The myth of metabolism

EvgeniZyntx

Suggest the OP look into hyperthyroidism, hypothyroidism, metabolic syndrome, insulin and a variety of other proofs on metabolic variability.

Pubmed is just a click away.

http://www.ncbi.nlm.nih.gov/pubmed?term=basal metabolic variability

TMcSter

Great topic!

abbylg1983

I can't say it's a myth, because I am not qualified to make that statement, having done little to no research on the topic. I do think, however, just based on who I know, that it is greatly exaggerated. It's easy to shrug off a skinny (or reasonably thin) person eating junk food as a genetic lottery winner, but I would say for the most part (of course there are exceptions to every rule) if someone has a better body than me, she probably eats better than I do and exercises more. Of course everyone knows some freak of nature they swear up and down eats 3,000 calories of crap all day while also spending all day watching TV or playing video games. I don't personally, but I've heard enough people say it that they must be out there.

What is more interesting to me than metabolism is where someone stores fat. My good friend for example, is around 5'8, and while I never knew her weight, she was skinny. Two years ago she started gaining weight, and since I met her, has probably put on a good 20 pounds. She is still thin, but no one would call her skinny anymore. Still, she has a completely flat stomach. She just can't gain fat there. My BMI is probably less than hers (and I have more muscle) and I wear a smaller size, yet I still have a stomach pooch and she does not. Lucky *****.

myofibril

I agree that people become much more sedentary when they get older (desk jobs, driving, etc). I don't think it's so much that they eat more. I think it's a lot more that they eat "more than they need". Meaning, they probably eat about the same maybe a little bit more depending on their lifestyle, but people probably don't need to eat as much as they were younger and more, however little, active.

Sitting on your butt and having the same eating habits can pack on weight fast. That's my experience.

Yep, very good point.

Having said that it's not only "average" people this happens to but also top class athletes. If you are into cycling you will know what happened to Eddy Merckx for a while after he stopped racing but kept eating like he still was...I am sure many people would look at him in his prime and if they didn't know him would assume he had a quick metabolism!

mkstirp

There is more to it than just your metabolic rate. There is most likely a lot of variation in efficiencies too. No one's gut absorbs every calorie. Absorption rates can be affected by what you eat (ie fiber), how much surface area of intestines, and enzymes and hormones. Additionally, fat adsorption is a whole separate process. Most of the fat we eat goes right to storage to be used later when the body runs out of available carbs. The body only needs a bit of fat in the mix to create the energy needed.

blair_bear

Interesting post.

First of all, hormones can effect expenditure so I wouldn't go so far as to say that it's a "myth". But I would also add that people tend to use "metabolism" as a big excuse when either justifying their own inability to lean out OR when looking at another person's physique and pinning it on their "super high metabolism".

This^^ I had Oocytes cultivated and frozen a few years ago in the case of my husband and I wanting to find a surrogate at some point. The hormones they inject you with caused a complete 180 in my body, especially my metabolism. Things were instantly different for me and I had to re-learn my caloric intake/output, etc. I don't think it's a "myth" just based on that personal experience.

GaidenJade

Sorry. I have to respectfully disagree. I can give you two examples. My best friend. She is my height, only two years older than I am and she eats candy, cookies and out eats me at every single turn. I have watched her down a dozen of chocolate chip cookies without blinking. And she is stick thin! She never has an issue with weight, she doesn't exercise, she eats like this every day of her life! She has admitted to having a chocolate addiction.

My second example? My sister in law. She has gained a little weight since marrying my brother, because my family is big on eating crap. However she is still tiny.

Genetics plays a HUGE role in how a person gains weight. The Thyroid, regulates the metabolism, so if your thyroid doesn't work as well as the next persons, then you will obviously have a problem losing weight, or will gain more quickly than another.

Goal_Line

Sure on an individual basis SOME people may have metabolism issues.

But I firmly by and large across broad populations thinner people have different behaviors than fat people.

How do you explain the increase in obesity in America over the past generation? Did we all go through a genetic transformation which impaired our metabolism compared to our parents or grandparents? OR Is our lifestyle different?

I vote lifestyle. For all but a few of us, if we change behaviors we'll get different results.

EvgeniZyntx

And it's worth noting that there are other papers which show wider disparities between metabolic rates across matched populations, but even there you're talking +/- 15%.

+15%? That's 60 pizzas a year for me. It certainly would be visible if I was able to eat that.

ModoVincere

And it's worth noting that there are other papers which show wider disparities between metabolic rates across matched populations, but even there you're talking +/- 15%.

+15%? That's 60 pizzas a year for me. It certainly would be visible if I was able to eat that.

That' my thought....15% of 2000 kCals/day would be 300kCals. That's a bit over 1/2 pound a week gain or loss.

A_Shannigans

I can't say it's a myth, because I am not qualified to make that statement, having done little to no research on the topic. I do think, however, just based on who I know, that it is greatly exaggerated. It's easy to shrug off a skinny (or reasonably thin) person eating junk food as a genetic lottery winner, but I would say for the most part (of course there are exceptions to every rule) if someone has a better body than me, she probably eats better than I do and exercises more. Of course everyone knows some freak of nature they swear up and down eats 3,000 calories of crap all day while also spending all day watching TV or playing video games. I don't personally, but I've heard enough people say it that they must be out there.

What is more interesting to me than metabolism is where someone stores fat. My good friend for example, is around 5'8, and while I never knew her weight, she was skinny. Two years ago she started gaining weight, and since I met her, has probably put on a good 20 pounds. She is still thin, but no one would call her skinny anymore. Still, she has a completely flat stomach. She just can't gain fat there. My BMI is probably less than hers (and I have more muscle) and I wear a smaller size, yet I still have a stomach pooch and she does not. Lucky *****.

I would agree that people like me are definitely not the norm and that in most cases physical activity or diet are behind the differences...but not always.

I do not have trouble gaining at in my tummy now that I can gain though.

A_Shannigans

I wonder if he can explain the skinny person who eats more and is not any more active than their not so skinny friend. It happens something causes it.

Differences in metabolic rates do vary amongst individuals but it is not as great as people believe in many instances - about 3% - 8% were the figures given in the article.

I suspect if you got the skinny and not so skinny individual into a metabolic ward you would probably find the skinny friend ate less and /or had a higher level of physical activity. However, physical activity doesn't only mean planned physical exercise like jogging or going to the gym.

It can also be NEAT / SPA as the posts by Sidesteal reference. Some people just can't keep still for the life of them. What does that do? Burn calories. It's an aggregation of small benefits.

The reason most people put on weight as they get older isn't really about "metabolism" as such or even loss of muscle mass (although that does play a small part.)

It's because people generally become more sedentary and eat more as they get older.

I can't say I was not even slightly more active then my heftier friends but I can say the difference in our activity was minimal enough that my calorie intake should have more than made up for it.

I can tell you when I started to put on the weight I was just as active as I had been for the previous 5 years at least. Although when I switched to an office job the weight gain accelerated which was to be expected.

What I'm saying is this paper over simplifies as does the whole metabolism myth theory. It implies that we all will drop or put on weight at near identical levels diet and exercise being equal. No two humans are that much alike. There are so many variables OTHER than diet and exercise I don't see how that can be qualified.

Again perhaps it's not cause by metabolic weight but some people are able to keep weight off more effortlessly than others. Are they common? No but they do exist.

HealthyBodySickMind

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