What’s the deal with exercise and your appetite?

Posted on August 12, 2015

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This is a topic I’ve always felt was rudimentary, yet the opinions on it seem to move around. Another title for this article could be “Is exercise good for weight-loss?”

I’ve trained a good amount of people who have said,

  • “I’ve been working out for six months now, but haven’t lost a pound.”
  • “I’ve been exercising for a while now, but I’ve actually gained some weight.”
  • “Exercise doesn’t work for me. I never lose any weight doing it.”
  • “I have a third nipple.”

Of course, there are people whose lives have been transformed by exercise. We already have the answer to this question…

Does Increased Exercise or Physical Activity Alter Ad- Libitum Daily Energy Intake or Macronutrient Composition in Healthy Adults? A Systematic Review

I was very interested in this paper not because I wanted to know the answer to this question. The answer is above. I was very interested in this paper because I had a hunch the paper would not do this topic justice.

From the abstract:

“Results: No effect of physical activity, exercise or exercise training on energy intake was shown in 59% of cross-sectional studies (n = 17), 69% of acute (n = 40), 50% of short-term (n = 10), 92% of non-randomized (n = 12) and 75% of randomized trials (n = 24). Ninety-four percent of acute, 57% of short-term, 100% of non-randomized and 74% of randomized trials found no effect of exercise on macronutrient intake. Forty-six percent of cross-sectional trials found lower fat intake with increased physical activity.”

“Conclusions: We found no consistent evidence that increased physical activity or exercise effects energy or macronutrient intake.”

Simple enough, right? Exercise doesn’t change how you eat, and since exercise burns calories, if you start exercising -burning more calories- but eat the same => you lose weight. Those who say they’ve been exercising for a while but haven’t lose weight are conniving little liars.

But I’ve trained these people. These tricksters. I’ve seen some of them three days a week for a year, yet they haven’t lost a pound. And no, they didn’t lose X amount of fat and replace it with X amount of muscle. (Barring teenagers, that’s pretty much always a Taylor Swift song (fairytale).)

While the conclusion above may be technically correct, it does not give the individual variance of this topic its due. This review examined what each study found in whole, but not what happened to each person in each study.

Let’s look at one of the papers this study used in its meta-analysis:

Acute compensatory eating following exercise is associated with implicit hedonic wanting for food

All I was looking for was a graph like this:

Exercise eating individuals

The dotted line is ~150 calories. That’s the average amount burned from the exercise done in this study. (This is right around what most will burn from their half hour cardio sesh.)

“Fig. 2 illustrates this variability in compensatory eating and demonstrates the range of responses including individuals who suppressed or made no adjustment to their intake and some for whom exercise stimulated energy intake. As the mean energy cost of exercise for the whole sample (n = 22) was 149.0 kcal ±11.2, REI [Relative Energy Intake] of equal to 150 kcal indicated complete acute compensation while REI of >150 kcal indicated overcompensation.”

22 subjects,

11 are below the dashed line.

1 subject is on the line.

10 subjects are above the line.

Almost perfectly, half the people overate after exercising, and half the people underate. Do this chronically, and we have the answer I gave above: Some people lose weight from just exercising, some gain weight, some nothing happens.

Furthermore, look at these daredevils!

Exercise eating individuals with outliers

This study had people either exercise or be sedentary (“sitting, reading”). A week later, the groups flipped. Relative energy intake measured the differences in how they ate after these two activities. After either activity, subjects ate an “ad-libitum” meal, where they were instructed to eat to “reasonable fullness.”

-> I didn’t like this instruction. Ad-libitum is eat whatever you want, however much you want. To then instruct people to “reasonable fullness” doesn’t make sense to me. It’s not how everyone eats, particularly some overweight people. I remember watching one person with weight issues eat. You could see her get to a point of, “I probably don’t need to be eating anymore…but go hard or go home.” Reasonable fullness didn’t exist. It was as if her body didn’t have a fullness sensor. There were some other things of this nature in the study, but it’s not especially relevant to this discussion. (Partially only me being pedantic.)

