In my last post, Get rid of your sugar cravings, I explained how ingested carbs are dealt with in the body. I purposely avoided the discussion about which types of carbs and in which amount should we eat. It turns out that not all carbs are created equal, and it is important to know which carbs to choose to insure a healthy metabolism, and avoid fat gain, unstable energy levels, and ultimately, insulin resistance, that leads to cardiovascular disease, high cholesterol, obesity, and hypertension. Watch Greg Glassman explain this in a quite convincing manner!
But now back to carbs! Carbohydrates are macronutrients, like are lipids, i.e. fats, and proteins. But carbs are made up of molecules arranged in different configurations, that determines their function. So within carbs, you can recognize fibre, starch and sugar.
Let’s talk about fibre first, one of my favorite topic! It turns out that fibre is not digestible by the human digestive system… but the one trillion bacteria in our gut can! Fibre is the primary energy source for intestinal cells, which explains the conventional wisdom of eating fibre to have regular bowel movements. But wait again, not all fibres are the same neither! There are two types of fibre, soluble and insoluble. Now, let us clear this issue. Insoluble fibre solely increases the mass of the stools, increasing the transit time through the intestines. However, soluble fibre enhances the thickness of the stomach content, which slows down stomach emptying. This is a good thing, meaning that eaten with protein and fat, soluble fibre ensures that the food you ingest will be properly processed and the nutrients absorbed, and you will feel satiated for a longer period of time! Hence, a diet rich in vegetables and fruits will ensure the proper intake of good fibre that will regulate the digestive system.
Then, there is the sugar category… There are two types of natural sugar: fructose and glucose. Fructose is a simple sugar found in fruits and vegetables that is toxic at high doses. In fact, fructose damages proteins, which causes inflammation and oxidative damage. To prevent this, fructose is directed to the liver for conversion into glucose or fat. But beware, this process can be disrupted over time if it is abused of, leading to non-alcoholic fatty liver disease… Hence, limit your intake of fructose to a few servings of fruit per day, an avoid at all cost high-fructose corn syrup, agave nectar, and other high-fructose content foods.
Glucose is another simple sugar found in fruits, vegetables, and grains. It is a source of energy for the cells; it is essential for our metabolism, so much that, the human body evolved to be able to produce it even in its absence from the diet!? In a healthy metabolism, glucose is digested and rapidly taken up by the liver and the muscles cells (remember the last post about glycogen). Hence, assuming no metabolic problems and an active lifestyle, glucose may be consumed daily in a quantity of 50-150 g.
Starch is a carbohydrate consisting of a large number of glucose molecules bonded together and is stored in plants, like sweet potatoes and winter squashes. Because of the structure of starch, its digestion is slower than that of simple sugar, and hence do not cause a sudden rise of insulin in the blood. It is therefore a valuable source of energy, particularly after an intense workout to replenish your depleted glycogen stores.
Now keep in mind that as a Crossfit athlete doing High Intensity Interval Training, your energy requirements are higher than the average sedentary population. You need to have glycogen stored in your muscles in order to perform your workouts, and you need to ingest a certain amount of carbs, mostly in the form of glucose, to keep this metabolism active. That means making sure you are eating enough Whole Life Challenge “legal” carbs to fuel your workouts, in the form of fruits and vegetables.
Today is the Murph Challenge at the Westshore gym. The doors open at 7:30am. We anticipate more than 50 participants, so there will be more than one heat. If you would like to carpool from downtown, please post in the comments section. See you tomorrow!
