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.
Displaying 1 - 10 of 12
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- All Subjects: Intermittent Fasting
- All Subjects: Vegetarianism
- Creators: Johnston, Carol
Description
Dietary protein is known to increase postprandial thermogenesis more so than carbohydrates or fats, probably related to the fact that amino acids have no immediate form of storage in the body and can become toxic if not readily incorporated into body tissues or excreted. It is also well documented that subjects report greater satiety on high- versus low-protein diets and that subject compliance tends to be greater on high-protein diets, thus contributing to their popularity. What is not as well known is how a high-protein diet affects resting metabolic rate over time, and what is even less well known is if resting metabolic rate changes significantly when a person consuming an omnivorous diet suddenly adopts a vegetarian one. This pilot study sought to determine whether subjects adopting a vegetarian diet would report decreased satiety or demonstrate a decreased metabolic rate due to a change in protein intake and possible increase in carbohydrates. Further, this study sought to validate a new device called the SenseWear Armband (SWA) to determine if it might be sensitive enough to detect subtle changes in metabolic rate related to diet. Subjects were tested twice on all variables, at baseline and post-test. Independent and related samples tests revealed no significant differences between or within groups for any variable at any time point in the study. The SWA had a strong positive correlation to the Oxycon Mobile metabolic cart but due to a lack of change in metabolic rate, its sensitivity was undetermined. These data do not support the theory that adopting a vegetarian diet results in a long-term change in metabolic rate.
ContributorsMoore, Amy (Author) / Johnston, Carol (Thesis advisor) / Appel, Christy (Thesis advisor) / Gaesser, Glenn (Committee member) / Arizona State University (Publisher)
Created2012
Description
In 2002, a scientifically derived food guide pyramid for vegetarians, the Modified Food Guide for Lacto-ovo-vegetarians and Vegans was published and well received. Now that 10 years have passed, new scientific literature regarding the bioavailability of the nutrients of key concern in vegetarian diets has been published, and the graphical format of the nation's food guide has evolved from a pyramid shape into a circular plate. The objective of this research was to examine the post-2002 literature regarding the bioavailability of key nutrients in vegetarian diets; to use this information to update the recommendations made in the 2002 Modified Food Guide Pyramid for Lacto-ovo-vegetarians and Vegans; and to adapt this revised food plan to the new USDA MyPlate format. This process involved reviewing the scientific literature to determine if the DRIs for the nutrients of key concern in vegetarian diets are adequate for the vegetarian population and using this information to develop new recommendations for vegetarians if necessary, analyzing the nutrient content of representative foods in different food groups, reconfiguring the food groups so that foods with like nutrient components were grouped together, determining the number of servings of each food group required to meet vegetarians' nutrient requirements at three caloric levels, and developing sample menus. A circular plate graphic, the Vegetarian Plate, was designed to illustrate the recommendations of this updated food guide. This updated, scientifically derived food guide provides a sound base for diet planning for lacto-ovo-vegetarians and vegans. Further research is needed to assess the Vegetarian Plate's adequacy for children, pregnant and lactating women, athletes, and individuals with medical conditions or chronic diseases.
ContributorsFladell, Lauren (Author) / Johnston, Carol (Thesis advisor) / Vaughan, Linda (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2013
Description
Background. Research suggests that non-O blood types are at an increased risk of thrombosis and related health complications in cardiovascular disease (CVD). This is due in part to higher concentrations of von Willebrand factor (VWF), an important factor involved in blood clotting. Objective. The purpose of this study was to examine the effects of a vegetarian-like diet on blood coagulation and other health parameters in adults with type A blood compared to type O blood over a four week intervention. Given the lack of previous research on blood type and diet, it was hypothesized that no difference in blood coagulation would be observed. Design. This study was a randomized, parallel arm, dietary intervention using healthy, omnivorous adults with blood types A and O. A total of 39 subjects completed the study. Subjects were randomized into two groups: a vegetarian-like diet group made up of 12 type As and 12 type Os and an omnivorous control diet group made up of 11 type As and 12 type Os. At weeks 0 and 4, fasting blood was drawn and analyzed for prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand factor (VWF), total cholesterol, LDL, HDL, triglycerides, and CRP. In addition, subjects were weighed and filled out a FFQ at weeks 0 and 4. Results. After adhering to a vegetarian-like diet for four weeks, type Os had a significant increase in PT (+0.24±0.32 sec/ p=0.050), whereas type As saw no significant change. There was a trend of weight loss for type Os in the vegetarian-like diet group (-1.8±2.6 lb/ p=0.092) and significant weight loss for type As (-0.9±2.1 lb/ p=0.037). Both blood types O and A experienced significant decreases in BMI (-0.3±0.4/ p=0.092 and -0.2±0.3/ p=0.037, respectively). No change was seen in APTT, VWF, total cholesterol, LDL, HDL, triglycerides, or CRP. Conclusion. Type Os saw an increase in PT, perhaps indicating a reduction in risk of thrombosis and its related health complications. Type As were less responsive to the dietary intervention and may require more rigid dietary guidelines or a longer time on such a diet to see the benefits.
