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Scientist busts myths about how humans burn calories

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Re: Scientist busts myths about how humans burn calories

#551

Post by JeremyNT »

rdiddly wrote: post #312

Last thing I saw was "The son of two high school English teachers, Pontzer grew up on 40 hectares of woods in the Appalachian bla bla bla..." You know that sentence. So many articles have that sentence. The one where it veers off course to talk about the (usually uninteresting) person who found the thing the article is ostensibly and nominally about. Am I alone in being perfectly happy reading about science for the d…

Yeah, this is a really strange article. It reads more like a human interest story about this one scientist's bio, with his work sprinkled in.

I'm not a fan of this style of reporting. It can be interesting to learn about a person's life if the subject is especially notable, but given the headline it feels a little like a bait and switch.

Re: Scientist busts myths about how humans burn calories

#552

Post by balfirevic »

KennyBlanken wrote: post #94
geoduck14 wrote: post #70

Earlier quoted context omitted.

>A lot of people know this already, so it’s not busting everyone’s myths It is still worth mentioning - because it is so easy to overlook. Some simple math: if I go all out on a row machine for 30 minutes, I'll burn 300 calories. If I eat 2 extra slices of pizza, it is easiely 300 calories If I swap a turkey sandwich with healthy options, I can reduce my linch calories by 300 - and I can save even more during dinner…

A few hours on my bike can be 2,000-3,000 additional calories over base metabolic rate. That's not based on made-up calories but actual work from a power meter on the bike. "You can't exercise your way out of a bad diet" - literally not true for a fuckton of endurance-sport athletes for whom the challenge is eating enough calories. It's 100% true for people who think exercising for 30 min means license to eat whateve…

> A few hours on my bike can be 2,000-3,000 additional calories over base metabolic rate.

Are you sure? 2000 kcal in 3 hours is 770 watts of power output.

Edit: Wikipedia [0] says "During a bicycle race, an elite cyclist can produce close to 400 watts of mechanical power over an hour and in short bursts over double that - 1000 to 1100 watts; modern racing bicycles have greater than 95% mechanical efficiency. An adult of good fitness is more likely to average between 50 and 150 watts for an hour of vigorous exercise."

[0] - https://en.wikipedia.org/wiki/Human_power

Re: Scientist busts myths about how humans burn calories

#553

Post by curiousllama »

artdigital wrote: post #457
wcrossbow wrote: post #430

Earlier quoted context omitted.

For me at least it's not that simple. My weight (healthy to low BMI) has been very stable over many years with vastly different amounts of exercising and quality of eating habits within that period. Fat to muscle ratio does move but total weight is stuck even with long runs of lots of junk food.

Hmm I have trouble believing that. If you eat less and put yourself into a caloric deficit, your body is going to start using up fat and to a certain degree muscle, that's just how it works and your body is no exception. If you work out during a deficit, your body will try to retain muscle and use more fat instead. Gaining muscle in a deficit is possible, but only in small amounts, if at all. > quality of eating habi…

The key is “fat to muscle ratio”

It’s a body recomp from an untrained person. Pretty common for new lifters.

You’re right though - if they lift better and eat better, that’ll change.

Re: Scientist busts myths about how humans burn calories

#554

Post by scotty79 »

nckthrn wrote: post #536
scotty79 wrote: post #514

Earlier quoted context omitted.

> If I bike for an hour I burn 700-1000kcal . Thats not 15 but 50% of the dayli calorie intake… That's estimated and probably impossible. 1000 kcal is 4184000 joules, divided by 3600 it gives you around 1100W Human at rest burns about 100W. Pro-cyclist can do additional 400W. There's no way you can burn energy at the rate of 1.1kW consistently for an hour unless you literally set yourself on fire. EDIT: I was wrong.…

Cycling is only approximately 25% mechanically efficient, so the parent is correct. There's a lot of heat to get rid of.

Apparently 700kcal burned per hour of cycling is a pretty realistic number.

https://www.welovecycling.com/wide/2020/05/14/how-to-convert...

Also resting kcal burn might be around 1800 per day. So 40% increase in of calories burned by hour of cycling per day every day is achievable.

The question is how can you breathe out additional ~10h of CO2 within an hour?

3 times deeper breathes 3 times faster? Because that carbon has to go somewhere.

Re: Scientist busts myths about how humans burn calories

#555

Post by scotty79 »

stedaniels wrote: post #490
scotty79 wrote: post #441

Earlier quoted context omitted.

