Exercising for longer periods can stimulate your appetite. Endurance athlete and coach Brock Armstrong joins me with tips on how to avoid unwanted weight gain when training for endurance sports.
A Nutrition Diva listener recently wrote in with a familiar dilemma: She and her husband were training for an endurance event, but as she increased the duration of her workouts, she noticed that her appetite was also increasing sharply.
“Even though I was eating more, I was still hungry all the time,” she wrote. And so she experimented with the timing and the composition of her meals, but nothing seemed to help. And she started to get worried that despite all the extra exercise she was doing, she might end up gaining weight just because she was eating so much more.
Joining me to talk about how exercise—and endurance exercise, in particular—affects our appetite is Brock Armstrong, host of the Get-Fit Guy podcast. Brock is also my cohost on a brand new podcast called Change Academy.
But more to the point, Brock is himself an endurance athlete. He's coached hundreds of others through endurance sports and training.
Click the audio player above or listen on your favorite podcast app. You can also read the transcript here.
What do we mean when we say endurance exercise? Is there a definition for that?
When people talk about endurance sports, it's generally something long like a marathon or a half marathon or an iron man or an ultra-marathon or something like that. So, for this conversation, let's focus on those longer, slower efforts, not necessarily the shorter quicker ones.
Are long duration, low-to-moderate intensity workouts the best way to get fit?
I always define fit as being able to move through the world and do the things you want to be able to do with a certain amount of ease and a certain amount of confidence. So endurance is definitely part of that, but it's not the whole picture. So it's not necessarily the best way to get fit, but it is a component of what I would consider to be fitness along with things like flexibility, strength, having the speed as well for shorter, higher intensity efforts. That all works in concert to equal fitness.
I define fitness as being able to move through the world and do the things that you want to be able to do with a certain amount of ease and a certain amount of confidence.
How does that type of training affect hunger levels? Does it have different effects in different timeframes—while you're exercising, immediately afterward, or maybe much later in the day?
Generally, what happens when we start to exercise is our blood circulatory system moves our blood and focuses its energy on the muscles or the parts of our body that are being used currently. So that means your digestive system actually isn't that involved when you're going for a long run, let's say, or a long bike ride.
So you don't necessarily feel hungry and you actually have an impaired ability to digest things when you're in the middle of a long effort like that. Now after that's finished and that blood serve returns to its more regular scheduled program, then you could feel an uptick in your hunger, or a return to your hunger because your blood is then returning to your digestive system.
And that's generally when people start to feel hungry. And that can happen within minutes of finishing an exercise or hours later. And that is very individual. I know athletes who are ravenous the minute they cross the finish line. I know other athletes that are actually kind of nauseous for a couple of hours after a race and you can't even show them food. It's a very individual thing.
Is that uptick of hunger just a physiological response to the uptick in energy use? So your body registers the fact that you've burned a bunch of calories on this exercise. Or is it more complicated than that?
It's much more complicated than that. There are so many different factors that come into play and, and some of it I think is habitualized as well. And this is something that I wanted to focus on during this conversation. We tend to spend so much time thinking about the calories that we are burning when go out for that run. I think we do prioritize replacing those calories perhaps more than we need to. And that gets us in the habit of feeling that extra hunger when we finish
I think it's possible that if we have exercised, we subconsciously think we have earned more food or we deserve more food. And maybe that translates into feelings of being hungry or having the urge to eat.
We have been sold the idea by the sport nutrition industry that we need to refuel. And that you have this window of time that you need to get the protein and the carbohydrates into your body. And a lot of that information is trickled down from professional athletes who are in a whole different realm than we are.
We have been sold the idea by the sport nutrition industry that we need to refuel.
And I think we do take that information and, even if we're not thinking in the forefront of our brains, it is jumping around in the back of our brain and perhaps sparking some hunger that isn't necessarily there.
Is it possible that the increase of hunger is exaggerated? In other words, we are stimulated to eat even more than we need in order to replace what we've just burned?
I think that's definitely a phenomenon that happens when people first start to do these longer endurance sports. For people who are first increasing their distance, that kind of reaction does happen to a greater extent than it does to somebody who's been doing it for a longer time. When my clients are expressing this concern of, “I'm just so hungry and I'm eating way too much, and I'm afraid that it's going to sabotage my efforts to either maintain a healthy weight or to achieve a healthy weight,” I generally say, “Don't panic. Just let your body sort of adjust to this new normal. We're taking you out of that homeostasis right now in increasing the volume and duration and sometimes the intensity of the workouts.”
And that's where those hormones really come into play. There are two hormones in particular that I know you've talked about on Nutrition Diva podcast episodes: ghrelin and leptin. These are the two hormones that either signal hunger or shut down hunger. And they're thrown for a bit of a loop, especially when you first start these longer efforts or even the more intense ones.