ContributorsBrown, Jennifer (Author) / Johnston, Carol (Thesis advisor) / Martin, Keith (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2013
Description
Circadian misalignments in terms of eat and sleep cycles, common occurrences among college students, are linked to adverse health outcomes. Time-restricted feeding, a form of intermittent fasting, may offer an exciting, non-pharmacologic approach to improve the health of this population by restricting eating to feeding windows that align with circadian biology. This study aims to fill a gap in the literature regarding the effect of early time-restricted feeding (eTRF) on college students, particularly in regard to diet quality, diet self-efficacy, and sleep quality. To test the hypothesis that eTRF would lead to an increase in all three variables, a 4-wk randomized-controlled, parallel arm trial was conducted. Thirty-five healthy college students were randomly assigned to one of two groups: the intervention group (TRF) was instructed to adhere to an 8-h feeding window aligned with the light cycle (9 am to 5 pm), and the control group (CON) was instructed to adhere to a 12-h feeding window typical of college students (10 am to 10pm). The eTRF diet was consumed ad libitum, and the participants were not instructed to avoid compensatory hyperphagia. The results showed a strong, reverse effect of eTRF on diet quality: fasting had a highly significant association with decreased diet quality. The results suggest that, under free-living conditions, college students practicing eTRF are more likely to compensate for prolonged fasting with unhealthy eating and snacking.
ContributorsGonzalez, Valeria Isabel (Author) / Johnston, Carol (Thesis director) / Hundley, Amanda (Committee member) / Edson College of Nursing and Health Innovation (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Intermittent Fasting (IF) is defined as a cyclical eating pattern where an individual will fast for a specific increment of time, followed by caloric intake periods. Fasting is a crucial part of our ancestors’ adaptation to the stresses of famine in order to maintain mental acuity and physical abilities during food deprivation. IF influences physiological changes such as: triggers protective metabolic pathways, increases metabolic flexibility and resilience, promotes DNA repair and autophagy, increases microbiome diversity and restores the natural cyclical fluctuations of the gut, increases BDNF expression in mood regulating neuronal circuits, and enhances synaptic plasticity of the brain. Research on the underlying causes of mood disorders has linked impairments in neuroplasticity and cellular resilience to this pathophysiology, which fasting could mitigate. Depression and anxiety are reported as the top impediments to academic performance. Thus, an easily implemented treatment such as intermittent fasting may be an option for combating impaired mental health in college students. This research study tested time restricted feeding (TRF) and its impact on mood states. It was hypothesized that: if college students follow a time restricted feeding pattern, then they will be less moody due to TRF’s effects on the metabolism, brain, and gut. The study consisted of 11 college students: 5 following a four-week adherence to TRF (8am-4pm eating window) and 6 in the control group. The POMS questionnaire was used to measure mood states. The participants height, weight, BMI, body fat %, and POMS scores were tested at the beginning and end of the 4 week intervention. The results were as follows: weight p=0.112 (statistical trend), BMI p=0.058 (nearly significant), body fat % p=0.114 (statistical trend), POMS p=0.014 (statistically significant). The data suggests that following a TRF eating pattern can decrease moodiness and improve mood states.
ContributorsFoley, Sadie Jean (Author) / Johnston, Carol (Thesis director) / Shepard, Christina (Committee member) / Department of Management and Entrepreneurship (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Oral health encompasses a wide variety of conditions with two of the primary conditions being enamel degradation and periodontal disease. These ailments are intertwined and are known to be prevented by a combination of good oral hygiene and a balanced diet. Despite this, incidence rates of oral health conditions in both high and low-and-middle income countries remain high. Periodontal disease prevention is of particular relevance due to its correlation with cardiovascular disease. One highly popular diet that could serve as an alternative strategy in combatting these oral health conditions is intermittent fasting. Intermittent fasting has shown promise in decreasing systemic inflammation and blood glucose levels, both of which are correlated with periodontal disease and enamel degradation. To explore this relationship between intermittent fasting and oral health a 9-week experimental protocol with 4 randomly established groups was completed. These groups included ad libitum high and low-fat groups, and time restricted feeding high and low-fat groups. After the 9-week protocol the mice were sacrificed, and their intact jaws and gingiva tissue were isolated. Three primary methods were used to quantify the effects of intermittent fasting on oral health: comparing the enamel density between groups, comparing the alveolar bone recession between groups, and comparing the gene expression of periodontal disease markers between groups. Body composition and fasting blood glucose levels of the mice were also quantified. We found that the fasting groups had lower average fasting blood glucose levels and maintained a more physiologically ideal body composition. Despite this, the oral health analyses did not have any consistent significant results. The results of this study suggest that despite intermittent fasting’s role in blood glucose levels and body composition regulation, it has minimal effects on enamel degradation and periodontal disease development.
