In part 1 of this Exclusive Interview, Sheri Colberg discusses the dietary habits of athletes in a talk with Diabetes in Control Publisher Steve Freed.
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: We’re here at the 78th Scientific Sessions from the American Diabetes Association, and we have with us a very special person, Sheri Colberg, who’s a PhD. exercise physiologist and has written I think at least twelve books, and we’re here to find out some more information about exercise. So first tell us a little bit about yourself.
Sheri Colberg: Hi I’m Professor Emeritus of Exercise Science from Old Dominion University. I’m currently just working on writing and educational materials for people with diabetes, to help them be physically active and have a healthy lifestyle.
Steve Freed: Well you know when it comes to exercise we can’t really talk about exercise without talking about diet. You can’t eat eight Big Macs and run 25 miles; people just don’t do those things. So let’s start off with the question about low carb diets, especially when you’re exercising. What are your thoughts on low carb diets? Because we know that if you eat low carb, your blood sugars are going to go down, but then you have to have carbs when you do physical activity. So how do you regulate those things?
Sheri Colberg: Well it’s really interesting. I’m working on a revision of my book, Diabetic Athlete’s Handbook, and in in revising that this go round a decade later I surveyed a number of athletic people with type 1 diabetes, mostly through an online survey and found out what do they do in terms of their diet and activity levels and so forth. I had nearly 300 people answer my survey, and it was very interesting because quite a few of them actually follow some kind of low carb eating, which is a lot higher percentage than the last time I surveyed athletes about a decade ago. And so I was very interested to see how they handle low carb eating and being physically active.
What appears to be the case, and this is sort of a trendy thing now, for even nondiabetic athletes or other people, is to try to go on a ketogenic diet, or you know go for the ketones, and the whole idea is having some greater fat adaptations so that when you’re physically active you can use a higher proportion of fat as the primary fuel because it’s virtually unlimited compared to our carbohydrate stores which are fairly finite. And. I was surprised to see that many of the athletes with type 1 are able to eat low carb and still do normal athletic training and participate in ultra endurance athletic events and other things. So I looked up the research on that as well and it appears that in general — I mean this is looked at and looked at in regular athletes before — that low carb eating could potentially be detrimental to your performance when you’re doing events where glycogen is the really key thing; like if you’re doing near maximum or maximal thing, doing Olympic weightlifting or you’re actually even playing soccer or something that uses up a lot of glycogen, low carb eating and fat adaptation could actually have a negative impact on performance.
But doing most of the things that these athletes did, which were regular things like running, swimming, cardio types of training, they actually fat adapt pretty well and are able to, at least in studies in non-diabetic athletes, restore glycogen fairly effectively even on a low carb diet.
So the real question is, how low carb do you need to go in order to have optimal blood glucose management, which is why a lot of these people were doing it, and that is actually an ongoing study in Scandinavia right now. We’ll look at the effects of low carb eating and A1c and blood glucose management, and I don’t think that you actually need to go as low carb is being extremely low carb. I found with these athletes that some of them that were on a low carb diet didn’t necessarily have a better A1c than athletes who eat more moderate amounts of carbs. But I would say that the one thing that is very characteristic of all of them is that they are carb conscious and they pick their carbs carefully so that they avoid huge spikes in their glucose.
They don’t just eat pizza and huge amounts of pasta whenever, they actually moderate their carb intake. I would say all of them are not on a low carb diet but most of them are on a low to moderate carb diet, and have learned to adapt to training doing that.
So it might be useful to, with that adaptation — and actually as we know it takes several weeks to really rev up that fat metabolism and be able to metabolize the fat really effectively — so if you’re going to try something like this you wouldn’t want to just go on a low carb diet and then go try to exercise right away. I mean you need several weeks to adapt to this. But they have found that athletes are able to increase the amount of fat that they’re able to use during any given activity so they’re at a higher percentage of their maximum than before and it’s probably not bad to be somewhat fat adapted for most of the types of training that people do on a regular basis. It’s only in certain sports where it could be detrimental.