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The Ketogenic Diet Alters Endocrine Regulation of Energy Metabolism in Ultra‐Endurance Athletes
Author(s) -
Miller Vincent J,
Hyde Parker N,
Dickerson Ryan,
LaFountain Richard A,
Maresh Carl M,
Kraemer William J,
Volek Jeff S
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1036.3
Subject(s) - medicine , endocrinology , ketogenic diet , glucagon , leptin , carbohydrate metabolism , carbohydrate , lipolysis , glycogen , insulin , chemistry , obesity , adipose tissue , psychiatry , epilepsy
Purpose The ketogenic diet induces a profound shift in energy metabolism from carbohydrate oxidation towards fat oxidation, both at rest and during exercise. We compared endocrine regulators of energy metabolism in keto‐adapted and non‐keto‐adapted ultra‐endurance athletes before, during, and after aerobic exercise to better understand the role of endocrine function in adaptation to a ketogenic diet (keto‐adaptation). Methods Twenty elite ultra‐endurance athletes (male, age 33.5 ± 6.4 yr, BMI 22.1 ± 1.5 kg/m 2 , VO 2 max 64.5 ± 4.9 mL/kg/min) who habitually consumed a high‐carbohydrate (HC, 59:14:25 % carbohydrate:protein:fat) or very‐low carbohydrate (LC, 10:19:70) diet for at least 6 months ran on a treadmill for 180 min at 64% of VO 2 max. Glucagon, cortisol, and leptin were measured from serum collected before exercise (BL); 60 and 120 min after initiation of exercise (RUN60, RUN120); and 0, 60, and 120 min after completion of exercise (IP, P60, P120). After BL and IP, participants consumed a shake with macronutrient ratios similar to their habitual diet (5 kcal/kg body mass, HC: 50:36:14, LC: 5:81:14 % carbohydrate:protein:fat). Glucagon, cortisol, and leptin were further analyzed for correlations with non‐esterified fatty acids (NEFA), glycerol, β‐hydroxybutyrate, total ketones, insulin, glucose, and muscle glycogen. Results Glucagon increased with exercise (p<0.0001) and was significantly higher in keto‐adapted athletes at all time points except IP and P120 (p<0.05). Cortisol also increased with exercise (p<0.0001) and was significantly higher in keto‐adapted athletes at RUN60 (p<0.05). Leptin decreased with exercise (p<0.0001), but without any significant effect of diet. Glucagon and, to a lesser extent, cortisol positively correlated with markers of increased fat oxidation (β‐hydroxybutyrate, total ketones, NEFA, and glycerol, p<0.05) and negatively correlated with markers of increased carbohydrate metabolism (glucose, insulin, and lactate, p<0.05). Glucagon's correlations with β‐hydroxybutyrate and total ketones were persistent, occurring at all time points except BL (p<0.01). Glucagon and cortisol also positively correlated with each other at P120 (p<0.005). Muscle glycogen content negatively correlated with glucagon at IP (p<0.05) and positively correlated with leptin at P120 (p<0.05). Conclusion In elite ultra‐endurance athletes, a long‐term ketogenic diet is associated with higher glucagon levels before, during, and after aerobic exercise. This is in conjunction with a more than two‐fold higher rate of peak fat oxidation, indicating glucagon may have an important role in keto‐adaptation. The similar but less persistent patterns of cortisol suggest these two hormones may contribute to keto‐adaptation in a coordinated manner. Support or Funding Information Support for this work was provided by Quest Nutrition and The Robert C. and Veronica Atkins Foundation.