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The impact of time-restricted eating on circulating factors, insulin sensitivity and circadian rhythms

dc.contributor.authorKennedy, Devin, author
dc.contributor.authorBroussard, Josiane, advisor
dc.contributor.authorBraun, Barry, committee member
dc.contributor.authorStephens, Jaclyn, committee member
dc.description.abstractPurpose: Obesity has been steadily increasing over several decades. In 2008, prevalence rates of obesity were reported at over 300 million people, defined as a body mass index of >30kg/m2. For years, scientists have tried to find "solutions" to obesity. While obesity prevention measures taken in childhood might result in decreased adulthood obesity, childhood prevention measures are not common, and obesity is often a health issue in adulthood. Negative energy balance and caloric restriction is most effective for reducing body weight, and studies have reported beneficial effects such as reduced fasting glucose and insulin, reductions in body weight [1], significantly higher insulin sensitivity, significantly lower BMI [2], reduced β-cell sensitivity [3], and reduced fasting glycemia and fasting insulinemia [4]; however, long-term adherence to caloric restriction is low. Certain fasting practices are emerging as promising possible solutions to help combat obesity. Fasting practices have resulted in improvements in cardiometabolic health including but not limited to protection from obesity [5], improved LDL and HDL cholesterol, reduced HbA1c and c-reactive proteins, [6], cell proliferation, and body weight [7]. Intermittent fasting is one method by which an individual can reduce body weight but also improve numerous cardiometabolic factors. However, research exploring intermittent fasting (IF), specifically time-restricted eating (TRE), as a method of improving cardiometabolic health is limited. Circadian rhythms might be the reason that aligning feeding windows to earlier in the day is showing these benefits. Currently, a gap in the knowledge exists as to whether circadian rhythms play a role in contributing to the metabolic benefits that are conferred by TRE, or if the timing of the food intake/duration is what results in the benefits. Therefore, our objective was to examine the effects of TRE on 24-hour glucose homeostasis and nighttime patterns of circulating factors (glucose, insulin, free fatty acids, triglycerides, and glycerol) as well as insulin sensitivity and the central circadian clock. Methods and results: This study employed a consecutive design. Eight healthy adults (6F; 27±4 y; 22.6±2.1 kg/m2; mean ± SD) completed a 2-week protocol. During Week 1 participants were instructed to consume their daily calories over a 13h period (control condition). In Week 2, participants were instructed to consume their daily calories over an 8h period (TRE condition). Specified mealtimes were pre-determined based on the habitual sleep and wake time for each individual participant. At the end of each week, participants were admitted to the Sleep and Metabolism Laboratory for an overnight stay that involved hourly blood samples. Plasma samples were analyzed for glucose, insulin, free fatty acids (FFA), lactate, triglycerides, and glycerol. The plasma analyses indicated that TRE decreased glucose variability during sleep (p=0.03), reduced nighttime insulin concentrations (p=0.005), increased nighttime FFA levels (p=0.04), increased nighttime triglycerides (p=0.006) and increased nighttime glycerol (p=0.02). TRE did not impact glucose variability during wakefulness (p = 0.49), nighttime glucose (p = 0.39), insulin sensitivity (MATSUDA-ISI, p = 0.38), or central circadian rhythms. Conclusion: The observed changes in nighttime glucose variability and insulin levels could represent mechanisms by which TRE can improve metabolic homeostasis in healthy lean individuals. Future studies are warranted to determine whether TRE can improve metabolic homeostasis in people at risk for diabetes such as people with overweight and obesity, and impaired glucose tolerance.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.publisherColorado State University. Libraries
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dc.subjectinsulin sensitivity
dc.subjectnighttime factors
dc.subjecttime-restricted eating
dc.subjectintermittent fasting
dc.subjectcircadian rhythms
dc.subjectnocturnal factors
dc.titleThe impact of time-restricted eating on circulating factors, insulin sensitivity and circadian rhythms
dcterms.rights.dplaThis Item is protected by copyright and/or related rights ( You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). and Exercise Science State University of Science (M.S.)


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