The Case for Carbohydrates Part 4.
The last part of the series, we are going to talk more about why you often hear the advice to consume your dense carbohydrates post workout (pwo). We will cover the why behind the what, and who should be participating in the pwo carb indulgence.
Firstly, I want to make it clear why I made these posts. Carbohydrates in general have got a bad rep from the low-carb community. When Gary Taubes came out with his magnum opus “Good Calories, Bad Calories,” he smacked the nutrition world, myself included, directly in the face. He destroyed the lipid hypothesis, showed us why observational studies are barely worth the paper they are written on, and didn’t just show correlations, but actually plausible mechanism for how sugar is the driver of western diseases of civilization (CVD, Diabetes, Cancer, Alzheimer’s), while finally lifting charges on crimes that fat never committed- only an innocent bistandard. Back to the reason for the series; its not the macronutrients that are the issue, it is certain types of macronutrients, namely; fructose, linoleic acid & grains. The Kitavan’s eat a large portion of their calories from carbohydrates (up to 67%) and are free of any metabolic disease. Why? Well their main sources are tubers, and they consume very little fructose and no grains. Shocker.
Okay, enough background- let’s get into this post!
Who does this pertain too? Any hard charging athlete. Too vague? Okay, anyone that can see their abs and who is hitting workouts that a very glycogen demanding (think short and hard).
Exercise increases the rate of glucose absorption in muscle tissue by a process called “non-mediated glucose transport.” The “non-mediated” portion refers to the ability of cells to take in glucose without the aid of insulin. If you’ve been on the blog before, you should have a basic understanding that insulin is the storage hormone- often referred to as the “master hormone.” But, during exercise we have an increased need for metabolic substrates, and all the hormones that are going hay-wire like cortisol and adrenaline are all working to mobilize energy in order to keep our machinery working as efficiently as possible. During exercise, the receptors that absorb glucose into the cell, as brought to the surface without the aid of insulin. These receptors are called GLUT receptors. Specifically, it is the GLUT-4 receptor that comes to the surface and invites glucose into its dwelling. This is a great little trick, as we can consume large amounts of carbohydrates in the pwo window, which turns out to be within an hour after exercise. After roughly 45min-hour the process is basically non-existant.
To make it as simple as possible- we can get away with consuming a good dose of carbohydrates without negatively effecting insulin sensitivity. We want to use starchy sources of carbohydrates like; sweet potatoes, yams, bananas, as starch breaks down into glucose rather quickly. Glucose will go directly to muscle glycogen where as fructose needs to travel through the liver first, so it will preferentially fill liver glycogen. Fructose containing carbohydrates are a good choice when we are competing in a multi-event day format/ training multiple times a day.
Context matters here. If someone is doing the CrossFit workout “Grace” (30 clean and jerks at 135lbs for time) and they finish it in 2 minutes, they can definitely justify a sweet potato or two. But if they do one clean and jerk every minute, they can do with just some protein and fat. Remember- the rule is, if you’ve got abs and are hitting these types of workouts, carb up. If you’re not lean yet, stick with a protein/fat meal that has adequate calories. Everyone should be eating themselves until satiated.