Abstract

Overweight and obesity has increased in the U.S. Unfortunately, this increases the risk of metabolic dysfunction, such as diabetes. Meal timing has recently shown promise as viable options to minimize the risk of overweight or obesity and metabolic dysfunction. The primary purpose of this study, therefore, was to investigate the effect of timing of energy intake on blood glucose in females with overweight or class one obesity (BMI=27-35 kg/m2). This study utilized crossover design with two conditions counterbalanced in random order. Participants completed two 2-week 1500kcal dietary interventions: 1) a big breakfast diet or BB (50% of energy intake between 7-9am, 35% of energy between 12-2pm, and ~15% of energy between 5-7pm), and 2) a big dinner diet or BD (~15% of energy intake between 7-9am, of energy between 12-2pm, and ~50% of energy between 5-7pm). There was a 2-week wash-out period between each condition. Meals were provided to participants. The primary outcome was differences in glucose over the course of each 2-week period. Glucose was determined using a continuous glucose monitor and analyzed for area under the curve (AUC) using the trapezoidal method. Other exploratory outcomes were assessed, including: fasting glucose, height, weight, body composition using dual-energy x-ray absorptiometry, physical activity and sleep using accelerometry, waist circumference, hunger using visual analog scales, sleep quality using the Pittsburg Sleep Quality Index, depression and anxiety using the Depression Anxiety and Stress Scale, eating behaviors using the Dutch Eating Behavior Questionnaire, resting heart rate using an oximeter, blood pressure using an aneroid cuff and sphygmomanometer and temperature using a temporal scan thermometer. This study was designed for proof of concept. The primary analysis showed there was no significant difference in total AUC glucose between the BB and BD conditions (F=0.14; p=0.7137). A secondary analysis indicated a significant interaction between dietary condition across the 14-day intervention (F=98.23; p<0.001) and condition x hour interaction for glucose AUC (F=32.62; p<0.0001). As expected, the BB diet had higher AUC glucose from 7am-12pm (F=15.48; p=0.001) and the BD diet has higher AUC glucose from 5pm-10pm (F=11.63; p=0.0031). Both conditions were effective to decrease weight, waist circumference, BMI, and fat free mass (p<0.05); however, the condition x time interaction was significantly more reduced for fat mass during the BB than the BD condition (F=4.37; p=0.0411). This study did not reveal a difference in total AUC glucose between the BB and BD. It was shown that the BB saw a greater rate of fat mass loss then the BD. This indicates that meal timing can provide addition benefits to the outcomes caused by a caloric deficit.

Degree

MS

College and Department

Life Sciences; Nutrition, Dietetics, and Food Science

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2023-12-13

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd13017

Keywords

glucose metabolism, caloric timing, weight loss

Language

english

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