ContributorsCollis, Graham (Author) / Jakiche, Michael (Co-author) / Roberts, Joseph (Thesis director) / Johnston, Carol (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2024-05
Description
Time restricted eating (TRE) is an increasingly popular diet strategy that has shown promise for weight loss and improving metabolic health. The impact of TRE on bone health has not been extensively studied, and the goal of this experiment is to provide more insight into this subject. 32 10-week old female mice were randomly assigned to 4 groups (n = 8). These included low fat diet fed ad-libitum, low fat time restricted feeding (TRF), high fat diet fed ad-libitum, and high fat TRF. The mice adhered to these diets for 9 weeks, with the TRF groups having access to food for 8 hours per day until the sacrifice. At nine weeks, the TRF mice had significantly lowered body weight, improved body composition, and a lower fasting blood glucose. The TRF groups also experienced significant improvements in the trabecular bone density of the tibia, femur, and L3 vertebral body. This was found alongside reductions in osteoclast count and activity in the TRF mice. When compared to a baseline group of 10-week old mice, it was found that the TRF group had significantly less bone loss relative to the ad-libitum fed mice. Improvements in metabolic health, gut barrier function, and inflammation may have all contributed to the observed improvements in bone health. These results reveal a promising and previously unrecognized dietary tool to improve bone health and counteract age-related bone loss.
ContributorsJakiche, Michael (Author) / Collis, Graham (Co-author) / Roberts, Joseph (Thesis director) / Johnston, Carol (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor)
Created2024-05
Description
There is a considerable amount of research stating that vegetarian diets have an alkalizing effect while the typical western diet is acid-forming. There is substantial evidence regarding the health benefits of an alkaline diet. Although vegetarian diets demonstrate the ability to foster these health benefits, many people are still not willing to adopt a completely vegetarian diet. PURPOSE: To evaluate the effect of following a vegan diet two or three days per week on acid-base balance in a healthy college student population aged 18-30. METHODS: In a one-week interventional design, 23 people were randomly assigned to follow a vegan diet 2 days per week (VEG2;n=7), 3 days per week(VEG3;n=8), or 7 days per week (VEG7;n=8). Urine pH and dietary PRAL were assessed in each group at baseline and after the one-week intervention. RESULTS: There was no significant difference in urinary pH between the three groups (p=0.12). The change in PRAL values after the dietary intervention was different between the 3 groups (p=0.03). CONCLUSION: Adherence to a vegan diet 2 or 3 days per week did not show a significant change in urinary pH or PRAL.
ContributorsCosgrove, Kelly (Author) / Johnston, Carol (Thesis advisor) / Sweazea, Karen (Committee member) / Mayol-Kreiser, Sandra (Committee member) / Arizona State University (Publisher)
Created2015
Description
ABSTRACT
Background. College students’ modifiable health behaviors, including unhealthful eating patterns, predispose them to risk for future cardiometabolic conditions.
Purpose. This novel 8-week randomized control parallel-arm study compared the effects of a daily 18-hour Time-Restricted Feeding protocol vs. an 8-hour fast on diet quality in college students. Secondary outcomes were resting morning blood pressure, biomarkers of glucose regulation, biomarkers of lipid metabolism, and anthropometric measures.
Methods. Eighteen healthy college students (age = 23 ± 4 years; BMI = 23.2 ± 2.3 kg/m2; MET = 58.8 ± 32.9 min/wk) completed this study. Participants were randomized to a daily 18-hour fasting protocol (Intervention; n = 8) or a daily 8-hour fasting protocol (Control; n = 10) for eight weeks. One ‘cheat’ day was permitted each week. Outcomes were measured at weeks 0 (baseline), 4, and 8. A non-parametric Mann Whitney U test was used to compare the week 4 change from baseline between groups. Statistical significance was set at p≤0.05.
Results. Diet quality (p = 0.030) and body weight (p = 0.016) improved from baseline to week 4 for the INV group in comparison to the CON group. The data suggest these improvements may be related to reductions in snacking frequency and increased breakfast consumption. Fasting blood glucose and hip circumference tended to improve for the INV group in comparison to the CON group (p = 0.091 and p = 0.100). However, saturated fat intake tended to increase in the INV group in comparison to the CON group (p = 0.064). Finally, there were no treatment differences between groups (p>0.05) for the 4-week change in total calories, dietary vitamin C, added sugars, resting systolic blood pressure, resting diastolic blood pressure, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), low-density lipoprotein (LDL) cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, waist circumference, or MET.
