It is generally accepted that exercise can improve blood glucose control and enhance insulin sensitivity. Several physiological processes may be responsible for these improvements, including the following:
- Adaptations in muscle insulin signaling[1]
- Glucose transporter type four (GLUT-4)[2] protein expression, content, and action
- Enhanced intramyocellular oxidative enzyme capacity[3]
- Increased muscle capillary density.[4]
However, it is not entirely clear whether exercising in the fasted state may be better than exercising in the fed state. Based on the available scientific evidence, it seems that being physically active and losing weight (through a hypocaloric diet) are the most important factors[5] for improving glycemic control and insulin sensitivity, while performing exercise in a fasted vs. fed state plays a minor role at most. However, the research comparing the effects of fed vs. fasted exercise on glycemic control and insulin sensitivity is still in its infancy, so it’s probably best to wait until there is more research before drawing definitive conclusions.
References
- ^Holten MK, Zacho M, Gaster M, Juel C, Wojtaszewski JF, Dela FStrength training increases insulin-mediated glucose uptake, GLUT4 content, and insulin signaling in skeletal muscle in patients with type 2 diabetesDiabetes.(2004 Feb)
- ^Richter EA, Hargreaves MExercise, GLUT4, and skeletal muscle glucose uptakePhysiol Rev.(2013 Jul)
- ^Holloszy JO, Coyle EFAdaptations of skeletal muscle to endurance exercise and their metabolic consequencesJ Appl Physiol Respir Environ Exerc Physiol.(1984 Apr)
- ^Prior SJ, Goldberg AP, Ortmeyer HK, Chin ER, Chen D, Blumenthal JB, Ryan ASIncreased Skeletal Muscle Capillarization Independently Enhances Insulin Sensitivity in Older Adults After Exercise Training and DetrainingDiabetes.(2015 Oct)
- ^Clamp LD, Hume DJ, Lambert EV, Kroff JEnhanced insulin sensitivity in successful, long-term weight loss maintainers compared with matched controls with no weight loss historyNutr Diabetes.(2017 Jun 19)