Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- All Subjects: Ghrelin
- Creators: School of Nutrition and Health Promotion
Description
Ghrelin is an acylated peptide hormone with far reaching affects within the human body. Consisting of both central and peripheral effects, ghrelin has been the topic of research since its discovery in 1999. These effects include energy maintenance, cardiovascular health, growth hormone mediation, glucose homeostasis, muscle growth and atrophy, and bone metabolism, all of which work in concert with other well-known physiological mechanisms. With the goal to reproduce a similar study done in females in males, this study hypothesized that ghrelin would present an inverse relationship with a young healthy male population's resting metabolic rates. The study consisted of taking resting metabolic rate measurements, dual-energy X-ray absorptiometry, blood ghrelin testing, and statistical analysis of the data. The hypothesis was shown to be incorrect as the data showed a positive correlation, albeit, with very low statistical significance. Despite the data, past research has shown ghrelin plays a major role in fat gain, fat loss, and energy expenditure. Obesity is plaguing the world and becoming a major pubic health concern. It is necessary to explore causality and casual relationships in order to better understand and combat obesity. Therefore, further research is warranted into ghrelin and energy expenditure as a biomarker or novel treatment for obesity.
ContributorsLopez, Stephen Thomas (Author) / Johnston, Carol (Thesis director) / Levinson, Simin (Committee member) / School of Nutrition and Health Promotion (Contributor) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Weight cycling (WC) is characterized by repeated bouts of weight loss followed by regain. WC has been associated with a number of adverse health consequences and is a risk factor for cardiovascular disease. Body weight regulation is complex. Little is known about why women who intentionally lose weight are so likely to regain their weight back. Humans are motivated by a variety of psychological pressures as well as physiological stimuli that influence eating behaviors and weight control. One of the complex factors that has been shown to predict weight regain, in weight-reduced individuals, is hunger. Ghrelin is a known gastrointestinal hormone that rises during weight loss and is a strong trigger of hunger and increased appetite. Increased ghrelin levels have been associated with disordered eating behaviors and active weight loss. The Three Factor Eating Questionnaire (TFEQ-R18) describes elements that may affect hunger and satiety. These factors are: cognitive restraint (CR, defined as regulating food intake because of weight maintenance), uncontrolled eating (UE, defined as difficulty in regulating eating), and emotional eating (EE, refers to the tendency to eat more than needed because of mood state). Objective: The purpose of this study was to explore the associations of fasting plasma ghrelin with eating behaviors and weight cycling in overweight and obese women. Methods: This is a cross-sectional observation of women aged 20-60 years who completed a Weight and Lifestyle Inventory (WALI) and the TFEQ-R18. Women provided a 12-h fasting blood sample and plasma ghrelin was measured using a commercial radioimmunoassay (ELISA kit Cat# EZGRA-88k). Intra- and inter-assay CVs were 88.4% + 13.8% and 84.4% + 8.4% respectively. Descriptive data were computed and Pearson correlations were assessed adjusting for age and body weight (SPSS, v23). Results: A WC Index (WCI) was computed as number of WC reported x the amount of weight lost per cycle. 61 women (mean age: 39.3 + 11 yr; BMI: 31.4 + 7; WCI: 70 + 60; range = 0 to 253) completed questionnaires. Ghrelin was significantly and negatively correlated to weight (R= -0.25, P = 0.03), BMI (R= -0.32, P = .006), UE (R = -0.29, p = 0.02), and EE (R = -0.29, p = 0.04). Ghrelin was not significantly related to WCI. WCI was not significantly correlated with any TFEQ-18 subscales. Conclusion: In this observational study, lower ghrelin was associated with higher UE and EE. Thus physiological hunger sensations from ghrelin secretion, is not a likely stimulus of eating behavior in these women. There are a host of psychological triggers, such as stress, loneliness, guilt, anger etc. that may enhance eating. Future research will need to explore what psychological triggers influence eating behavior and why obese women are resistant to the powerful physiological hunger cues of ghrelin.
ContributorsHearns, Joan B. (Author) / Swan, Pamela (Thesis director) / Sweazea, Karen (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05