Carbs and Running

Carbs and Running


Spring is around the corner and I know that many of you are itching to get in some outdoor running.  Some of you might even decide to sign up for a road race… 5K, 10K, maybe a ½ marathon.  Here’s my take on carb intake while running or race training.


When I used to run marathons, I was always so surprised, standing in the starting corral, by the state of the human bodies around me.  I was surrounded by thousands of people who had trained to run 26 miles.  Most of them had dedicated at least the past 12 weeks to getting fit enough to manage to run this distance. Why was I looking at muffin tops and pot bellies? Shouldn’t I be standing next to lean bodies with minimal body fat?  Most of these people were probably fit enough to run the marathon and run it well, at that. So why didn’t their physique match their fitness level?


The problem wasn’t a lack of fitness. The problem was in the nutritional approach most were taking during training, especially pre-race day.  Most carbohydrate loading robs us of the opportunity to actually burn fat.


You can look at it from a very basic physiological point of view.  When we load carbs in our body by eating pastas and breads, which are also forms of glucose, and then that glucose is stored as glycogen in the muscle, we must first burn all of the glycogen before we burn fat.  


Problems with Carb Loading


Problem 1: We don’t ever allow ourselves to burn fat because we are always burning glycogen, or carbs. Thus, we don’t lose any weight.  


Problem 2: The carbs we don’t burn get converted into fat in the body. This means that, when we are not running or training, the excess carbs that aren’t stored as glycogen are stored as fat.  


Problem 3: Burning carbs as fuel is not sustainable.  We have to continue to replenish carbs as we have trained our bodies to depend on them and the storage is limited.  Burning fat is a longer lasting, much more sustainable fuel, that we have at least two times more storage capacity for compared to carbs. Not to mention, it supports increased metabolism and a lean body.


The Solutions to Carb Loading


Solution 1: Cut carb intake. Start getting used to cutting carb intake on a regular basis so that you can begin to burn fat as fuel. On lighter training days, limit carbs between 100 grams to 50 grams. On longer training days, try not to exceed 150 grams.


Solution 2: Change the carbs you eat. If you need to use carbs as a fuel, then you should stay away from anything that has added sugar. That’s pretty much any sports drink or energy bar.  The added sugar ferments in your stomach and causes bloating, dehydration, and gas, while at the same time making you dependent on continuously re-loading with carbs once you begin to run low, again, not allowing you to burn fat. Instead, try eating things like sweet potatoes, yams, rice, white potatoes and fruit. These will provide satiety and won’t have nasty side effects.  


Solution 3: Train low and race high. This is a good way to begin to bridge the gap. Simply put, when you are training, try to limit carb intake to 50 grams or less per day, thus allowing the body to get used to burning fat. When you race, increase carb intake to no more than 150g, using the foods I listed in Solution 2. Keep in mind that the old rule of carb loading doesn’t apply because you can only store about 2000 calories of carbs as energy in your muscle.


I cannot stress this point enough. We do not need to increase intake of carbs during training unless we are working for over 1.5 hours. Most of us store about 2000 calories of glycogen in the body at any point in time. That is plenty of glycogen to burn for at least 1.5 hours of aggressive running.