So it sounds like that's a real phenomenon, but it may be very temporary that your body then adjusts.
That's been my experience. It's much more pronounced when you first start these kinds of efforts and dies off with time.
Is there a difference between different styles of exercise? Are some kinds of exercise more likely to stimulate appetite (or to a greater degree) or others less likely to do that? I think I've seen somewhere that maybe high-intensity interval training is less likely to stimulate the appetite. Is that true?
Well, like all things, when you look into enough studies, you can find studies to support both sides of the coin. And actually, in preparation for today's conversation, I ran into that same problem where you find a study that says that long endurance sports actually suppress appetite and then ones that say it sparks it more than the shorter, higher intensity stuff.
So, then there are the studies that I find a lot more meaningful, where they're talking about the fact that it really depends on things like your gender, your level of obesity or body composition, your current fitness, the temperature that you're exercising in, the altitude that you're exercising at, the amount of hydration that you've had before, during, and after the workout … Hydration can play a huge role in hunger signals, especially after exercise.
It's really tempting to say, 'Please tell me what kind of workout I can do that's either going to suppress my hunger or make me hungrier.' But the truth is that it's a lot more nuanced than that.
So there are just so many factors to take into consideration. I know it's really tempting to say, “Please tell me what kind of workout I can do that's either going to suppress my hunger or make me hungrier.” But the truth is that it's a lot more nuanced than that. if you've been listening to Monica’s or my podcast for a while now, you probably are not surprised that we don't have a magic pill for you here.
So, apart from just this issue of how hungry we feel and satisfying that hunger, can you talk a little bit about how we need to eat in order to optimize our performance?
It's not really that complicated. Again, the sports nutrition industry has given us this trickle-down information from the professional athletes who need to be very on top of all their fueling and refueling. For the most part, for mere mortals like us, even if you're training for a marathon, we just need to eat our next scheduled meal and maybe add a little bit of extra food.
For these long slow runs, these endurance efforts that we're talking about here, popping those gels and gummies can contribute to this problem ... They can really spark the appetite and send you on that roller coaster ride of high blood sugar, low blood sugar, which doesn't necessarily stop when you've finished that run; it'll continue throughout the day.
So what I would suggest is for those kinds of long efforts is to just eat as you normally would. And if you know you're going to get hungry during the run, taking some real food with you can actually be just fine and a lot more satisfying. Things like a handful of nuts or a banana, or I know people who've cooked small baby potatoes and carried them along with them. There are real food choices that you can take on these kinds of runs. And by eating that normal type food, we don't set ourselves up for that extra hunger later on in the day that you do from the ultra-refined stuff that a lot of people take on their runs.
I think a lot of us think that if we're starting to feel hungry, we are on the verge of athletic failure. Does feeling a little bit hungry impair performance? Is it possible just to decide, “I'll just run through that and I'll eat when I get to the end of my session,“ or is that dangerous?
That's not dangerous at all. And in fact, I know a lot of high-level athletes that feel wrong if they aren't a little bit hungry at the start line. We store glycogen or glucose or carbohydrate in our muscles and our liver. At any given time, we've got at least 90 minutes of glycogen. When you're feeling hungry. It doesn't mean that you've run out of blood sugar. And it certainly doesn't mean that you've run out of glycogen. And it certainly doesn't mean that you've run out of fat stores, which do serve as a fuel source for any sort of movement.
I think that this is a confusion that people who are not endurance athletes also have—that the feeling of hunger signals dangerously low blood sugar or any number of other catastrophic events. And it's, it's in general, not quite as big an emergency as many of us have come to think of it.
No. But having said that, if you want to perform at your absolute best, getting some food in is a good idea. I'm just saying that it's not an emergency and it's not going to actually ruin your workout if you're a little bit hungry.
So what are a couple of tips that we can offer for people who like to do this kind of sport to help them avoid unwanted weight gain?
I think the first one would be to not worry about, that it will pass with time. Just do your best to manage it until your body adjusts to the new normal.
The second thing would be to avoid those highly processed sugary things that we've been told we need to have every 20 minutes. I'm not saying that they don't have a place, but in general, we don't need those kinds of things on a regular basis.
Putting too much stock into how many calories your activity tracker is saying you burned will probably cause you to eat more than you need to.
The third thing would be to not get hung up on whatever your activity tracker is telling you in terms of the calories that you've burned. The calorie estimations in particular from these devices can be up to 90 percent inaccurate. So putting too much stock into how many calories your activity tracker is saying you burned will probably cause you to eat more than you need to. Instead, focus on your actual hunger. A little grumble in your stomach is not an emergency.
And, as a final sort of caveat, please don't use exercise to burn calories and promote weight loss. It is a very ineffective tool. It's a great way to support your weight loss efforts, but as the great Dr. Tim Noakes says, “If you have to exercise to maintain your body weight, your diet is wrong.”