Exercise eating individuals with outliers

The pink circled person on the left eats so much less after exercising compared to not exercising, you wonder if they were on a laxative and afraid eat after being on the treadmill in order to have that much of a difference. You can also view this as this person eats so much more after being sedentary compared to after exercise. To work up that much of an appetite, the reading material must have been porn of a category I’ve never even heard of. (They could have also been really bored afterwards, which can cause eating.)

Meanwhile, the pink circled person on the right looks like they’re the type where after exercise they sprint to their car, drool while driving, weave in and out of traffic like Jeff Gordon, slurp their post-workout peanut-butter-banana-smoothie while intermittently snarling at others, “I NEED MY CHIPOTLE! I’VE EARNED IT!”

Taking these two crazy pinks together, we’re talking a ~1400 calorie swing here.

Takeaways

Some people gain weight from exercise, some lose weight, some it doesn’t do anything. This is what I feel is rudimentary about this. The answer of “it depends.” The people I’ve trained for a while who were telling me they haven’t lost weight, deep down, they knew why. They never changed their eating (despite my efforts). They’d often tell me so themselves. “Yeah, yeah, I know. I need to change my diet at some point. I was hoping exercise would take care of it instead.” [Turns around and I’m pretty sure I hear “jack ass” muttered.]

I‘ve said it before and I’ll say it again, be very careful only reading abstracts. Whether intentional or not, they hide things. I almost feel abstracts shouldn’t be allowed. Or tightly regulated as to what they say. It’s tough to not read into them, and they’re so much easier than reading a full paper. They’re the research world equivalent of Twitter. They give 20% of the story -if not less, but 80% of the reaction -if not more. Only read the review’s abstract I linked above and you may be telling your clients, “Don’t worry about exercise and your appetite. It has no effect.” Or “Just exercise and you’ll lose weight.” Sure, on average this may happen. But for 50% of your clients exercise may increase their appetite, where the other 50% it decreases. What if you’re dealing with the person who turns into a velociraptor after being on the treadmill for a while?

Exercise itself is never an impediment to losing weight. The appetite response after exercise may be.

-> Why would exercise increase appetite? This is a question there is no single answer to. I’m sure some researchers out there are looking into specific hormonal responses, always looking for that *one* factor, but appetite is insanely complicated.

Perhaps as a kid you grew up playing a lot of sports. You were pretty good. Played three different sports year round. Played in some tournaments in the summer. Because most practices were after school, by the time you got home it was dinner time. So you either went right home and ate dinner, or Mom didn’t feel like cooking, so if she loved you she stopped by Wendy’s before going home, or she stopped by Burger King and this is how you realized you were an accident.

You could also never eat before games, due to nervousness. By the time a game was over, you not only were feenin’ for Chipotle, you had the order down before anyone could ask.

“Hey there! What would you like..”

“Burrito (F a salad), black beans, white rice (that brown shit is so bland), yes yes non-GMO carnitas (what in the hell does GMO stand for?), medium sauce (I can put tomatillo on if it’s not hot enough), lettuce, cheese, sour cream (cause I just exercised!), guacamole”

“Guacamole is..”

“I DON’T CARE HOW MUCH YOU OVERCHARGE ME FOR GUACAMOLE!!! (I want that guac bursting through the tortilla like Jim Carrey coming out of a rhino’s ass)”

Jim Carrey Rhino

Plus, after a game, your parents often took you out for a celebratory meal. Or a consolation meal. After all, they were hungry too. Telling the refs how incompetent they are takes energy.

For 15 years you moved around a ton, then ate almost immediately afterwards. You probably ate a good amount too, since you were young, very active, and often stopping at calorically dense, albeit regurgiworthy (B.K.), places.

–> The last time I (reluctantly) went to Burger King, they ran out of burgers. I will use every synapse and myofibril I possess to not go back. Five Guys FTW.

Fast forward to your 20s. You move around some, we know because of your status updates #FitBodyFitMind, but you still eat a ton afterwards, we know because you don’t look like your old Instagram photos #APictureShowsAThousandCalories. 15 years has conditioned you. Now you’re the person saying, “I was so active as a kid, I did so many sports, but now I sit in a desk all day. I try to exercise, but I just can’t get the weight off sitting all day.”

