If heavier people have a higher BMR/RMR why do skinny people remain skinny without exercise?

This question has been plaguing me for awhile. I was once over 300 pounds and my BMR was something like 4,000 calories a day, but it is now at about 2,400. As I lose weight, I burn less calories throughout the day just living. So how do people who are 150 pounds or so and don't exercise and maintain an unhealthy lifestyle (I know plenty of them) remain so thin? Don't you burn less calories the skinnier you are? Shouldn't they be obese? Thanks in advance...

- Jon

They're just blessed. They have a metabolism that matches what they eat or are slow to put on weight.

Some people are just born lucky.

lots of things besides sizes factor into metabolism.  some skinny people seem inactive but really aren't; some are malnourished; some are sick.  some eat differently in public than they do in private.

there's no direct correlation between weight and BMR. and there's not much point pondering what "other people" do.

Well I am speaking from personal experience. I live with 4 other people, all of whom are in the healthy BMI range and are noticeably thin, and they eat junk food all day and are still skinny. Something has to give, its not magic. And trust me, they are inactive. Not complaining, just wondering.

okay, your roommates are witches.

well, one thing they may be in the healthy BMI range but they might also have a higher percentage of fat and no muscle tone. Maybe long term, when they are older, they may gain weight and be unhealthy down the road.

Maybe they're not eating as much junk food as often as you think. I used to eat like that, but I couldn't eat an entire box of Oreos or an entire bag of chips.

I've wondered the same thing as you for so long!

I asked this question before on CC too, and I never really got an answer I felt worked to describe the people I was thinking of, but anyway, here is the link, and you can check out some of the answers I got:

http://caloriecount.about.com/people-seem-eat -whatever-they-want-ft125346

until i turned 26, i was one of those "eat anything, do nothing and not put on an ounce" types.  i always attributed it to my anxiety keeping me wound tight all the time & my hypoglycemia burning through food like it was going out of style.  even with my metabolism taking the mid-life dive, i need about 300 calories a day more that most calorie calculators say i should. 

Skinny people may APPEAR to eat nothing and do no exercise but unless in very rare circumstances it all boils down to how much you eat. My friend who has a BMI of 17+ exercises about once a week only, skips breakfast in favour of coffee, and would bring a tube of biscuits at school for lunch or just buy a chocolate bar. If you think about it, it's junk food and unhealthy, but it's still a low-calorie diet. And I know for a fact that she eats nearly nothing for days at home, although she eats a whole pizza when out with friends. So most thin people are not miraculously skinny, in fact all the 'skinny' people I know quite well make an effort to work out or naturally make healthy food choices, although they appear to lead sedentary lifestyles.

I was like this, 20 years ago.  I attribute it to appetite regulation - my body knew almost exactly how much fat it had, and suppressed my appetite whenever it got above a certain level.  As a result, my weight (probably) never fluctuated, I don't know because I didn't weigh myself, I didn't even know how much I weighed.

My 18 year old younger brother is kinda like that...he's the classic ectomorph...he's underweight and very small framed...he's so skinny you can see the 6 pack on his 27" stomach...no kidding...he's not even muscular or anything...it's really hard for him to gain weight, but he starts losing pounds when he gets the flu or start moving around for a few days, when it gets real bad he gets almost as skinny as Christian Bale in The Machinist...he eats lotsa junk and has fast food for dinner every single night, infact he's addicted to BK's Whopper and KFC...he doesn't really move much either, is really lazy, and he doesn't even like sports, even though he used to be hyperactive as a kid. It's so weird, I just checked my brother's BMI and it's around 17!! The crazy thing is, while he's underweight and has a super speedy metabolism, his two sisters are obese, and the other one (me) is a struggling average girl, with a very average metabolism....weird....

Hi...I'm 5'6", ~120 & I rarely exercise.

For me, it pretty much 100% comes down to calories. I burn about 1600/ day & eat about 1200-1400 per day, plus maybe a little more on weekends. That's how I maintain the same weight without exercise.

That being said, I need to exercise....I'm in my early 20s, so I have been fortunate so far, but I do not want to grow old with unhealthy organs and stay skinny fat forever!

Hope that helps

My husband is a STICK and appears to eat what he wants whenever. But he doesnt actually eat huge quantities and he walks around for like 10 hours a day. I guess its not magic after all...

Hey there Jon!

Your question reminds me of this episode of Penn and Teller's "Bullsh*t" on the subject of obesity. They conduct an experiment with a skinny guy and a bunch of overweight guys to see who could overcome all these athletic obstacles, arguing that thinness and BMI does not necessarily equal health or athletic prowess. Some people are just born skinny. OOOH! IT'S ON YOUTUBE! WARNING: Lots of cursing! =P 

  Part 1

Part 2

  Part 3

One of the best episodes ever. lol

BMR/RMR is based on population statistics for age/weight/sex, and generally calculated with the Harris Benedict equation.  You'll have individuals far away from the average - probably on the order of 20% either way.  If you took one of your skinny junk food eaters and ran an individual BMR test on him, I'd expect you'd see a high outlier compared to the average population.  A special lucky person.

I used to think I had a low BMR.  But after counting calories for 2 years, I've found that my BMR is almost exactly average.  Nothing special here.

I see... im going to get a B.I.A. (Body Impedance Analysis) test today, those are considered pretty accurate right? I am 5'11, 199 lbs. My BMI is 27.8, but we all know BMI's are pretty much worthless... how can I determine what % of my body should be fat in order to be considered lean, or at a healthy weight so that when I come back from the nutritionist, I can see the % of body fat that I need to lose, and compare myself to the average?

I read a book a long time ago that talked about skinny people not gaining weight.  If certain body types are eating more than they burn, what happens is they start replacing muscle with fat inside their bodies where you don't see it.  Then fat accumulates around their organs, but not under their skin.  Then when they get enough fat inside, they will start to get a bigger belly and may finally start getting some fat under their skin.  Some people just have that pattern of fat accumulation.  And actually they are much less healthy for it than those of us who get the subcutaneous fat first!

Body fat percentage is a much better measure of your overall health and fitness than BMI.  I think for men 20% is healthy and in the teens is desirable.  If you are a bodybuilder you want to be below 10% but that is hard to maintain. 

First off Heavier people have a lower BMR (BASAL METABOLIC RATE "the amount of calories you burn during one day w/No Activity), that's why they gain weight.  Your BMR depends on you LEAN BODY MASS and has nothing todo with being heavier.  Now that said you can actually burn more calories than a skinnier person doing daily activities because you are carrying around a lot of weight, that's like a skinny person carrying dumbbells or a weighted vest all day.  A health Body Fat % for a male is actually 10-18% or somewhere in that range.  for women its a little different, somwhere between 16-24% Is healthy.