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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

#611

Post by scotty79 »

maxerickson wrote: post #590
scotty79 wrote: post #575

Earlier quoted context omitted.

Range given for concentration of CO2 on exhaled air is 4-5% So it looks like it could be 25% difference at most.

I doubt the 4-5% you saw is a first principle of breathing.

Why not? CO2 levels in blood must be tightly controlled. It probably can't get twice as high as usual.

If there's already 4% of CO2 in the air around you it's an immediate danger. While you can spend 10 minutes in 3%. If your body could bump up CO2 in exhaled air from 4% to 8% then you'd probably have bo problem surviving in air thay contains 4%.

Re: Scientist busts myths about how humans burn calories

#612

Post by 0xcde4c3db »

Aachen wrote: post #540
pwrrr wrote: post #483

"You can't burn calories. Calories is a measure of heat. You can't burn heat." - Bart Kay CICO, Calories in/Calories out also doesn't work like that in the human body, because the human body is not a closed system. https://www.youtube.com/watch?v=crA0MLKleBQ

In that case, explain to me how my house gets warm from burning caloric gas ... calories are obviously the measure of how much heat you get from burning something, not the heat itself that you're "burning"

> calories are obviously the measure of how much heat you get from burning something, not the heat itself that you're "burning"

I think that's exactly the point: calories can only measure how much we're burning, but what we're burning matters just as much, if not more. If your gas service was cut off, you would (I hope) not pump crude oil into your furnace instead. It might be accurate (as far as it goes) to say that a furnace is a machine for turning hydrocarbon fluids into heat, but you probably respect your furnace and its requirements too much to do something like that. Most people, including too many exercise and nutrition "experts", are all too happy to make oversimplifications nearly as silly when thinking about our own bodies.

Re: Scientist busts myths about how humans burn calories

#613

Post by nsxwolf »

ch4s3 wrote: post #77
nsxwolf wrote: post #36

This is very depressing. I find it incredibly difficult to lose weight dieting. And now it's telling me I just wasted all this money on a treadmill (and the effort it took to get it down into the basement).

Cardio is great for general health, and cannelloni shave off a few extra calories even once you’re good at it. Buy some weights, and put on a few pounds of muscle. The muscle costs more calories to maintain, so for your same diet you can shift you body composition a little. For a beginner you can see a lot of results in about three lifting sessions a week in only a handful of weeks.

Were you trolling me with delicious cannelloni there? :)

Re: Scientist busts myths about how humans burn calories

#614

Post by uberduper »

lhuser123 wrote: post #88
PaulDavisThe1st wrote: post #72

Earlier quoted context omitted.

> 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…

I have a bias towards the idea that we are very different, and it really depends on many unknown factors that apply only to one specific individual.

We're not _that_ different. And a lot _is_ known. There isn't anyone on earth with incurable obesity.

Re: Scientist busts myths about how humans burn calories

#615

Post by InitialLastName »

aixi wrote: post #375
Elte wrote: post #321

Earlier quoted context omitted.

I'm a bit confused by this point in the article, because it also states: > There seems to be a hard limit on how many calories our bodies can burn per day, set by how fast we can digest food and turn it into energy. He calculates that the ceiling for an 85-kilogram man would be about 4650 calories per day. Given that "regular" people clearly do not burn 4650 calories per day, and it is possible to burn 4650 calories…

out of context, that quote is really funny; what happens once you reach 4650 calories? you start violating the rules of thermodynamics? (i know your body starts compensating for it and burning less calories, but still)

At some point your body will also fail to exert energy; there are also metabolic safeguards ahead of the point where your body can no longer manage the energy to keep basic functions going where the lower-priority functions (immune system, cognitive function, motion muscles) start to degrade.

You don't need to be at the limit of human energy intake to see what happens to people when their energy expenditure greatly exceeds the energy available from food over a sustained time period; there is quite a lot of medical literature on the effects of such... er... malnutrition.

