Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
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- Creators: School of Nutrition and Health Promotion
Description
Obesity is becoming more prevalent in the United States and is a result of a several of factors, including an individual's genetics, environment, and societal influences. Of the most important, however, when managing weight is the balance between energy expenditure and energy intake. One's total energy expenditure is constituted of four main components: resting metabolic rate (RMR), thermic effect of food, non-exercise thermogenesis, and exercise thermogenesis. The most prominent of these is RMR, which accounts for about 60-70% of an individual's total energy expenditure.
Differences in RMR amongst individuals is dependent on a multitude of variables including height, adiposity, age, body mass, training status, and of most importance, fat-free mass (FFM). Research shows that the greater the body size, the greater the RMR. This positive association between height and body mass with RMR is attributed to more massive organ systems needed in order to meet the greater metabolic demands of a bigger individual. Research also supports that age is negatively associated with RMR. This is mostly due to sarcopenia, or the loss of muscle mass. The most important determinant of RMR, however, is FFM. Unlike body mass, FFM only accounts for metabolically active tissues including muscle, bone, blood, and all organs. Fat-free mass has been reported to account for up to 80% of the variance in RMR. Resistance training is shown to increase FFM, which results in increases in RMR. However, there are several elements to a successful, progressive resistance training protocols that result in increases in muscular strength and hypertrophy. Strength and hypertrophy gains result in a greater oxidative capacity of muscle, and consequentially a greater RMR. The most influential factor in muscular strength and hypertrophic resistance training is intensity. Moderate intensity programs are recommended for the nonathletic adult population for safety purposes. An intensity 4 of about 80% 1 RM is appropriate for increases in FFM. Training protocols lasting at least three months and that incorporate whole-body exercises have the greatest effects on FFM and RMR. Most studies show that increases in FFM of 1-2 kg are necessary increase RMR by about 3-8%. Interestingly, RT can produce similar increases in RMR and FFM in obese and overweight populations in leaner individuals. Implementing resistance training has been shown to be an effective method in managing weight and increasing both RMR and FFM.
Differences in RMR amongst individuals is dependent on a multitude of variables including height, adiposity, age, body mass, training status, and of most importance, fat-free mass (FFM). Research shows that the greater the body size, the greater the RMR. This positive association between height and body mass with RMR is attributed to more massive organ systems needed in order to meet the greater metabolic demands of a bigger individual. Research also supports that age is negatively associated with RMR. This is mostly due to sarcopenia, or the loss of muscle mass. The most important determinant of RMR, however, is FFM. Unlike body mass, FFM only accounts for metabolically active tissues including muscle, bone, blood, and all organs. Fat-free mass has been reported to account for up to 80% of the variance in RMR. Resistance training is shown to increase FFM, which results in increases in RMR. However, there are several elements to a successful, progressive resistance training protocols that result in increases in muscular strength and hypertrophy. Strength and hypertrophy gains result in a greater oxidative capacity of muscle, and consequentially a greater RMR. The most influential factor in muscular strength and hypertrophic resistance training is intensity. Moderate intensity programs are recommended for the nonathletic adult population for safety purposes. An intensity 4 of about 80% 1 RM is appropriate for increases in FFM. Training protocols lasting at least three months and that incorporate whole-body exercises have the greatest effects on FFM and RMR. Most studies show that increases in FFM of 1-2 kg are necessary increase RMR by about 3-8%. Interestingly, RT can produce similar increases in RMR and FFM in obese and overweight populations in leaner individuals. Implementing resistance training has been shown to be an effective method in managing weight and increasing both RMR and FFM.
ContributorsMccreery, Lillianne Marie (Author) / Swan, Pamela (Thesis director) / Nolan, Nicole (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
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