Carb-loading pro or con

I talk with a lot of different types of athletes and amateur runners on a pretty regular basis and the subject of carbohydrate loading is a common point for discussion - when to carb-load, when not to carb-load, is it effective, what foods are best to eat, etc. The subject of carb-loading always draws questions and does not lack in controversy with some folks.

Let's start with a definition of carbohydrate loading. Carb-loading is a planned change in the amount and type of foods you eat to help maximize muscle glycogen to increase enzyme glycogen synthesis prior to endurance exercise or competition. This involves eating an increased number of calories from high-carbohydrate foods like breads, pasta, grains, rice, potatoes and others, usually done a few days prior to endurance training programs or races. When your muscles have an extra supply of fuel from carbohydrates, research has shown improvements in performance over longer distance by 2 to 3 percent in some athletes.

Back in 1960, Olympic coaches and other professional trainers/nutritionists had originally developed a strategy to deplete your muscle glycogen through a low-carbohydrate diet for a few days prior to carb-loading. The thinking behind this was to trigger a stronger enzyme glycogen synthesis process during the loading phase. It was thought that when you combined the depletion phase with the loading phases you could increase your muscle glycogen stores beyond their usual resting levels. Later studies found that the depletion phase was not necessary since the additional glycogen synthesis was minimal at best.

So who should carb-load? Here's where it gets tricky, for two reasons. First, carb-loading is really only effective for intensive exercising or endurance races like a marathon that last more than 90 minutes. For short runs or workouts, carb-loading is only going to add calories to your diet and will not drive better performance. The second factor is based around your conditioning, aerobic capacity, musculature and body composition. This aspect is where differing views on the subject kick in. Some research has shown that athletes that have solid aerobic capacity or V02 Max and larger musculature benefit the most from carb-loading. Thin or lean runners, for example, with less leg musculature have less capacity to store glycogen in their muscles, which limits the positive effects of carb-loading.

Now a runner with less upper body mass but great lower body muscular is optimal since less mass requires less energy consumption and more muscle density means more glycogen stores.

It is true that carb-loading is a long-standing method for many elite athletes, especially runners and endurance folks as the best way to fuel for races. But I would like to make a point here that I personally don't believe carb-loading is a good thing for the vast majority of part-time athletes and amateur fitness folks. Most of us just do not need the extra calorie load based on the duration and intensity of how we exercise.

There are a number of issues that come with the practice of carb-loading. If our carb-loading does not get used, our bodies love to convert them in fat stores. Too much carbohydrate consumption can trigger insulin resistance and lead to obesity. Another downside to carb-loading is it comes with water retention since your body stores water with all those carbohydrates. Staying hydrated during exercise or competing is important, but too much carb intake can cause unnecessary water weight gain and in fact, work against you during intense physical activity like a triathlon or distance race.

These glycogen stores found in your muscles and liver are used first by your body for quick energy during elevated exercise or physical activity. Since carbs get used up so quickly, you really need to rely on more than glycogen from carbohydrates for a fuel source. This leads us to your other fuel, which is fat.

The best way to approach a balanced exercise and fitness fuel program is to be a fat burner with carbohydrates as your go-to quick fuel. Teaching your body to become a more efficient fat burner is far more effective for a long lasting fuel source. Many Ironman pro-athletes design their nutrition around both fat for fuel and carbohydrate intake on the course. So it is important to know that your body can be tuned to use fat as an effective fuel source, one that most of us have plenty of in our bodies.

We evolved to use fat for energy during normal daily activity and glycogen was not our preferred fuel unless we needed a quick burst to feed our muscle cells under short burst of intense activity. In fact, our musculoskeletal system including our cardiac muscle and brain prefers fat for fuel and this increases during low carb intake, which triggers ketosis. Ketones are compounds produced in our bodies to burn fat stores.

Carbohydrate loading can be an effective way to add a small edge to your endurance workouts or competition if key factors are in place. The better approach is to teach your body to become more fat-adapted less dependent on the quick energy of sugar/glycogen adapted energy that comes along with our daily high intake of carbohydrates. Consider replacing empty carbs and grains with healthy fats. The other aspect that can help tune up your body to burn fat more readily is restricting food consumption a few days a week or even do short fasting.

The bottom line to carb-loading is that it must fit the exercise, meaning 90 minutes or longer before it helps your performance - and your body composition must be factored in. Carbohydrates alone are not enough to fuel intense workouts or competitions, so building a solid nutrition program around good fats, protein and complex carbohydrates is key.

Judd Jones is a director for the Hagadone Corporation.