You’re the person who now after nearly two decades, finally has to acknowledge you have to change your eating. You’ll probably never be able to be that active again, and the little activity you currently do, only initiates your appetite.

–> To reiterate, at least half of people who need to lose weight fit this category. That they need to adjust their eating. There is no shame in that.

I‘ve been saying for a long time exercise is unequivocally great for essentially anything having to do with human health. Except losing weight. When done in isolation, exercise as a weight-loss modality is no guarantee of success. But exercise is so beneficial for so many things, I’m not sure it’s even reasonable for the authors to state the following:

“Exercise-induced changes in the hedonic response to food could be an important consideration in the efficacy of using exercise as a means to lose weight. In particular, an enhanced implicit wanting for food after exercise may help to explain why some people overcompensate during acute eating episodes. Some individuals could be resistant to the beneficial effects of exercise due to a predisposition to compensate for exercise-induced energy expenditure as a result of implicit changes in food preferences.”

I don’t think anyone in the health world should be giving the general population any more reasons why they shouldn’t exercise. The general population takes care of that on their own. If you’re going to say something like the above, I think you’re ethically obliged to yell “BUT WAIT HOLD PAUSE. For some, so long as exercise is used in conjunction with dietary modifications, the benefits of exercise as a weight-loss modality are assured.”

What I think is reasonable is what I do with clients. I start with exercise and go from there. If the client asks me about eating, I tell them we’re going to start with getting into an exercise routine, and then in a few weeks or so we’ll start talking about the eating.

  1. This way we start with one life change at a time.
  2. Because for some, they get on an exercise program, and that’s practically it. The weight comes off, great things happen. Depending on how much weight needs to be lost, the second change may not be necessary.
  3. Making a life change exercise wise is often easier than making a life change eating wise. Implementing exercise may be ~three times a week. Or, even if it’s seven days a week, it’s usually max an hour a day. Changing eating is an everyday job, multiple times per day. For some, it overwhelms their mind damn near all day in the beginning. Some have dreams of breakin’ off a piece of a KitKat bar. It makes sense to start with the potentially easier change.

After around a month, you can usually tell what type of person you are. The weight is coming off or it isn’t. If it isn’t, it’s time to start the eating adjustments as well.

While our crazy pinks above may suggest some will start exercising and in a few months look like an Inuit powerlifter, I’ve never seen someone who in only a month or two gained a ton of weight once they started exercising. (Excluding those who explicitly wanted to do this e.g. American football players.) Sometimes a few pounds, but that’s about it. I think four is the max I’ve seen, and that was a guy who used to seriously work out, who started lifting again. Some muscle memory was probably going on there. I’ve also never seen someone whose appetite was chronically ravaging after exercise. Where exercise was genuinely an impediment to losing weight.

-> My assumption with the pinks above is that effect wanes over time. Much like you won’t turn into an Inuit powerlifter, you’re probably not going to turn into an Ethiopian marathoner either.

The pinks may have been an aberration too. With a lot of the subjects being students, one may have been hungover one day, feeling sick, and didn’t want to eat much. Or one was low on cash that week and thought, “Hey, free food!” (However, there were other subjects not too far from the pinks. They aren’t that much of an outlier.)

One way or another, it’s fairly rare to see someone start exercising and the weight flies off, where zero concern of food can be had, forever. And again, I’ve never seen someone start exercising who needed to buy a new wardrobe because of how big they got from it.

Even if this did happen, what I bet you can do is change the type of exercise rather than eliminate it. An example being move from aerobic to anaerobic. For some, a long walk may stimulate appetite, but going from burpees to push-ups to planks over and over again will not. Some, the converse may work. I’ve never had to do this either though, and, the moment you start suggesting someone not walk as much, you need to seriously consider what you’re saying. Should this person be manipulating their exercise, or themselves?

You should always be moving, but you don’t always need to change how you’re eating…but many of us do.

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