Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

People with low BMI aren't more active, they are just less hungry, 'run hotter'

sciencedaily.com

Post reply on HN
Print view View original

71–80 of 350 posts

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#71

Post by JacobThreeThree »

sleepydog wrote: post #46
the_only_law wrote: post #35

Seems to line up with my experience, am always burning up (until I turn on the AC and freeze) Especially at night though I have to to jack the temperature down or I won't sleep. Also less hungry aligns pretty well. Unfortunately when I get hungry, it's normally "a little hungry) at akward spread out intervals. I probably feel most hungry after midnight but never eat then because well, I have to sleep soon. I've tried…

If you run hotter, wouldn't you feel less hot? Since your normal temperature would be that much higher than the ambient temperature. At least, when I have a fever I feel cold, even though I'm hot.

It seems like the study used metabolic rate (energy/time unit) and thyroid activity, not body temperature. That being said, metabolic rate probably correlates with body temperature, but that's not clear.

What's interesting is that these people kept a high metabolic rate while doing less activity. It's almost like, if you rest more, your body will have the energy to increase its metabolic rate, or it could be totally physiological and it depends on the person.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#72

Post by marifjeren »

giraffe_lady wrote: post #52

If I were playing a game of trying to extrapolate HN titles by the comment sections, my guess for this one would be "Ask HN: What's your BMI and what does that say about you"

Thank you for asking. My BMI is 31 and it's because I eat too much.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#73

Post by the_only_law »

giraffe_lady wrote: post #52

If I were playing a game of trying to extrapolate HN titles by the comment sections, my guess for this one would be "Ask HN: What's your BMI and what does that say about you"

Instead we get boring meta comments.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#74

Post by zhynn »

sudden_dystopia wrote: post #42

The study was underweight bmi vs healthy bmi. Nothing about overweight bmi, which I would assume is the trifecta of overeating, little activity, and slower metabolism. At least that is my personal experience in going from overweight to healthy bmi. Really not surprising that people that eat less have lower bmi and higher metabolism than people that eat more with a slower metabolism but who are more active.

you missed the important point, IMO: being hungry. it's bizarre that we can be mechanically and nutritionally full yet still be hungry. These low BMI individuals were not hungry.

WTF is going on with the hunger response being so messed up in a huge segment of the population?

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#75

Post by sgt »

FollowingTheDao wrote: post #43
sgt wrote: post #40

Earlier quoted context omitted.

Samis are also pretty small people. Almost like elves. That can actually be an advantage for longevity in some ways.

Yeah, we are all short stature as well. If fact, my older brother was given growth hormones as a young child because he was not "growing as expected". Idiots. All Inuit populations are shorter on average.

That's terrible! Hope they put an end to that.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#76

Post by windowsrookie »

the_only_law wrote: post #35

Seems to line up with my experience, am always burning up (until I turn on the AC and freeze) Especially at night though I have to to jack the temperature down or I won't sleep. Also less hungry aligns pretty well. Unfortunately when I get hungry, it's normally "a little hungry) at akward spread out intervals. I probably feel most hungry after midnight but never eat then because well, I have to sleep soon. I've tried…

Interesting. I stay thin because I'm always watching what I eat and keep a mental note of how many calories I've had that day. If I'm trying to lose a few pounds I have to actually record my calories so I know when to stop eating.

I can eat pretty much non-stop. I could eat a large pizza myself, and 30 minutes later eat another.

The grass is always greener. Some people wish they could eat as much as me so they could gain some weight. I wish I couldn't eat so much so I didn't have to spend so much mental energy on ensuring I don't over-eat.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#77

Post by csours »

Hunger is mediated by a bunch of hormones and you can test for some of those, but there is no test for the feeling of hunger. As a comparison, it is famously very hard for doctors to understand pain; it is also difficult for patients to communicate about pain.

