completed two questionnaires approximately seven weeks apart. Information was collected on craving experiences, mood, restraint and weight change. Cross-sectional analysis found those `dieting to lose weight' reported significantly fewer, less intense and more easily controlled food cravings than those `watching their weight'. In longitudinal analyses, there was a significant reduction in cravings that could not be accounted for by change in mood or dietary restraint. Frequency of `eating in response to food cravings' at Time 1 explained 7.1% of the variance in overall weight change, such that those more likely to eat in response to food cravings lost less weight over the period of observation. A significant positive relationship was observed between weight loss and participants' sense of control over their food cravings. Clinical implications draw attention to the contribution of momentary self-regulatory inhibition when explaining the variance in weight loss, and the reciprocal relationship between perceived control of cravings and weight regulation. The potential benefit of incorporating psychological strategies into weight-loss programmes to help support individuals struggling to cope with food cravings is discussed.

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Table of Contents ACKNOWLEDGEMENTS ......................................................................................................2 ABSTRACT .............................................................................................................................. 3 LIST OF TABLES....................................................................................................................7 LIST OF FIGURES ..................................................................................................................8 ABBREVIATIONS ..................................................................................................................9 INTRODUCTION ..................................................................................................................10 LITERATURE REVIEW .......................................................................................................11

3.1 Obesity ....................................................................................................................11 3.1.1 Social, Economic, Physical & Psychological Impact of Obesity....................11 3.1.2 Strategies to Reduce Obesity ..........................................................................12 3.1.3 Effectiveness & Efficacy of Weight-Loss Intervention Strategies .................13

3.2 Dietary Intake and Food Cravings ..........................................................................15 3.2.1 Physiological Theory of Food Cravings .........................................................16 3.2.2 Restraint Theory of Food Cravings.................................................................17

3.3 Dieting and Food Craving.......................................................................................19 3.3.1 Defining and Measuring `Cravings'................................................................19 3.3.2 Defining and Measuring `Dieting' ..................................................................22 3.3.3 Dieting and Food Cravings: A Review of the Evidence .................................24

3.4 Summary of Research .............................................................................................31 3.5 Principal Research Question ...................................................................................32

3.5.1 Hypotheses......................................................................................................32 METHOD ...............................................................................................................................34

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4.1 Design .....................................................................................................................34 4.2 Participants..............................................................................................................34 4.3 The Survey ..............................................................................................................35 4.4 Measures .................................................................................................................36

4.4.1 Demographic Information:..............................................................................36 4.4.2 Control of Eating Questionnaire ? 7 day version............................................37 4.4.3 Three-Factor Eating Questionnaire .................................................................37 4.4.4 Perceived Self-Regulatory Success of Dieting ...............................................38 4.4.5 Depression Anxiety and Stress Scale..............................................................39 4.4.5 Weight Data ....................................................................................................39 4.5 Procedure ................................................................................................................40 4.6 Data Analysis ..........................................................................................................41 RESULTS ...............................................................................................................................43 5.1 Part I: Cross sectional analysis of cravings by classification..................................43 5.1.1 Participants......................................................................................................43 5.1.2 Group Differences...........................................................................................46 5.1.3 Dietary Restraint, Perceived Success of Dieting and Mood ...........................47 5.1.4 Control of Eating Questionnaire .....................................................................47 5.2 Part II: Investigating weight change and change in craving experiences ...............51 5.2.1 Participants......................................................................................................51 5.2.2 Changes in outcome measures between time points for whole sample ..........53 5.2.3 Relationship between craving experiences and weight loss............................58 DISCUSSION .........................................................................................................................60

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6.1 Summary of Results................................................................................................60 6.1.1 Cross-sectional differences between `dieting' groups ....................................60 6.1.2 Craving change during active weight management ........................................62 6.1.3 Association of change in weight and food cravings........................................64

6.2 Theoretical & Clinical Implications........................................................................66 6.2.1 Theoretical Implications .................................................................................66 6.2.2 Clinical Implications .......................................................................................68

6.3 Study Strengths, Limitations & Research Recommendations ................................70 CONCLUSION ....................................................................................................................... 76 REFERENCES .......................................................................................................................78 APPENDICES ........................................................................................................................93

Appendix 1: Search Strategy ..............................................................................................93 Appendix 2: Notification of Ethical Approval....................................................................96 Appendix 3: Information and Consent Page .......................................................................97 Appendix 4: Measures ........................................................................................................98

a) Demographic Information...........................................................................................98 b) Control of Eating Questionnaire (7 day version)........................................................98 c) Three Factor Eating Questionnaire (Restraint sub-scale) .........................................103 d) Perceived Self-Regulatory Control of Dieting..........................................................104 e) The Depression Anxiety and Stress Scale.................................................................105 Appendix 5: Health conditions currently prescribed medication......................................107 Appendix 6: Epistemological Reflection ..........................................................................108

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LIST OF TABLES Table 1: Demographic data ........................................................................................46 Table 2:Dietary Restraint, Perceived Success of Dieting, and psychopathology ......47 Table 3: Craving Experience......................................................................................48 Table 4Frequency of Food Cravings for different food types ..................................49 Table 5: Appetite and satiety ratings..........................................................................50 Table 6: State Mood ...................................................................................................51 Table 7: Changes in psychological wellbeing for whole sample ...............................54 Table 8: Changes in craving experience for whole sample........................................55 Table 9: Changes in specific cravings for whole sample...........................................56 Table 10: Changes in appetite and satiety for whole sample .....................................57 Table 11:Changes in state mood for whole sample ...................................................57 Table 12: Associations of baseline response to craving and weight change over the study period................................................................................................................58

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LIST OF FIGURES Figure 1: Flow chart of participant retention .............................................................43 Figure 2: Geographical spread of participants ...........................................................45 Figure 3: Flow chart of participant retention .............................................................52 Figure 4: Histogram of weight (kg) at Time 1 and Time 2........................................52 Figure 5: Hypothetical model of eating and weight regulation..................................68

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