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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

#511

Post by bern4444 »

dahart wrote: post #4

> “You can’t exercise your way out of obesity,” […] “you can’t outrun a bad diet.” While this article is being a bit dramatic and possibly understating the impact of exercise slightly, I feel a little dumb that I didn’t know this earlier. It took me several decades too long to understand the obvious, that exercise is for building strength, and losing weight happens by eating less. I tried for way too many years to ex…

From my own experience, if I'm lifting weights and working out, my hunger shoots up and I start wanting to eat everything in sight.

When I'm not working out regularly, I'm able to eat far less in a day and feel totally full. By not working out, I'm able to eat far fewer calories and actually lose more weight. Drinking lots of water (64 - 96 oz) a day also helps a lot.

Re: Scientist busts myths about how humans burn calories

#512

Post by tgb »

scotty79 wrote: post #441
jeltz wrote: post #404

Earlier quoted context omitted.

While I agree with that excerice isn't a very efficient way to lose weight I think that you understate how many calories running burns. When I run consistently I need to eat what feels like a lot more food to maintain my weight. Running burns about 700-800 kcal per hour for me (I have a quite small build) which ends up quite a bit over a week (I run 5-8 hours per week).

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're assuming that breathing rate is proportional to CO2 breathed out, which I doubt. I barely breath any faster while running than while just sitting here, much less than 3x.

Re: Scientist busts myths about how humans burn calories

#513

Post by watwut »

CJefferson wrote: post #475
jeltz wrote: post #404

Earlier quoted context omitted.

While I agree with that excerice isn't a very efficient way to lose weight I think that you understate how many calories running burns. When I run consistently I need to eat what feels like a lot more food to maintain my weight. Running burns about 700-800 kcal per hour for me (I have a quite small build) which ends up quite a bit over a week (I run 5-8 hours per week).

The problem is, it isn't efficient if you are overweight :) When I was at my heaviest weight, I could only do a normal-speed walk, which burned relatively little calories. At my lightest, I was also having to go out of my way to eat extra calories, as I was cycling so much, and a fast 90 minute cycle would leave me light-headed if I didn't eat some extra calories.

This is primary that thing where exercising makes you more fit and in the long term more active in general. Because what was previously tiring straining activity suddenly becomes pleasurable. And if you eventually manage to stumble upon activity you actually like, it is way easier to do it then to sit at home hungry, passive and obsessed about how miserable you feel (until said person will break and eat a candy or something similar).

Re: Scientist busts myths about how humans burn calories

#514

Post by scotty79 »

bratwurst3000 wrote: post #451
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…

Yes but in numbers it is way more. If I bike for an hour I burn 700-1000kcal . Thats not 15 but 50% of the dayli calorie intake… i am no expert btw. My understanding is that the problem is more that after 20 minuts of sport, at a certain heart rate, is starting to burn fat…but not body fat. More free floating fat. And it takes one hour or so to start burning bodymass. So the fuel for one hour sport is what I ate befo…

> 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.

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

#515

Post by cataphract »

watwut wrote: post #420
episteme wrote: post #411

Earlier quoted context omitted.

This is not accurate, weightlifting with a reasonably difficult weight for your strength level is one of the most effective ways to burn calories.

> This is not accurate, weightlifting with a reasonably difficult weight for your strength level is one of the most effective ways to burn calories. It wont make you loose weight however. It will likely make you gain weight as your muscles will grow. Which is explicit goal of many guys who start lifting weights.

I think that this depends on your training regimen. You can train for strength, not muscle mass. This is especially important for some athletes, like cyclists, where extra weight is a liability (more mass for the same force means less acceleration).

When the gyms closed for the pandemic, I lost 5 kg of muscle. After coming back, I started doing fewer sets and have not regained the muscle mass. But my strength (the amount of weight I can lift) is now very close to pre-pandemic levels.

Re: Scientist busts myths about how humans burn calories

#516

Post by MayeulC »

PaulDavisThe1st wrote: post #72
_9omd wrote: post #65

Earlier quoted context omitted.