The feeling of hunger is not comparable between people. Hunger is driven by multiple sensations (blood sugar, stomach stretch, hormone levels) and by cognitive behaviors (it's lunchtime, it's a feast day) and psychological conditioning (advertising). People have relationships with, and expectations about food. The response to hunger is learned. It is driven by culture - for instance it is 'manly' to eat a large steak and loaded baked potato where I'm from; many times the smaller cuts of steak have either a woman's name or some feminine aspect.

Scientists use Occam's Razor to find the most probable cause for some effect, and people in general want to find something simple to blame. I think the obesity epidemic has many causes, and it is particularly hard to understand because researchers have only lately begun to take hunger seriously. It is easy to say "Diet and Exercise" but losing body fat means that you must continuously make choices that decrease your comfort in some way - eating fewer highly rewarding foods, maintaining a state of hunger, increasing activity level. Those choices are difficult, and they are different for everyone.

I believe there are many consequences of the difficulty in measuring and tracking hunger. I think that many people (including doctors and researchers and HN users) want to be able to change one thing or add one drug and suddenly solve the obesity epidemic. I think it makes it hard for doctors to talk to patients. It makes it hard for people to understand what their body is doing.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#78

Post by dilap »

There's a really interesting study they did with pigs.

They fed pigs four different diets that had the same amount of calories, but varying ratios of n3/n6 fats.

The pigs with high n6/n3 ratio ended up much fatter and less muscular than the pigs eating a 1-1 ratio diet. It's a very neat demonstration that "all that matters is calories" is not true; your metabolism, and thus how you use the calories, is influenced by the kinds of calories you are eating.

Well, at least if you are a pig. But it seems likely the same holds true in humans, though AFAIK no one has yet tried to do a similar controlled trial in humans.

But there's lots of assocational evidence that lines up in the same direction -- e.g., in America we've been getting fatter pretty much in-lock step with increasing consumption of n6 fats & there is a correlation between body-fat composition (which itself follows fat composition from the diet) and obesity.

So, in the light of the above, my #1 weight loss tip is: eat fewer n6 fats. (In practice, this means avoiding most prepared processed foodes and being extremely selective if eating out (since restaurants tend to go crazy using vegetable oil as a cooking fat, which is super high in n6 fats).)

The pigs study:

https://www.cambridge.org/core/journals/british-journal-of-n...

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#79

Post by derefr »

sleepydog wrote: post #46
the_only_law wrote: post #35

Seems to line up with my experience, am always burning up (until I turn on the AC and freeze) Especially at night though I have to to jack the temperature down or I won't sleep. Also less hungry aligns pretty well. Unfortunately when I get hungry, it's normally "a little hungry) at akward spread out intervals. I probably feel most hungry after midnight but never eat then because well, I have to sleep soon. I've tried…

If you run hotter, wouldn't you feel less hot? Since your normal temperature would be that much higher than the ambient temperature. At least, when I have a fever I feel cold, even though I'm hot.

Feeling cold in a fever is a specific lie your brain tells your body, to trigger shivering, so that your skeletal muscle will help to heat you up even faster. Usually, when you're hot, you feel hot.

Re: People with low BMI aren't more active, they are just less hungry, 'run hotter'

#80

Post by frostwarrior »

FollowingTheDao wrote: post #66
ianbutler wrote: post #48

Does this breakdown when you gain weight? Like when I was 20 I weighed 180lbs of solid muscle and was always like a furnace. Then I slipped a disk and now at 28 I'm lucky if I hover around 240 (I've actually been back lifting for the last 2.5 months and feel pretty good) but I definitely feel like I run colder in general now that I'm overweight.

Gaining muscle mass will often lead to a quick onset of obesity once you stop lifting.

Yes but this looks more like habit disruption more than "biologically gaining weight somehow".

People that lift often eat more. But mostly protein, and stimulating muscle every day makes sure it will get developed and consume more calories to maintain itself.

If you stop lifting altogether, not only muscle mass stops growing but also starts to shrink. If you eat the same, you will gain weight faster and with less food than before.

Post reply on HN