Conclusion. These data, although preliminary, suggest that the 18-hour fasting protocol was effective for improving diet quality and reducing weight in comparison to the 8-hour fasting protocol in healthy college students. Future intervention trials will need to confirm these findings and determine the long-term relevance of these improvements for health outcomes.
Background. College students’ modifiable health behaviors, including unhealthful eating patterns, predispose them to risk for future cardiometabolic conditions.
Purpose. This novel 8-week randomized control parallel-arm study compared the effects of a daily 18-hour Time-Restricted Feeding protocol vs. an 8-hour fast on diet quality in college students. Secondary outcomes were resting morning blood pressure, biomarkers of glucose regulation, biomarkers of lipid metabolism, and anthropometric measures.
Methods. Eighteen healthy college students (age = 23 ± 4 years; BMI = 23.2 ± 2.3 kg/m2; MET = 58.8 ± 32.9 min/wk) completed this study. Participants were randomized to a daily 18-hour fasting protocol (Intervention; n = 8) or a daily 8-hour fasting protocol (Control; n = 10) for eight weeks. One ‘cheat’ day was permitted each week. Outcomes were measured at weeks 0 (baseline), 4, and 8. A non-parametric Mann Whitney U test was used to compare the week 4 change from baseline between groups. Statistical significance was set at p≤0.05.
Results. Diet quality (p = 0.030) and body weight (p = 0.016) improved from baseline to week 4 for the INV group in comparison to the CON group. The data suggest these improvements may be related to reductions in snacking frequency and increased breakfast consumption. Fasting blood glucose and hip circumference tended to improve for the INV group in comparison to the CON group (p = 0.091 and p = 0.100). However, saturated fat intake tended to increase in the INV group in comparison to the CON group (p = 0.064). Finally, there were no treatment differences between groups (p>0.05) for the 4-week change in total calories, dietary vitamin C, added sugars, resting systolic blood pressure, resting diastolic blood pressure, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), low-density lipoprotein (LDL) cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, waist circumference, or MET.
Conclusion. These data, although preliminary, suggest that the 18-hour fasting protocol was effective for improving diet quality and reducing weight in comparison to the 8-hour fasting protocol in healthy college students. Future intervention trials will need to confirm these findings and determine the long-term relevance of these improvements for health outcomes.
ContributorsMayra, Selicia (Author) / Johnston, Carol (Thesis advisor) / Sears, Dorothy (Committee member) / Swan, Pamela (Committee member) / Sweazea, Karen (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Arizona State University (Publisher)
Created2020
Description
The popularity of intermittent fasting has grown in recent years and is a commonly discussed diet topic on the internet and social media. Time-restricted feeding (TRF) is one particular intermittent fasting regime that allows participants to pick windows of time per day in which they can eat or fast. While current randomized controlled trials show positive effects of TRF on weight loss, body composition, glucose, insulin, and blood pressure, there is a gap in the literature of the its effect on cognition although animal studies suggest a positive effect. The purpose of this 8-week randomized controlled trial was to investigate the effect of 18-hour time-restricted feeding on healthy, Arizona State university students. Students (n= 29) were recruited by the research team and were randomized to either an 18-hour intervention (INV) group or an 8-hour control (CON) group. INV participants were instructed to consume food within the first hour of waking and cease their eating period after 6 hours to begin their 18-hour fast. Participants were not given any other dietary restrictions and were allowed to eat ad libitum during their eating periods. Cognitive tests (Stroop Test and Trail Making Test) and blood draws were taken at baseline, week 4, and week 8. The present study demonstrated high attrition, with 7 participants dropping out of the study after their baseline visit. Interruption of the COVID-19 pandemic also impacted the data analysis, with the removal of week 8 data. Despite limitations, statistically significant differences between the INV group and CON group were seen in the Trail Making Test B at week 4 (p= 0.031). Statistically significant differences were not seen in any of the other cognitive outcomes measured (Stroop Test, Trail Making Test A, serum BDNF, serum ketones). However, a significant inverse relationship was seen between serum ketones and Trail Making Test B. In conclusion, this study suggests that TRF may have a favorable effect on cognitive acuity among university students.
ContributorsKravat, Natalie (Author) / Johnston, Carol (Thesis advisor) / Gu, Haiwei (Committee member) / Sears, Dorothy (Committee member) / Arizona State University (Publisher)
Created2021