This study examined glucose and lipid marker responses following a 3-week, ad libitum low-carbohydrate-high-fat diet (LCHF; ~70% kcals from fat, /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.
International Journal of Exercise Science
O'Neal, E. K., Smith, A., Heatherly, A., Killen, L., Waldman, H., Hollingsworth, A., & Koh, Y. (2019). Effects of a 3-Week High-Fat-Low-Carbohydrate Diet on Lipid and Glucose Profiles in 8 Experienced Middle-Age Male Runners.. International Journal of Exercise Science, 12 (2), 786-799. Retrieved from https://ir.una.edu/kin_facpub/28