Carbohydrate Manipulation

[Jean-Paul]

Carb-loading is a technique first developed by runners in preparation for a competition. This concept involves two phases: a depletion phase to reduce glycogen stores to minimal levels followed by a loading phase which will hopefully lead to greater endpoint glycogen stores due to overcompensation (storage) resulting, in part, from the extreme glycogen depletion which exists at the start of carb loading.

In the classic method to initiate carb loading, the muscles and liver are completely depleted in a long workout 4-7 days prior to the event. Several hundred grams of carbs are then consumed in the next 24 hours. Because the muscles are so depleted, most of the carbs are stored as glycogen, not fat.

The depletion could also consist of continuing light training and restricting carb intake. The loading phase could consist of continued very light training (or no training at all) and literally stuffing oneself with more the complex carbs. In all likelihood there will be some carb "spill over" into fat storage but we are really talking about a very short time period in the overall scheme of things, i.e. a week or so for the depletion & loading phase which would amount to a couple of days of some fat storage.

This can be quite stressful on the body (depending on how extreme the depletion stage is) in particular when occurring just before a strenuous event (Physical & mental) such as running a marathon. The procedure (time of depletion & loading) and benefits received will tend to be highly individualized. A world class marathoner might benefit whereas a middle of the pack runner might notice no difference at all. In extreme ultra-marathon distances (ranging from 50KM to 1000+ miles) carb loading just doesn't make any difference.

Most well-informed and well-trained endurance athletes no longer utilize the classic carb loading since most are now able to burn fat (body fat) as a high percentage of their fuel. They also know they can get enough carbs by eating a bit more carbs in the 1-2 days prior to an event, and right before and during the event. There is enough glycogen in you to get you through 60 minutes of training. Eat or drink carbs before and during, and you'll be fine up to about 3 hours. In other words, maintaining glycogen levels during the event itself can give as much if not more benefit.

Carb-cycling is slightly different. It involves varying your total intake of calories by 10-15% during the week in order to lose body fat. Determine the number of calories you need to maintain your present weight, and then depending on whether you're trying to gain or lose you add or subtract 10-15%. So if your target is 3000 cal, most days you would hit that, but one day you would hit 3300 and one other you would go down to 2700. You do this by changing total carbs. You can flip a coin or pick odd number days or choose some other plan to decide how to space apart the days—it doesn't really matter how you do it. Apparently this also works for gaining weight, but you just don't have a low day. It is not clear how well carb-cycling really works.