Document Type

Article

Publication Title

International Journal of Exercise Science

Abstract

This study examined glucose and lipid marker responses following a three-week, ad libitum low-carbohydrate high-fat diet (LCHF; approximately 70 percent of total calories from fat, less than 50 grams per day of net carbohydrates) versus the habitual mixed macronutrient diet (HMD) of eight middle-aged, trained male runners (40 plus or minus 10 years; VO2 peak = 49 plus or minus 4 milliliters per kilogram per minute). Blood was drawn at 0600 from an antecubital vein after an overnight fast under conditions of no exercise or heat stress (NEXH; 48 hours of restriction from intense exercise) or 24 hours after exercise and heat stress (EXH; a 60-minute run in hot conditions plus a 5-kilometer 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 more than 20 milligrams per deciliter (p < 0.05) for both treatments from NEXH to EXH (HMD = 42 plus or minus 16; LCHF = 35 plus or minus 21 milligrams per deciliter). Main effects for diet were exhibited for HDL-C during NEXH and EXH (HMD = 48 plus or minus 10 and 50 plus or minus 11; LCHF = 57 plus or minus 13 and 60 plus or minus 13 milligrams per deciliter), and LDL-C also increased (p = 0.02) by approximately 20 milligrams per deciliter for LCHF at both collection points, resulting in approximately 30 milligrams per deciliter greater total cholesterol for LCHF before and 24 hours after exercise (p < 0.05). A three-week, ad libitum LCHF did not elicit significant negative cardiovascular disease risk in male runners 30 to 50 years of age with healthy pre-intervention lipid and glucose marker status.

First Page

786

Last Page

799

Publication Date

2019

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