We examined whether acute and/or chronic skeletal muscle anabolism is impaired with a low carbohydrate diet formulated to elicit ketosis (LCKD) versus a mixed-macronutrient Western diet (WD). Male Sprague-Dawley rats (9-10 weeks of age, 300-325 g) were provided isoenergetic amounts of a LCKD or a WD for 6 weeks. In AIM 1, basal serum and gastrocnemius assessments were performed. In AIM 2, rats were resistance-exercised for one bout and were euthanized 90-270 min following exercise for gastrocnemius analyses. In AIM 3, rats voluntarily-exercised daily using resistance-loaded running wheels, and hind limb muscles were analyzed for hypertrophy markers at the end of the 6 week protocol. In AIM 1, basal levels of gastrocnemius phosphorylated (p)-rps6, p-4EBP1 and p-AMPKα were similar between diets, although serum insulin (P<0.01), serum glucose (P<0.001), and several essential amino acid levels (P<0.05) were lower in LCKD-fed rats. In AIM 2, LCKD- and WD-fed rats exhibited increased post-exercise muscle protein synthesis (MPS) levels (P<0.0125), but no diet effect was observed (P=0.59). In AIM 3, chronically exercise-trained LCKD- and WD-fed rats presented similar increases in relative hind limb muscle masses compared to their sedentary counterparts (12-24%, p<0.05), but there was no between-diet effects. Importantly, the LCKD induced 'mild' nutritional ketosis, as the LCKD-fed rats in AIM 2 exhibited ~1.5-fold greater serum beta-hydroxybutyrate levels relative to WD-fed rats (diet effect P=0.003). This study demonstrates that the tested LCKD in rodents, while only eliciting mild nutritional ketosis, does not impair the acute or chronic skeletal muscle hypertrophic responses to resistance exercise.
- low carbohydrate diets
- muscle hypertrophy
- muscle protein synthesis
- Copyright © 2015, Journal of Applied Physiology