Re: Scientist busts myths about how humans burn calories

#616

Post by NoboruWataya »

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…

It's definitely true that eating less/healthier is the most important part of weight loss. However, perhaps because exercise played a big role in my own weight loss journey, I do feel like people go too far in dismissing it as a weight loss aid.

First of all, while a 3k run isn't going to do much to burn off that slice of cake you had with lunch, if you transition from a generally inactive lifestyle to a generally active one (eg, by getting into running as a hobby), you can cumulatively burn a decent amount of calories. Cardio as a hobby is not for everyone, but I thought it wasn't for me until I gave it a shot and found I really enjoyed it.

There are also psychological advantages of incorporating exercise into a weight loss regime. I started eating better after, and partially because, I started exercising. When you work out a lot, you start to enjoy feeling healthy (or at least, thinking of yourself as a healthy person), and you start to realise that junk food is working against that.

Finally, weight loss should not be your only goal if you are interested in getting healthier. It's true that you could lose weight by being very sedentary and eating very little, but I suspect that would bring its own health problems.

Re: Scientist busts myths about how humans burn calories

#617

Post by dahart »

aixi wrote: post #375
Elte wrote: post #321

Earlier quoted context omitted.

I'm a bit confused by this point in the article, because it also states: > There seems to be a hard limit on how many calories our bodies can burn per day, set by how fast we can digest food and turn it into energy. He calculates that the ceiling for an 85-kilogram man would be about 4650 calories per day. Given that "regular" people clearly do not burn 4650 calories per day, and it is possible to burn 4650 calories…

out of context, that quote is really funny; what happens once you reach 4650 calories? you start violating the rules of thermodynamics? (i know your body starts compensating for it and burning less calories, but still)

> what happens once you reach 4560 calories?

There are loads of videos on YouTube of what happens. You may or may not want to watch them. Spoiler alert: you vomit when you eat too much.

The vomit limit is probably higher than 4560 (which BTW has a suspicious number of significant digits), there might be a range between too many calories and vomiting where your body breaks down the food into waste without digesting any more nutrients/calories. Kinda like how if you eat too much vitamin C, you’ll just pee most of it out.

Re: Scientist busts myths about how humans burn calories

#618

Post by e40 »

cagmz wrote: post #237
e40 wrote: post #186

Earlier quoted context omitted.

Fasting isn’t a mood killer, it actually has the opposite effect. IF gives me an energy boost and associated euphoria.

What is your IF schedule like? Can you expand on the euphoria?

When I do 24 hr fasts (going from dinner to dinner), which is not that often, in the early afternoon until dinner time I get a big energy boost and very enhanced mood. That first time, I thought that it felt like I was high on something.

Re: Scientist busts myths about how humans burn calories

#619

Post by louis___ »

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…

> we also do have a strange narrative surrounding exercise and weight loss that I bought into

This narrative is pushed by the fast and highly-processed food industry. MacDonalds is sponsoring sport events with that very narrative : "morbidly-obese children of 8 should just do a bit more sport"

Re: Scientist busts myths about how humans burn calories

#620

Post by naasking »

alistairSH wrote: post #585
hgomersall wrote: post #392

Earlier quoted context omitted.

Yeah, I thought this. There's clearly an amount of exercise that will cause you to lose weight. An interesting question is whether your body prevents you from achieving that. Cycling was always interesting to me in this context because it seems easier to burn energy on a bike than other forms of exercise.

seems easier to burn energy on a bike than other forms of exercise I'm not sure this is true. Cycling isn't weight-bearing (you're sitting down) and only engages the large leg muscles. Running and rowing likely provide more calorie burn for a given RPE (rate of perceived exertion) over a fixed time period. Running because it's weight-bearing; rowing because it engages more muscle groups. That said, you can probably c…

Running doesn't burn as much as you think because your muscles store energy elastically on the eccentric phase of each step. This removes a lot of energy needed for the subsequent concentric part.

Contrast this with cycling which is pretty much all concentric contractions.

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