I think a big part of the issue is that popular fitness and weight loss advice has perpetuated the wrong way to exercise to loose weight. When most people think about exercise for weight loss, they imagine long exhausting sessions on the treadmill, dripping with sweat, and a high calorie burn number. While the short term results may seem great based on the immediate calories burned, it's actually a terrible strategy…

> 2) Your hunger will increase to compensate for the calories burned and you'll subconsciously eat more if not carefully tracking. This is also a oft-made claim that doesn't have much backing. Part of the point of the research described in TFA is that humans who face specific periods of energy expenditure during the day may often simply reduce energy expenditure during the rest of the day so that TEE remains roughly…

If you are low on sugar (therefore hungry) for a while, your body will start burning fat (lipolysis) to restore sugar levels. This will suppress apetite.

It's easy to experience, although it can take longer for lipolysis to start if you're not used to. Of course, eating sugar during or before exercise delays it.

Re: Scientist busts myths about how humans burn calories

#517

Post by tgb »

antman wrote: post #425
oblio wrote: post #384

Earlier quoted context omitted.

> If I start lifting 20lbs and 3 years later I still lift that of course I won't lose weight. This example is kind of bad :-) You don't lose weight by lifting weights, in general. And amusingly, if you did want to lose weight by lifting weights, your example is precisely how you > lose weight. You lift 10kgs over and over and over again, or even better, incorporate the extra weight into some sort of cardio routine. I…

One does not only lose weight because of the exercise itself, but by retaining muscles since they are a major calorific expenditure factor. Large mass muscles burn calories e.g. glutes

Sadly, muscle only burns 12.6 kcal / kg /day at rest [1]. If you put on an impressive 20kg of muscle that would only increase total expenditure by 250 kcal a day. If you want your muscles to burn calories, you'd better be exercising them.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2980962/

Re: Scientist busts myths about how humans burn calories

#518

Post by scotty79 »

tgb wrote: post #512
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're assuming that breathing rate is proportional to CO2 breathed out, which I doubt. I barely breath any faster while running than while just sitting here, much less than 3x.

It is directly proportional because of how lungs work. The percentage of CO2 in exhaled air is roughly the same regardless of how fast you are breathing (if you don't artificially accelerate your breathing beyond what your body dictates).

Lungs can't put in more CO2 in breathed out air.

If you breath only slightly faster when you are running than when you are sitting that must mean you ran quite a lot and optimized your stride so that you don't burn much more calories running than sitting.

But more likely explanation is that you are not aware how fast exactly you are breathing when sitting and running. Try to measure it. Also take into account that you might be taking shallower breaths when you are sitting.

Just blow up a balloon when you are sitting and when you are running with your normal exhaled breath for few seconds to test it.

Re: Scientist busts myths about how humans burn calories

#519

Post by Xcelerate »

akeck wrote: post #492
Xcelerate wrote: post #487

The article seems to miss what is (at least to me) the most interesting follow-up question: if exercise doesn’t cause a person to burn significantly more Calories throughout the day to induce weight loss, then what does? I’m somewhat hard-pressed to believe the answer is diet alone. Anecdotally, when I was running 100 miles per week in college for cross country, I ate three or four giant meals per day and maintained…

If I recall correctly, capital "C" Calorie, used in nutrition, is another term for kilocalorie. Lowercase "c" calorie is the SI unit. 1 kcal/Calorie is 1000 calories.

That’s correct. I used a lowercase “c” for (kilo)calorie to highlight that explicitly, but capital “C” elsewhere.

Re: Scientist busts myths about how humans burn calories

#520

Post by jghn »

irthomasthomas wrote: post #508
tlamponi wrote: post #503

Earlier quoted context omitted.

> calories in - calories out was debunked a while ago. Not really, it's just that calories-in is worst-case that's what's on the foods box, you cannot magically produce more energy but it's well known that not everything can be processed by the metabolism with the same efficiency. So with extremes like your example the difference is naturally huge, but that doesn't matter in practice if one balances their consumption…

Not really. E.g. look at my second example, cold potatoes vs hot potatoes. Same calories, same exact ingredients, but hot potatoes are significantly worse than cold potatoes. I dont have the link to hand, but there is a GL database maintained by Harvard, I think, that demonstrates this. I will look it up later for you.

It’s still calories in vs calories out. What changed is that our understanding of what determines calories in and calories out has become more nuanced. For instance, your examples
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