In part 2 of this Exclusive Interview, Sheri Colberg talks with Diabetes in Control Publisher Steve Freed about the true effectiveness of carb loading before athletic activity.
Sheri Colberg, PhD, FACSM is Professor Emerita of Exercise Science at Old Dominion University in Virginia and a member of the Diabetes in Control Advisory Board.
Transcript of this video segment:
Steve Freed: So what about carb loading? You still see that when they have the marathons, the night before they invite all of the runners and they load up with carbs. Does that philosophy still work?
Sheri Colberg: You know that has changed a lot since I’ve been in the exercise physiology world. When I started out the carb loading regimen, the glycogen loading regimen, was a week long. You would first do this depleting bout of exercise and then you’d go on a low carb diet for three days during which time you would feel absolutely horrible because your glycogen levels were so low. Then you would spend three days on a high carb diet and then you’d go into the event glycogen super compensated. But over time they found that it didn’t take that long to do that. In fact you can pretty much effectively glycogen load in just a single day of taking in adequate carbs and tapering or resting that particular day so you’re not using up the glycogen, and you can do a high intensity taper where you may actually stimulate a little extra glyc to be replaced, but typically it takes 24 to 48 hours to fully replace that you don’t want to deplete more than you could put back in by the time your event starts. So one day is probably effective.
There is actually only one study in people with type 1 diabetes that looked at carb loading and in that particular study they had two different percentages of carb intake and that basically diet one was around 50 percent of calories coming from carbs; the other was close to 60, it was like 59 percent, and they actually found in the group that was at 59 percent, or the higher amount, that their glucose levels were running higher their insulin requirements were higher and they stored less glycogen. So I think the real key to keep in mind is that in order to effectively restore glycogen and carb load you have to have optimal glucose management and you have to keep that level as normal or as near normal as possible, which means taking enough insulin to cover the carbs that you are eating, and if you do that probably it takes a minimal amount of carbohydrate. No study has looked at this really effectively but in in training athletes, they can get by with as little as 40 percent of their calories coming from carbs. And as long as they’re taking in adequate calories they’re able to glycogen replenish on a daily basis without any problem. So in these athletes with diabetes who claim to be taking in fewer than five to 10 percent of their calories as carbs it could be a little bit more difficult if they’re actually that low, and it may take a couple of days of taking in maybe slightly higher amounts of carbs, but I think that on the whole the “we’ve got to have a pasta party in order to carb load” thing is totally overblown.