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.
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.
Steve Freed: Let’s be a little more specific when it comes to exercise. Diabetes and exercise, that’s what you’re known for. Is there a particular exercise for type ones, type twos? The average type 2 is overweight, has high cholesterol, hypertensive. Is there something we can say it’s the best exercise, cause we know that it’s something that they should do on a regular basis, whatever that may be. Is there one that sticks out – swimming, bicycling, walking, jogging, lifting weights? It gets a little bit confusing. But if there was one that I knew, this works the best, if I’m going to do it, what would that be?
Sheri Colberg: Well when people ask me that question, because I basically taught people to do cardio training, resistance training, balance training, flexibility training, and be more active all day — when I get, “What? I don’t have time for all that. Tell me one thing to do.” — I always pick resistance training and the reason for that is simple. The place that we store most of the carbohydrate in our body is the skeletal muscle. And in order for our glucose metabolism to be effective we have to be able to store carbohydrates after we eat them. So if you have a smaller “glucose tank” which is this muscle glycogen storage tank, and it’s always full, you have nowhere to put carbs when you eat them. And it can elevate glucose or it gets turned to body fat. You know none of these are good consequences. So what we want to do is keep as much muscle as possible which we can only really do very effectively with heavier weight training. And we want to keep that muscle glycogen tank partway empty all the time, which we can do with any type of training. So if you are regularly walking around and doing some moderate activity during the day you’re using up some of the glycogen; if you’re doing resistance training at least two to three days per week, not consecutively, you’re able to maintain your muscle mass better and that gives you a bigger glucose storage tank.
And so I think that’s really the key; with aging we’re losing muscle mass or particularly losing those faster fibers that we’re not recruiting when we’re just walking and doing normal activity. So we need to recruit all the fibers; we can do that with some little bit heavier resistance training or you could do it with sprinting, but sprinting is not going to be for everybody.
Steve Freed: So for the average person who’s 60 years old, comes to the doctor’s office, if the doctor, rather than just saying increase your physical activity, says I want you to do some resistance training; can you do pushups, could you get some weights or what would you recommend that most people can do that a physician can ask their patient to do? Most likely they’ll do it because it’s not like doing 100 pushups, right?
Sheri Colberg: Well actually the easiest thing to do, and it’s very trendy right now is doing body weight resistance training. So using your own body weight as resistance, and you can do a variety of things. Regular pushups are kind of a hard place to start for most people. So you can do wall pushups, so you basically you’re pushing up off the wall; you think that doesn’t feel too bad, you can do five. Try doing 100 and they feel like oh my gosh, I’m working something doing that! You can do lunges, you can do squats or partial squats, you can do planking which is not a lot of fun. You can actually do abdominal curls where you’re sitting in a chair, so a lot of these are adaptable for people or may have some mobility issues, are a little unsteady on their feet or have neuropathy. A lot of these bodyweight activities you can actually do seated or easily at home without going anywhere.
Then you want to ramp it up a little bit. You can get some inexpensive resistance training bands – they used to use them for Pilates but you can buy them pretty much anywhere and they come in different colors so they’re different stretchiness to provide different amounts of resistance. You can use little hand weights or you can just use full water bottles, things you can find around the house, a five pound bag of flour, whatever you want to use. There are many different things that you can do without ever leaving the home. So gives you no reason to say you can’t do it because you can do it at home.
Steve Freed: I recommend, take two bottles of Bud Light.
Sheri Colberg: [Laughs] Those 12 ounce curls! You’ve got to do a lot of those and then it’s eleven ounces and 10 ounces, then you’ve gotta get a new one….
Steve Freed: I recently saw something on the Internet that I thought was very interesting about sports drinks. My first question is, for most people with type 2 diabetes that are overweight, who are going to go for — not even a walk, let’s say they ride the bike through 20 – 30 miles and they go through an hour walk or something, do they really need a sports drink or just water is sufficient, because less calories, they can burn more fat etc. Do people really need those sport drinks for most people, and those bars?
Sheri Colberg: No they don’t need them. So what we know pretty well from just normal athletes without diabetes exercising, is that if they’re doing an activity that’s less than an hour, usually water is fine. If they’re worried about hydrating they don’t really need sports drinks, you don’t need to replace your electrolytes in that short amount of time and you certainly don’t need to take in additional calories or glucose unless you’re using that to prevent hypoglycemia.
Steve Freed: Interesting. I recently saw a program that showed that if you can take a sport drink, swirl it in your mouth, spit it out, you get the same benefits as if you swallowed it. What are your thoughts on that?
Sheri Colberg: In terms of hydration and other things, there’s some ways it sort of tricks the body into thinking that you actually took in some fluids. It’s not the sports drink itself it’s just the fact that you had the fluid in your mouth. No, I wouldn’t suggest that for everybody. I mean a lot of people with diabetes actually are dehydrated if they have been having glucose that’s running a little higher so they’re losing a little more body water through urine and so forth. So you know, essential hydration, I mean it’s still good to hydrate on a regular basis but I mean in the short run if you’re feeling thirsty that’s a good way to kind of trick yourself, if you don’t have much water to go around!
Steve Freed: If you wanted to say to the family practitioners, the nurse educators, what are some simple things or principles, what’s the most important thing from your experience? You have to tell the patient; it’s easy to say exercise more; it doesn’t mean anything, because most people don’t do it.
Sheri Colberg: I think the most important thing honestly is to have people pick activities that they enjoy doing. One of things that we don’t talk as much about, we give prescriptions to say, do this, do this, do this. But if our patients aren’t doing it the whole issue is a behavioral one, not that they don’t know what they’re supposed to do or if they haven’t been told what to do. So in order to address the motivational issue we need to find out, possibly also talk to them somewhat about what their barriers are to being active. Why don’t they do it? And then in terms of adherence once they do start doing something, we know the things that cause people to drop out of exercise programs are: perceived lack of time, so you have to work around that, maybe by working it in as a lifestyle activity; they get injured, and that often occurs because people start out at an activity that’s too hard or too intense and so on and then they just don’t enjoy it. It’s not fun for them. So they want to make sure that they can pick the activities that they like to do.