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- Genre: Masters Thesis
Description
Obesity prevalence is high in the United States, in part due to increased fat storage following consumption of high fat/carbohydrate (sugar) foods. Following a meal, carbohydrate stimulates its own oxidation, while simultaneously suppressing fat oxidation, ultimately leading to fat storage. Aerobic exercise preceding a meal increases fat oxidation in the postprandial period, which may reduce fat storage. The ideal exercise prescription for optimal postprandial fat oxidation is unknown. The effect of low and moderate intensity continuous exercise (MIE) has been studied extensively, while the effects of high-intensity interval exercise (HIIE) on post-prandial substrate oxidation has not been examined. The purpose of this study was to compare the effects of MIE and HIIE on postprandial substrate oxidation after consumption of an isocaloric meal (2 glazed donuts; 520 kcal) in healthy adults. Ten subjects (8 males, 2 females; age=24yr, BMI=24 kg/m2) completed three conditions in random order: 1) no exercise control; 2) MIE: cycling at 60-75%HRmax; 3) HIIE: cycling at 90-95%HRmax. The duration of each exercise bout was sufficient to expend approximately 520 kcal, the energy equivalent of the donuts, which were consumed 1 hour post-exercise. Immediately after consuming the donuts, pulmonary ventilation and gas exchange were measured breath-by-breath continuously and recorded (min-by-min) for 5 hours. Repeated measures analysis of covariance was used to compare the mean differences in outcome variables accounting for gender. Absolute postprandial fat oxidation (g/5 hours) was 17.3±5.4, 27.1±9.6 and 23±1.2 for control, MIE and HIIE trials respectively, with the postprandial fat oxidation significantly greater for the two exercise conditions compared to control. Relative to baseline values, both exercise conditions resulted in cumulative net postprandial fat oxidation significantly greater than control (control = -1.79±3.99g; MIE = 11.51±8.41g, HIIE= 9.51±5.20g). Therefore, results indicate that exercise most certainly increases postprandial fat oxidation, and that exercise type, either MIE or HIIE, is not as important as total energy expended. The fact that exercise of ~1 hour was required to oxidize the amount of fat in two donuts, that required only a few minutes to consume, highlights the challenges of using exercise for weight control in an obesogenic environment.
ContributorsFleming, Jacob Michael (Author) / Johnston, Carol S (Thesis advisor) / Gaesser, Glenn A (Committee member) / Grant, Shauna (Committee member) / Arizona State University (Publisher)
Created2018
Description
Background: College students face a particularly high prevalence of body dissatisfaction and weight instability increasing the risk of being unhappy and having a poor quality of life. Time-restricted feeding, a type of intermittent fasting, has gained popularity recently for sustainable weight loss without the characteristic dietary restrictions of most fad diets. A limited number of randomized control trials have looked at the effects of time-restricted feeding in humans, but none have looked at how this dietary regimen impacts happiness and quality of life. Objective: The goal was to examine the effects of an 18-hour daily fasting regimen compared to an 8-hour daily fasting regimen on happiness and quality of life in college students in Arizona.
Methods: Participants included 29 healthy, non-smoking, non-vaping students attending college in Arizona between October 2020 to March 2021. Of the 16 participants allocated to the time-restricted feeding intervention, 8 completed the trial. Of the 13 participants allocated to the control group, 10 completed the trial. The eating window began within one hour of waking up with a 6-hour eating window for the intervention group and 16-hour window for the control group. They could do one cheat day per week. No dietary restrictions were enforced. Participants completed the Oxford Happiness Questionnaire and the WHOQOL-BREF quality of life questionnaire at baseline, week 4, and week 8. Week 8 data were not reported due to data collection changes and cancellations related to the new safety protocols for the COVID-19 pandemic.
Results: Quality of life related to social relationships improved significantly in the intervention group (p=0.026). There was a trend favoring the intervention group as well showing a possible improvement in happiness related to perceived energy levels (p=0.088). No other significant data were reported.
Conclusion: Adherence to an 18-hour time-restricted feeding regimen for 8 weeks may improve quality of life related to social relationships in college students in Arizona. The results of this trial do not suggest a significant impact on overall quality of life or happiness in this population.
ContributorsDe León, Anateresa (Author) / Johnston, Carol (Thesis advisor) / Shepard, Christina (Committee member) / Grant, Shauna (Committee member) / Arizona State University (Publisher)
Created2021
Description
Fish oil has been extensively researched for its protective effects on cognition. More recently, anthocyanins have also gained the attention of the medical community for their potential cognitive benefits. Maqui berries are one of the richest sources of anthocyanins known to science. While there are many randomized controlled trials (RCT) investigating the effects of fish oil and/or anthocyanins on cognition in various populations, there are no RCT that exclusively investigate the cognitive effects of these compounds in adults with Type 2 Diabetes (DM2). The purpose of this double-blinded, placebo-controlled RCT was to investigate the cognitive effects of maqui berry extract and fish oil supplements in adults with DM2 over the course of eight weeks. Adults with DM2 (n=29) were recruited by the researchers and randomized to either Group A or Group B. Because the study is ongoing, it is unknown which group received the intervention. The study used the Stroop Test and Trail Making Test (TMT) to measure cognition at baseline, 4 weeks, and 8 weeks. Anthropometrics, blood glucose, and hemoglobin A1C were also taken at these time points. Sixteen female participants were included in the final analysis. Neither group showed significant improvements in the cognitive tests. However, in Group A, the effect sizes were large for the change in Trail-Making Test A (0.167), Trail Making Test B (0.261), and Trail Making Test B minus A (0.296) scores. In Group A, the change in Trail Making Test B minus A scores between baseline and week 4, and between baseline and week 8 was significant (p=0.053) and produced a large effect size (0.258). The results suggest that fish oil and maqui berry extract may improve cognition in adults with DM2, but further studies with larger sample sizes are needed.
