Settle in, this is a long one…
Well, finding NIMGU doesn’t sound as funny… Fact is I wanted to know a little more about Noninsulin Mediated Glucose Uptake so I did a search and found many useless animal related and diabetic related scientific articles that really didn’t read as being accessible to anyone. I am sure most people know they should eat within an hour after workouts, I just don’t think many people know why or why it can be a real benefit to staving off any carb related guilt or cravings you may have. So here, in my own words, are the basics. Please also note I am not a scientist, nor certified nutritionist (thank God) but I know how to find what I need to know.
Your body stores energy in it’s muscles in order to fuel them for the work they do. Any additional calories that are not able to be stored in the muscles or liver are then stored for long term use as body fat. I think everyone is on side so far. When you exercise, your body uses the muscle glycogen stores and the liver glycogen stores and once those stores are gone, you hit the wall, a term that is used a lot by people who aren’t really sure what it means. Hitting the wall, or bonking, isn’t about your ability to try, or your ability to push through a pain barrier. It is a technical term to describe the point at which your glycogen stores are gone. In order to replenish these glycogen stores your body requires calories in the form of food which it can break down into glucose and form glycogen. What’s the difference between glucose and glycogen? Easy, glucose is a simple form of sugar that can be combined with other elements to form glycogen for storage. It is important to note here that the fuel burned for energy is glucose, the glycogen is actually converted before use by the body.
During the work day, you are sitting at your desk burning calories slowly, maybe out cutting the grass or walking the stroller around the mall with the moms group and your are taking in calories for lunch, mid morning coffee break or whatever. What happens to this food? Normally, you take in calories and the body converts the caloric energy into glucose which then causes a rise in blood sugar levels and illicits an insulin response. The body’s method of converting different types of foods is where the problems start.
Pause for a second and note that this is a simplistic version of what happens in order to illustrate a point. Some of the mechanisms are too micro to be discussed here.
Let’s say that you eat a danish. Lots of carbohydrate and lots of sugar. Your body senses a rapid rise in blood sugar levels and secretes insulin in order to convert the glucose into bodyfat for storage. This is how your body was designed to work, take excess blood sugar and store it for later use (based on the assumption that humans would be out hunting for food, not hunting donuts). The insulin in your body is helping you to have energy to ride out the lean times when calories are harder to come by. The opposite hormone is glucagon which is secreted by the pancreas in order to tell the liver to convert the glycogen to glucose to raise the blood sugar levels which is critical during exercise when you need glucose in the bloodstream to use for energy. The problem with your danish breakfast however is that the amount of sugars and carbs that your body has to deal with causes a massive spike in your insulin levels which makes your body store as much as it can. Since your glycogen stores are full, your body stores the rest of the energy as fat. Once that happens you now have a massive amount of insulin in your system which causes your blood sugar level to drop too low. Your intake of excess sugar has swung the pendulum too far and now as it swings back your blood sugar drops and you crash. Simply stated, you pushed your body too hard with the amount of sugar and carbohydrate you ate. With the low blood sugar comes cravings for something to get your sugar up. Your body knows what it needs because your diet has conditioned it to know. Sugars or carbs. And so the cycle begins again. But enough of the stuff you already know, what about this NIMGU stuff?
So what happens after a regular workout? You have done your Plyometrics or Crossfit workout for the day, you have burned a bunch of glycogen from your muscles and liver stores and need to get those stores back to capacity. Well, that is where the interesting part comes in. As stated above, usually your body senses what you are eating and converts it to sugars, filling your stores and spiking your insulin levels in direct proportion to the amount of sugars (read carbs) you take in. But right after you exercise, typically for 30 – 60 minutes, your body behaves a little differently. It is in a state where it knows that the critical stores for survival (muscle and liver glycogen) are low and it goes into express mode to refill them. It does this by means of Noninsulin Mediated Glucose Uptake. As it’s name suggests, this is a time when your body will accept glucose in the form of sugar and carbs but it is not dependent on the usual insulin response to store that energy as glycogen. Even so, your body is in a hyper sensitive state to insulin and the mechanisms for storage of calories into glycogen is improved. So you get to eat your carbs without the spike and crash usually experienced due to the insulin response. There has been a lot written about this, much of it more eloquent and helpful than this but I think it is important that people at least have an idea as to why they should eat after working out. It is important to note that the type of food to be eaten is important, and you should not be trying to spike your insulin levels by eating excessively carb or sugar loaded foods. What you should be doing is taking advantage of your body’s post workout hyperinsulinemia to get some starchy carbs into your diet. It has been proven, in fact, that low GI foods are best during post workout times versus high GI and in fact the next day performance is improved when taking on low GI post workout calories.
Long story short, what should you eat after a workout? Well, its pretty simple. Starchy carbs are the goal, but not fruit. The problem with fructose is that is tends to increase the glycogen stores in the liver and once the liver is full your body trends towards normal insulin response rather than backfilling, so to speak, the muscles. So sweet potato, chestnuts, even regular white potato are great options to give you the replenishment you need and the satisfaction of moderate carb intake should you still have the odd craving.
That post is so ridiculously long and complicated that it bears a brief explanation:
I thought you ate carbs after working out because you snuck by the insulin response. Turns out that may not be accurate, but eating yams after a workout is still the right end result.
Anyone with a clearer view of this NIMGU / NIMGT thing please chime in…
Workout of the day:
3 rungs @ 70 lbs (Almost killed me!)