Many people ask what I like to do in my spare time. While my days are typically jam packed helping baby seals find their mothers, teaching orphans how to read, and reciting poetry in Boston Common with my shirt off; I also like to set aside a few minutes each day to discuss some common myths in the fitness/nutrition world.
One such myth that still tends to be quite common is the notion that ingesting carbohydrates around training will inhibit fat loss. For those who are trying to lose some body fat this has implications. What should you do? Lets keep this short and sweet.
1. Both resistance and endurance exercise up-regulate muscular insulin sensitivity. Without getting too much into the boring science (GLUT-4 receptors permeate to the cell membrane so that they can bind to glucose), this is often the reasoning behind the saying “take advantage of that post-training window.”
In a nutshell, following training, skeletal muscle is primed to take up nutrients at an accelerated rate. You could think of your muscles as a sponge just waiting to absorb all those nutrients you take in after training. What’s important to note is that during this post-training window, most (if not all) nutrients taken in will be shuttled to muscle and not fat cells. As a matter of fact, following glycogen depleting endurance exercise, research has clearly shown that ingested carbohydrates go towards glycogen storage while the body still continues to rely on fatty acids for fuel.
Granted the above refers to endurance exercise, but the same can be applied to those who only participate in resistance training as well; just to a smaller degree.
2. One cool study showcased the above points exactly. In terms of De Novo Lipogensis (DNL), or the making of new fat cells, it was shown that DNL did not occur in subjects who ingested 500 grams of CHO after 90 minutes of moderate exercise. As a matter of fact, the body continued to burn fat in the post exercise period.
Folch, N. Metabolic response to a large starch meal after rest and exercise: comparison between men and women. Eur J Clin Nutr. (2003) 57(9): 1107-15.
The basic gist of all of this? When glycogen levels are depleted (as they are in INTENSE exercise…a key point to remember), incoming carbohydrates go towards glycogen storage while the body continues to utilize free fatty acids for fuel. Ingesting some carbohydrates post-training (thus raising insulin levels) does not interfere with this.