ContributorsDeimeke, Allyson (Author) / Johnston, Carol (Thesis advisor) / Grant, Shauna (Committee member) / Sweazea, Karen (Committee member) / Arizona State University (Publisher)
Created2023
Description
The medicinal use of vinegar dates to ancient times, and empirical evidence has mounted over the past several decades supporting health benefits from vinegar ingestion, including reductions in blood glucose, blood pressure, and blood cholesterol. Additionally, although clinical trial data are mixed, there are several reports demonstrating reductions in body mass and fat mass with daily vinegar ingestion. This blinded, randomized placebo-controlled trial examined the impact of daily vinegar ingestion on anthropometric measures in healthy young adults recruited from a campus population. Participants (n=28; aged 25.8±7.0 y; body mass index [BMI] > 23 kg/m2) were stratified by age, sex, and BMI and randomly assigned to the liquid [VIN] or pill [CON] groups. VIN participants diluted 2 tablespoons of red wine vinegar (750 mg acetic acid; Pompeian Inc.) in 8-12 ounces of water to drink with food at mealtime twice daily. CON participants consumed 1 vinegar pill daily (22.5 mg acetic acid; Spring Valley). All participants provided written consent for this IRB approved trial. The study lasted four weeks, and anthropometric measurements were conducted in a fasted state at weeks 0 and 4. Study adherence varied slightly (90±17% and 100±14% for VIN and CON respectively, p=0.029); hence, adherence was controlled for in all analyses. Changes in BMI (-0.1±0.5 and +0.1±0.3 kg/m2, p=0.127) and body weight (-0.3±1.4 and +0.1±1.1 kg, p=0.158) did not differ significantly between VIN and CON groups, respectively. However, both waist circumference and percent body fat were reduced significantly for VIN participants in comparison to CON participants (-0.5±1.3 vs. +0.6±2.4 cm [p=0.026]and -0.4±0.7 vs. +0.3±1.0% [p=0.045]. Although the observed differences between groups are modest, the study was short in duration and this protocol did not apply energy restriction or exercise interventions, suggesting a possible benefit of vinegar ingestion on adiposity.
ContributorsMeyer, Lexie Rae (Author) / Johnston, Carol (Thesis advisor) / Alexon, Christy (Committee member) / Grant, Shauna (Committee member) / Arizona State University (Publisher)
Created2024
Description
Grains are a major dietary staple in many cultures and countries. Corn can be consumed as either a fruit, vegetable, or grain. In the case of the Corn and Heart Health Study (CHS), the effect of corn flour was examined. The study used three varieties of corn flour (whole grain, refined, and a refined plus bran blend), provided by the North American Millers Association (NAMA), to examine the effectiveness of corn flour on lowering low-density lipoprotein (LDL) cholesterol as well as its effects on the diversity of the gut microbiome. The objective of this analysis was to determine the magnitude of change between pre- and post- intervention serum blood samples and the changes in alpha (within-sample) diversity in the gut microbiome. The study utilized a randomized-single blinded, crossover model. The study was 16 weeks long, with three 4-week long treatment periods with two-week washout periods in between. During each treatment period blood samples, stool samples, a diet record, and questionnaires were collected from participants. Two blood samples were collected at the beginning and end of each treatment period to account for potential day to day changes on LDL cholesterol. For the purpose of this study, the results of blood and fecal analysis were used to determine the effectiveness of the intervention. Fecal analysis using the Shannon Index showed that there was no significant difference in the within-sample microbiome diversity by corn flour type (H=2.86, p=0.72). Pre-treatment plasma LDL levels were subtracted from post-treatment levels and analyzed using a general linear model that controlled for sequence, period and a nested (ID[sequence]) variable to account for the within-person crossover design. This showed that the bran-enriched flour had the highest mean reduction in LDL cholesterol while the refined and whole grain flour resulted in increases in LDL cholesterol. The change in LDL cholesterol for bran-enriched flour was significantly different from the refined flour (Mean Difference of -14.97 mg/dL; P=.041). The results of this study indicate that refined corn flour enriched with bran could be a recommended addition to the diet to prevent cardiovascular disease and reduce LDL cholesterol in individuals who are at low risk.
ContributorsHarris, Michelle Lynn (Author) / Whisner, Corrie (Thesis advisor) / Grant, Shauna (Committee member) / Mayol-Kreiser, Sandra (Committee member) / Arizona State University (Publisher)
Created2024