Vol 12, Issue 2

Effects of a 3-week High-Fat-Low-Carbohydrate Diet on Lipid and Glucose Profiles in 8 Experienced, Middle-age Male Runners

February 15, 2019 - By 

Authors

Eric K. O’Neal, ekoneal@crimson.ua.edu
Ashton F. Smith, University of North Alabama
Alexander J. Heatherly, Middle Tennessee State University
Lauren G. Killen, University of North Alabama
Hunter S. Waldman, Mississippi State University
Angela Hollingsworth, The University of Alabama in Huntsville
Yunsuk Koh, Baylor University
International Journal of Exercise Science 12(2): 786-799, 2019. 
DOI:10.70252/VMVW2171

Abstract

This study examined glucose and lipid marker responses following a 3-week, ad libitum low-carbohydrate-high-fat diet (LCHF; ~70% kcals from fat, <50 g/day of net carbohydrates) versus the habitual mixed macronutrient diet (HMD) of eight middle-age, trained male runners (40 ±10 years; V̇O2peak = 49 ±4 mL·kg-1·min-1). Blood was drawn at 0600 from an antecubital vein after an overnight fast under conditions of no exercise/ heat stress (NEXH; 48 h of restriction from intense exercise) or 24-h after exercise/heat stress (EXH; 60 min run in hot conditions plus 5-km time trial) for both dietary conditions. Glucose improvement during LCHF approached but did not reach statistical significance (p = 0.07). Pre-exercise triacylglycerol did not differ between treatments but decreased > 20 mg/dL (p < 0.05) for both treatments from NEXH to EXH (HMD = 42 ± 16; LCHF = 35 ± 21 mg/dL). Main effects for diet were exhibited for HDL-C during NEXH and EXH (HMD = 48 ± 10 and 50 ± 11; LCHF = 57 ± 13 and 60 ± 13 mg/dL), and LDL-C also increased (p = 0.02) by ~20 mg/dL for LCHF at both collection points resulting in ~30 mg/dL greater total cholesterol for LCHF before and 24-h after exercise (p < 0.05). A 3-week, ad libitum LCHF did not elicit significant negative cardiovascular disease risk in male runners 30-50 years of age with healthy pre-intervention lipid and glucose marker status.

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