Is there a calorie burning "plateau"?

amusedmonkey

I came across an interesting article. It suggests that increasing habitual physical activity beyond a certain point does not show a linear relationship with calorie expenditure, and that after a certain point the body starts reducing the calories burned by other mechanisms to conserve energy. What does this mean for certain people who are considered very active in terms of eating back exercise calories?

http://www.cell.com/current-biology/fulltext/S0960-9822(15)01577-8

Any personal experiences from people who regularly participate in endurance sports?

amusedmonkey

Bump

sheermomentum

I would say that it means that after a certain point, you should probably stop exercising so much, assuming the exercise is voluntary and not due to manual labor. Otherwise you may experience some undesirable adaptations in autonomic systems. The study also seems to indicate that many people will automatically try to compensate for the high level of activity by moving less when they don't have to. I.E. they're tired; they sit down more. We should note, however, that the subjects in this study were normal-weight individuals.

As far as eating back exercise calories: its not 100% clear to me on the quick read that I've just done at what level of non-RMR energy expenditure this adaptation might begin to take place. So if you're asking if you (or anyone) might be experiencing this kind of adaptation, then I'd say if you are eating back a lot of exercise calories and not losing weight, or gaining when you want to maintain, then eat fewer exercise calories and see how that goes.

The_Enginerd

The activity was measured in CPM/day (counts per minute/day), using an accelerometer, basically an activity tracker. I can see there being some significant limitations to that method given that intentional exercise is usually done at a significant intensity per movement.

Personally, the additive approach has worked for me from relatively sedentary with just walking while on extended work travel all the way up to 60 MPW training for a marathon.

I can imagine there is a kink to total daily energy expenditure versus exercise activity as a person compensates for higher energy expenditure in one part of the day by being less active in another part of the day, and this would effect TDEE in a way that it wouldn't be simply additive, but I don't feel that it would "plateau" at any normal exercise level. And most folks are probably WELL below that kink.

L_Master

amusedmonkey wrote: »

I came across an interesting article. It suggests that increasing habitual physical activity beyond a certain point does not show a linear relationship with calorie expenditure, and that after a certain point the body starts reducing the calories burned by other mechanisms to conserve energy. What does this mean for certain people who are considered very active in terms of eating back exercise calories?

http://www.cell.com/current-biology/fulltext/S0960-9822(15)01577-8

Any personal experiences from people who regularly participate in endurance sports?

It's probably true to an extent but no way can it compensate for really serious training. In other words if you train a whole bunch, it makes sense that you would be less active during the day, reducing things like NEAT.

However, even if you were completely sedentary that difference is likely to be 200-300 calories at a minimum to maybe 800-1000 MAX. Which if almost nothing compared to say a 6 hour bike ride that burns 4,500 kcal.

amusedmonkey

The thing is, there is a steep decline in energy expenditure relative to activity happened after 200 CPM. They defined sedentary as <100 CPM, so 200 CPM is not even that far from what many active people could achieve. In terms of steps, sedentary is usually defined as <5000, so if they got it right, the usual recommendation of 10,000 steps would actually be the point where any further activity would have diminishing returns where any extra 5000 steps would only burn 50 calories. That's something to consider.

autumnblade75

I will tell you that in my experience, diminishing returns don't set in before 20,000 steps per day, and I'm not expecting them to set in before 40,000 steps per day, either. Not in terms of burning the expected number of calories, anyway. I do notice that the more time I spend on the treadmill, the less I move when I'm not actively exercising. But my observations suggest that my Fitbit's estimations hold true up to 60,000 steps per day (not that I have what it takes to achieve that level of activity for multiple days in a row...) so I'm not particularly worried about the "study."

Azdak

I think this is one of those "needs to be taken seriously, but calls for further investigation" studies. Meaning: there are valid points raised, but cannot overgeneralize at this point.

Certainly the idea that increased exercise (or work) activity can result in a associated decrease in casual activity is well known. In fact, it's one of the chief arguments against the idea of logging casual activities like housework, cleaning, washing the car, etc, as "exercise".

As far as long-term metabolic adaptations--those could happen, but it will take a lot more research to determine the extent. We do know that long-term endurance training increases parasympathetic tone, perhaps to a permanent degree.

However, as an n=1 sample, I know that, after 40 years of on/off aerobic endurance exercise (and 56 pound wt loss in 5 months) my resting metabolic rate exactly matched the estimated amount for my age, height, weight, and gender. And my tested metabolic response to vigorous exercise was within the expected margin of error for the energy prediction equations for workload I was performing.

I think this study suggests that there is a limit to the postive effects of increasing exercise, and this is also something that is not a big revelation. So, the takeaway IMO, is that one should not expect exercise to be a lifelong cure-all for weight control.

MelodyandBarbells

I scanned the article over a couple times, so I'm not sure if this was clarified. What was the duration of the studies (different locations around the world, it looks like), and did the subjects lose weight, possibly accounting for reduction in TDEE?

I've exercised for up to three hours at a time, and seemed to lose weight at the expected pace. Mostly I max out at two hours, and other than getting from A to B and trying not to be lazy about moving around, I don't intentionally try to get a lot of steps

cwolfman13

Azdak wrote: »

I think this is one of those "needs to be taken seriously, but calls for further investigation" studies. Meaning: there are valid points raised, but cannot overgeneralize at this point.