Think about it this way. The rate at which you burn calories is directly proportional to the rate at which you breathe out CO2 because that what happens with carbon you burn. So if every day you train for an hour so that your breathing is 3 times faster, then you have additional two hours of burning in a day. 23 usual hours plus one worth 3. So you have 26 instead of 24 hours in a day. It's way easier to put 15% less…

You are arguing a different point. They argued that doing exercise burns more calories than sitting idle. @1_player said: > Your body burns incredibly more energy just "being there" than you burn moving about.

I was objecting to the word "incredibly".

Re: Scientist busts myths about how humans burn calories

#556

Post by tremon »

y4mi wrote: post #266
ajuc wrote: post #192

Earlier quoted context omitted.

Yes counting calories is essential, I had very similar experience (walk 10 km on the weekend ~= burn 600 kcal, then buy a 1000 kcal snack on the way back and wonder why I'm not losing weight), but still the exercise makes a big difference. Last year in march I started counting calories, recording my weight and all exercises I did and walking/biking every day. I lost 30 kg, walked 2100 km, biked 1000 km, and the sum o…

And yet the article you're commenting on says that you don't burn more calories by exercising... If it is true, it definitely changes the narrative.

Anecdotally, this has been my experience as well. I tend to think of my base metabolic rate as the integral over my physical activity over the last N years (it used to be N=5, but even that window is way too small I think now). Point being, you can be inactive for a long time without a meaningful change in body fat/weight, but eventually your body adjusts. Or rather, the first gain in body fat is offset by the loss of muscle weight. Once you're at a slower metabolic rate and less muscle, exercise becomes more difficult and it takes years of consistent activity to raise your metabolic rate again.

I'm not sure how base metabolic rate relates to incidental energy expenditure. My gut feeling is that every body has its own limits on energy expenditure, and max TDEE doesn't need to correlate directly with base metabolic rate. That's why I mentioned the integral above. I tend to think of $TDEE_{max} \simeq MBR_{base} + E_{available}$ but $MBR_{base} \simeq \int_{t=-5}^0 TEE(t)$ -- and in my experience, weight loss correlates more with base metabolic rate than with caloric intake ($E_{available}$).

Re: Scientist busts myths about how humans burn calories

#557

Post by maxerickson »

scotty79 wrote: post #554
nckthrn wrote: post #536

Earlier quoted context omitted.

Cycling is only approximately 25% mechanically efficient, so the parent is correct. There's a lot of heat to get rid of.

Apparently 700kcal burned per hour of cycling is a pretty realistic number. https://www.welovecycling.com/wide/2020/05/14/how-to-convert... Also resting kcal burn might be around 1800 per day. So 40% increase in of calories burned by hour of cycling per day every day is achievable. The question is how can you breathe out additional ~10h of CO2 within an hour? 3 times deeper breathes 3 times faster? Because that carbo…

The CO2 concentration going up in the blood increases the efficiency of respiration (because it is ultimately diffusion).

You don't necessarily need to exchange 10 times the volume of air to deal with the additional CO2.

Re: Scientist busts myths about how humans burn calories

#558

Post by [deleted] »

mantas wrote: post #485
me_me_me wrote: post #472

Earlier quoted context omitted.

I don't get it, how is that a myth or controversial. Cutting empty calories is the easiest to remove calories from daily total. Exercise further decreases the ratio of calories in calories out. Bottom line is: calories in - calories out. There are caveats there for sure, like increasing muscle mass increases idle caloric burn. Different types of food have different effect promoting or impeding metabolism.

Guess what else has massive effect on metabolism? Exercise. Also, various workouts have a lot of other important effects. Increasing bone strength, improving body resistance to inflammatory processes, developing micro vascular system… simply managing calorie in/out ratio won’t get you any of this. And dropping weight in a dumb way may do more harm than good.

[deleted]

Re: Scientist busts myths about how humans burn calories

#560

Post by mantas »

marcus_holmes wrote: post #522
mantas wrote: post #458

Earlier quoted context omitted.

> Your body burns incredibly more energy just "being there" than you burn moving about. Bullshit. My body goes through 1600-ish kcal on an idle day. If I go out on a 4h steady bicycle ride (= 100km), I go through 2000 kcal on ride alone. That’s much more than my body burns just being there.

Did you read the article? because this specific thing is what the science that the article covers explains. tl;dr: your body burns roughly the same amount of calories regardless of exercise. However, it allocates those calories differently: if you don't spend them on exercise then it will spend them on stress (and presumably other stuff). Which totally makes sense as to why my depression & anxiety fade if I run or wo…

Depression and anxiety fades because endurance exercises release certain hormones and help to flush out kortizol.

And yes, it allocates calories towards building fat. Which is a weeeee different from burning them.

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