Metabolic aspects of low carbohydrate diets and exercise

Abstract

Following a low carbohydrate diet, there is a shift towards more fat and less carbohydrate oxidation to provide energy to skeletal muscle, both at rest and during exercise. This review summarizes recent work on human skeletal muscle carbohydrate and fat metabolic adaptations to a low carbohydrate diet, focusing mainly on pyruvate dehydrogenase and pyruvate dehydrogenase kinase, and how these changes relate to the capacity for carbohydrate oxidation during exercise.

Figure 1

Activation of pyruvate dehydrogenase enzyme complex control by a phosphorylation and dephosphorylation cycle.

Figure 2

Skeletal muscle pyruvate dehydrogenase in its active form (PDHa) at rest and during exercise in low carbohydrate (LCD) and high carbohydrate (HCD) diets. * denotes significance from LCD. Adapted from Putman et al. [11].

Figure 3

Pyruvate dehydrogenase kinase (PDK) activity during six days of a LCD. ^a Significantly different from day 0. ^b Significantly different from day 1. Adapted from Peters et al. [12,13].

Figure 4

Pyruvate dehydrogenase kinase (PDK) activity before and after three days of a LCD with and without n3 fatty acids. ^a Significantly different from pre diet. ^b Significantly different from post LCD diet. Adapted from Turvey et al. [21].