Hurry! The Anabolic Window Is Soon To Close!!!

The Anabolic Window! Credit: BroScience

Hurry! You’re going to miss the anabolic window!!! The mysterious anabolic window that all bodybuilders live by. Either furiously driving home or bringing their food to the gym it seems like it’s a must; but is it? How much conclusive evidence is out there supporting this anabolic window? How long is this window really? Is it 30 minutes? 2 hours? There’s a lot of bro-science that comes into play when hypothesizing why we feel the need to give ourselves a bolus of carbohydrates and protein following a workout. There is some truth to this theory of the anabolic window. The total conclusiveness of all this and its reality still remains dubious, however.

From what I have heard by some of the “bro-science experts” in the gym is that you need to eat immediately following a work out to spike the insulin levels to achieve maximal protein-synthesis. So I went ahead and looked at some of the research papers reviewing this topic. I found some unclear evidence as to whether or not this is fully supported in practice. Essentially, the basic physiology of insulin is the limiting factor. Yes, spiking your insulin will help drive glucose into cells through the GLUT4 receptor that is also up-regulated during exercise.

Diagram of the Glut4 Receptor on Muscle

But what does it mean to spike the insulin? In a majority of the research papers, the researchers found increased in glucose utilization and decreased proteolysis in subjects who were FASTED.

However, when examining unfasted subjects the results they found were less. In reality, most people eat before they go and workout. They eat because they are hungry or because they feel they need the energy for their gym session. This is all fine and good because eating beforehand will help express the insulin-dependent GLUT4 receptors on muscle tissue; and this could have beneficial effects for exercise. But this pre-workout meal causes a spike in your insulin which can remain above baseline for as great as 5 hours after! This would make it harder to spike your insulin with a post-work out meal/nutrition as the levels are already elevated. So does this mean that you cannot attenuate post-workout proteolysis if you eat before working out? Does this mean that you shouldn’t eat before working out? No and no.

In my opinion the current data out there is too conflicting to follow one set rule. You should do what feels right for you. Yes, chronic exercise will increase the static expression of GLUT4 receptors on muscles thereby making you more insulin sensitive. This means that your muscles are going to always be primed for glucose uptake regardless of the insulin spike, in theory. This is one of the reasons why bodybuilders and resistance-trained athletes tend to get ‘hangry.’ It’s because they are already insulin sensitive from their already expressed glucose receptors on their muscles.

Our bodies are efficient and can readily adapt. I eat before and after a workout, and honestly sometimes I’ll snack during the session. I do this because I’m hungry and I’m listening to my body; threatening to pass out if I don’t feed it some blood sugar. Eat a lot. Keep feeding the machine.

This anecdote is referring solely to proteolysis/protein synthesis. It is not talking about the repletion of glycogen. That is coming up in a future article.

Citations:

Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition, 10, 5. https://doi.org/10.1186/1550-2783-10-5

Ivy, J. L. (1998). Glycogen resynthesis after exercise: effect of carbohydrate intake. International Journal of Sports Medicine, 19 Suppl 2, S142-145. https://doi.org/10.1055/s-2007-971981

Richter, E. A., Derave, W., & Wojtaszewski, J. F. P. (2001). Glucose, exercise and insulin: emerging concepts. The Journal of