Abstract

Purpose: The primary aim of this study was to determine the impact of various fast-interrupting shakes on markers of glycemic control including glucose, β-hydroxybutyrate (BHB), insulin, glucagon, GLP-1, and GIP. Methods: Twenty-seven adults (12 female, 15 male) completed all three conditions of this study. One condition consisted of a 38-hour water-only fast, and the other two conditions were similar but the fasts were interrupted at 24 hours by either a high carbohydrate/low fat (HC/LF) or a low carbohydrate/high fat (LC/HF) shake. Results: The water only fast resulted in 135.3% more BHB compared to the HC/LF condition (t = 7.77, p < 0.0001) and 69.6% more compared to the LC/HF condition (t = 5.12, p < 0.0001). Conversely, the LC/HF condition exhibited a 38.8% higher BHB level than the HC/LF condition (t = 2.70, p = 0.0086). Additionally, the area under the curve (AUC) for glucose was 14.2% higher in the HC/LF condition than in the water condition (t = 6.23, p < 0.0001) and 6.9% higher compared to the LC/HF condition (t = 3.14, p = 0.0024), with the LC/HF condition yielding 7.8% more glucose than the water condition (t = 3.21, p = 0.0020). At the 25-hour mark, insulin and glucose-dependent insulinotropic polypeptide (GIP) were significantly elevated in the HC/LF condition compared to the LC/HF condition (F = 3.84, p = 0.0002 and F = 2.27, p = 0.0244, respectively) and compared to the water condition (F = 7.00, p < 0.0001 and F = 9.96, p < 0.0001, respectively). Furthermore, insulin, glucagon-like peptide-1 (GLP-1), and GIP were increased in the LC/HF condition compared to the water condition at 25 hours (F = 3.19, p = 0.0016, F = 2.43, p = 0.0158, and F = 12.13, p < 0.0001, respectively). Notably, glucagon concentrations at the 25-hour mark decreased in the HC/LF group compared to the LC/HF condition (F = 3.37, p = 0.0009). However, by the 38-hour time point, no statistically significant differences were observed among the conditions for any of the analyzed hormones. Conclusions: While a LC/HF shake does not mimic a fast completely, it does preserve some of the metabolic changes including elevated BHB and glucagon, and decreased glucose and insulin compared to a HC/LF shake.

Degree

PhD

College and Department

Life Sciences; Exercise Sciences

Rights

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

Date Submitted

2023-10-04

Document Type

Dissertation

Handle

http://hdl.lib.byu.edu/1877/etd13420

Keywords

fast mimicking, ketosis, metabolic control, glucose control

Language

english

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