New study shows that consuming pre-exercise breakfast lowers insulin levels at subsequent meals.
Diet and exercise are arguably the most heavily discussed topics when it comes to diabetes, and, more specifically, patients with type 2 diabetes. Exercise is known to play an important role in the removal of glucose from the bloodstream into skeletal muscle where it can be utilized as energy, and has thus been encouraged in many patients with diabetes looking to enhance their glycemic control.
In a new study published in the American Journal of Physiology-Endocrinology and Metabolism, investigators sought to take on a new angle in regards to diet and exercise associated with blood sugar levels. Investigators of the study postulated that the majority of studies done on glycemic response in relation to exercise are not representative of daily living in the mainstream population. The majority of exams and studies done, they attest, are performed when patients are in the fasted state rather than in the postprandial state, which is how most people in developed countries spend their time. The aim of this study, therefore, was to examine postprandial plasma glucose levels after three different states: breakfast-rest, breakfast-exercise, and overnight-fasted exercise.
A randomized cross-over design was used to evaluate 12 men who self-reported to regularly participate in at least 30 minutes of exercise, three days per week. Participants with a history of metabolic disease or any other health condition that may have put the participant at risk were excluded from the study results.
Study participants refrained from taxing physical activity and consuming both alcohol and caffeine for 24 hours prior to onset of the study. Fasting began 12 hours before the testing period where only water was consumed. In the breakfast-exercise and breakfast-rest state, participants consumed an oatmeal and milk breakfast (431 kcal), whereas in the overnight-fasted exercise state, no food was consumed. In the breakfast-exercise and overnight-fasted exercise state, participants engaged in 60 minutes of cycling while in the breakfast-rest state, no exercise was done during this period.
Expired gas samples and blood samples were collected at baseline and throughout the tests, as well as a 2-hour oral glucose tolerance test (2-h OGTT) with 73g of glucose. Muscle samples were also collected both at baseline and post-exercise or rest.
Statistical analysis was performed using ANOVA tests to determine the differences between baseline and summary measurements.
Results were shown through both plasma glucose disappearance rate and plasma glucose appearance rate and compared between states. Investigators found that consuming breakfast prior to exercise led to an increased rate of glucose disappearance during and after exercise compared to the extended overnight fasting state. They also examined plasma insulin concentrations and found that insulin levels were lower in participants who consumed breakfast prior to exercise than those who fasted.
These results allowed investigators to conclude that consuming a breakfast prior to exercise does in fact increase the plasma glucose expulsion during subsequent meals consumed after exercise, despite lower plasma levels of insulin. They conferred that consuming breakfast both improved glucose tolerance as well as insulin sensitivity after subsequent meals, and that this may be the first study to determine these results.
Glycemic management can be labeled as the most important factor when it comes to preventing complications associated with diabetes. The results from this trial are not only compelling to scientists in the diabetes community, they could become a framework for a new set of guidelines when it comes to diet and exercise in patients with diabetes.
- Rates of plasma glucose disposal into skeletal muscle post-exercise are higher in patients who consume breakfast prior to exercise than those who fasted.
- Pre-exercise consumption of breakfast lowers insulin levels at subsequent meals following exercise.
- Tests performed in the fasted state cannot be inferred to the fed state, as this study showed that glycemic response in each state varies significantly.
- Further studies are needed employing larger population size along with both sexes to solidify claims made in this study.
Edinburgh, R. M., Hengist, A., Smith, H. A., Travers, R. L., Koumanov, F., Betts, J. A., Gonzalez, J. T. (2018). Pre-Exercise Breakfast Ingestion versus Extended Overnight Fasting Increases Postprandial Glucose Flux after Exercise in Healthy Men. American Journal of Physiology-Endocrinology and Metabolism. doi:10.1152/ajpendo.00163.2018
Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy
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