Certainly the idea that increased exercise (or work) activity can result in a associated decrease in casual activity is well known. In fact, it's one of the chief arguments against the idea of logging casual activities like housework, cleaning, washing the car, etc, as "exercise".

As far as long-term metabolic adaptations--those could happen, but it will take a lot more research to determine the extent. We do know that long-term endurance training increases parasympathetic tone, perhaps to a permanent degree.

However, as an n=1 sample, I know that, after 40 years of on/off aerobic endurance exercise (and 56 pound wt loss in 5 months) my resting metabolic rate exactly matched the estimated amount for my age, height, weight, and gender. And my tested metabolic response to vigorous exercise was within the expected margin of error for the energy prediction equations for workload I was performing.

I think this study suggests that there is a limit to the postive effects of increasing exercise, and this is also something that is not a big revelation. So, the takeaway IMO, is that one should not expect exercise to be a lifelong cure-all for weight control.

pretty much this...

snickerscharlie

Azdak wrote: »

I think this is one of those "needs to be taken seriously, but calls for further investigation" studies. Meaning: there are valid points raised, but cannot overgeneralize at this point.

Certainly the idea that increased exercise (or work) activity can result in a associated decrease in casual activity is well known. In fact, it's one of the chief arguments against the idea of logging casual activities like housework, cleaning, washing the car, etc, as "exercise".

As far as long-term metabolic adaptations--those could happen, but it will take a lot more research to determine the extent. We do know that long-term endurance training increases parasympathetic tone, perhaps to a permanent degree.

However, as an n=1 sample, I know that, after 40 years of on/off aerobic endurance exercise (and 56 pound wt loss in 5 months) my resting metabolic rate exactly matched the estimated amount for my age, height, weight, and gender. And my tested metabolic response to vigorous exercise was within the expected margin of error for the energy prediction equations for workload I was performing.

I think this study suggests that there is a limit to the postive effects of increasing exercise, and this is also something that is not a big revelation. So, the takeaway IMO, is that one should not expect exercise to be a lifelong cure-all for weight control.

+2

stevencloser

I've heard that high level runners have resting heart rates of like 40 bpm, which would be a lower REE I guess.

sijomial

stevencloser wrote: »

I've heard that high level runners have resting heart rates of like 40 bpm, which would be a lower REE I guess.

More likely that endurance athletes are simply pumping more blood per heartbeat compared to less fit people.
a.k.a. stroke volume.

amusedmonkey

Thank you for sharing your personal experiences. It confirms what I already suspected, that more research is needed. It does put things into perspective though, another reason while activity alone may not be the best weight management solution, no matter how much of it.

The_Enginerd

amusedmonkey wrote: »

Thank you for sharing your personal experiences. It confirms what I already suspected, that more research is needed. It does put things into perspective though, another reason while activity alone may not be the best weight management solution, no matter how much of it.

The other issue is that hunger tends to increase in step with high levels of activity. And it is very, VERY difficult to outrun a fork. Even at 50 MPW, my TDEE is increased from 2300 when sedentary to ~3000. Some bigger portions or higher calorie food choices, a couple of treats/snacks during the day, and I've made up for those extra calories quite easily.

The_Enginerd

sijomial wrote: »

stevencloser wrote: »

I've heard that high level runners have resting heart rates of like 40 bpm, which would be a lower REE I guess.

More likely that endurance athletes are simply pumping more blood per heartbeat compared to less fit people.
a.k.a. stroke volume.

Yep, exactly. My RHR is over 10 BPM lower after several marathon training cycles, even though my sedentary calorie needs haven't changed.

Azdak

sijomial wrote: »

stevencloser wrote: »

I've heard that high level runners have resting heart rates of like 40 bpm, which would be a lower REE I guess.

More likely that endurance athletes are simply pumping more blood per heartbeat compared to less fit people.
a.k.a. stroke volume.

The effect is the same, but, if you are interested, I believe the mechanism is actually the increased parasympathetic activity. The increase in PS activity lowers heart rate--->lower heart rate results in increased left ventricular filling (Frank-Starling effect)---->increased ventricular filling increases stroke volume.

Like I said, the result is the same, but the mechanism is backwards. We (and I thought this too) like to think that it's the "stronger heart" that results in the lowered RHR, but it's actually the opposite: the CNS-lowered RHR results in the "stronger" (more efficiently pumping) heart.

Azdak

JaneiR36 wrote: »

I scanned the article over a couple times, so I'm not sure if this was clarified. What was the duration of the studies (different locations around the world, it looks like), and did the subjects lose weight, possibly accounting for reduction in TDEE?

I've exercised for up to three hours at a time, and seemed to lose weight at the expected pace. Mostly I max out at two hours, and other than getting from A to B and trying not to be lazy about moving around, I don't intentionally try to get a lot of steps

Research has shown for a long time that, when studied, actual weight loss achieved is almost always less than what would be predicted based on energy expenditure. There are some easy answers: many people underestimate their food intake and overestimate their casual activity; but it has also be shown to occur in studies where those factors are more controlled. Other reasons might be that the "3500kcal=1lb fat" assumption is overly simplistic, increase in thermal efficiency (increased energy absorption from food), or there are other reasons we don't know yet.

There are a lot of variables, which is why it takes multiple studies to even hint at definite reasons.