Genetics of weight loss

Camy · #1 (**permalink**) May 21st, 2008, 02:54 AM

A friend posted this on a different website a few days ago, it is from a NY magazine from last year apparently:

Quote:

The implications were clear. There is a reason that fat people cannot stay thin after they diet and that thin people cannot stay fat when they force themselves to gain weight. The body’s metabolism speeds up or slows down to keep weight within a narrow range. Gain weight and the metabolism can as much as double; lose weight and it can slow to half its original speed.

The scientists summarized it in their paper: “The two major findings of this study were that there was a clear relation between the body-mass index of biologic parents and the weight class of adoptees, suggesting that genetic influences are important determinants of body fatness; and that there was no relation between the body-mass index of adoptive parents and the weight class of adoptees, suggesting that childhood family environment alone has little or no effect.”

In other words, being fat was an inherited condition.

Dr. Stunkard also pointed out the implications: “Current efforts to prevent obesity are directed toward all children (and their parents) almost indiscriminately. Yet if family environment alone has no role in obesity, efforts now directed toward persons with little genetic risk of the disorder could be refocused on the smaller number who are more vulnerable. Such persons can already be identified with some assurance: 80 percent of the offspring of two obese parents become obese, as compared with no more than 14 percent of the offspring of two parents of normal weight.”

A few years later, in 1990, Dr. Stunkard published another study in The New England Journal of Medicine, using another classic method of geneticists: investigating twins. This time, he used the Swedish Twin Registry, studying its 93 pairs of identical twins who were reared apart, 154 pairs of identical twins who were reared together, 218 pairs of fraternal twins who were reared apart, and 208 pairs of fraternal twins who were reared together.

The identical twins had nearly identical body mass indexes, whether they had been reared apart or together. There was more variation in the body mass indexes of the fraternal twins, who, like any siblings, share some, but not all, genes.

The researchers concluded that 70 percent of the variation in peoples’ weights may be accounted for by inheritance, a figure that means that weight is more strongly inherited than nearly any other condition, including mental illness, breast cancer or heart disease.

The results did not mean that people are completely helpless to control their weight, Dr. Stunkard said. But, he said, it did mean that those who tend to be fat will have to constantly battle their genetic inheritance if they want to reach and maintain a significantly lower weight.

The findings also provided evidence for a phenomenon that scientists like Dr. Hirsch and Dr. Leibel were certain was true — each person has a comfortable weight range to which the body gravitates. The range might span 10 or 20 pounds: someone might be able to weigh 120 to 140 pounds without too much effort. Going much above or much below the natural weight range is difficult, however; the body resists by increasing or decreasing the appetite and changing the metabolism to push the weight back to the range it seeks.

The message is so at odds with the popular conception of weight loss — the mantra that all a person has to do is eat less and exercise more — that Dr. Jeffrey Friedman, an obesity researcher at the Rockefeller University, tried to come up with an analogy that would convey what science has found about the powerful biological controls over body weight.

He published it in the journal Science in 2003 and still cites it:

“Those who doubt the power of basic drives, however, might note that although one can hold one’s breath, this conscious act is soon overcome by the compulsion to breathe,” Dr. Friedman wrote. “The feeling of hunger is intense and, if not as potent as the drive to breathe, is probably no less powerful than the drive to drink when one is thirsty. This is the feeling the obese must resist after they have lost a significant amount of weight.”

Here is the URL: http://www.nytimes.com/2007/05/08/he...16&oref=slogin

What do you think?
Camy

P/s: I apologize if this had been discussed already.

nasus · #2 (**permalink**) May 21st, 2008, 04:53 AM

Well, kind of depressing in a way that it seems some of us are "destined" to be fat, but after thinking about it for a minute, I still think it's something you can overcome. Yeah, it will feel like you're struggling against your body. But once you get there, as long as you keep vigilant about it and still want to stay there, it's possible. That's what I'm going to keep telling myself

allyphoe · #3 (**permalink**) May 21st, 2008, 06:34 AM

I think some people do have a genetic predisposition to obesity. My aunt, for instance, and my sister, have the same heavy build, and have never been successful losing much weight, even with long-term good diet and exercise.

I don't think that I have inherited that same predisposition, despite the fact that I've been 70+ pounds heavier than I am right now not just once, but twice. Lack of genetic predisposition makes it easy for me to lose. And the gaining is all mental, not physical.

ChristyP · #4 (**permalink**) May 21st, 2008, 02:43 PM

I don't buy it. I think it's more a person's "relationship" with food. It may seem like it's genetics because family members may have the same mindset when it comes to eating.

maleficent · #5 (**permalink**) May 21st, 2008, 03:27 PM

I think "genetics" ish might come into play because a lot of people get their eating habits from their childhood...

Some people (i'd like tothinki'm one of them because it's an easy excuse) might have a predipostion to gaining weight easily - but unlike what I used to claim years ago -NO, looking at a piece of cheese cake doesn't make me gain 5lbs... It's the eating the c heesecake, and then sitting in front fo the computer for 4 hours that does that...

Camy · #6 (**permalink**) May 22nd, 2008, 11:12 AM

Yeah I also think it is mainly eating habits but the whole separated twins thing goes against that!
I grew up in a skinny family and I got chunky while they all stayed stick thin. May be my illnesses, may be my plain lazyness, may be I was adopted (since they are all dark and I am fair as can be I was always thought that!)... I don't know. But I have always looked like I eat twice as much as my sister while really I eat less than her. But I also move less than her...
Anyhow, I thought it was very interesting to read, and it is definitely something to think about. And I also think just because you have a genetic predicposition doesn't mean you can't try to fight it.
Camy

mjbelkin · #7 (**permalink**) May 24th, 2008, 12:32 AM

Quote:

Originally Posted by maleficent

I think "genetics" ish might come into play because a lot of people get their eating habits from their childhood...

Wouldn't that be nurture and upbringing rather than genetics? Genetics is things like eye colour, etc.

Madrone · #8 (**permalink**) May 24th, 2008, 03:35 PM

I think that if you're going for "thin" as your goal, then there are some people who are never going to be able to maintain that because it isn't their body type. If your natural weight should be 140, but you starve yourself to 125 or 115 because you want to be "thin", it will be tough to maintain. But if your goal is healthy and fit, you'll be able to maintain what works for you. I can't change my body type. Genetically I am what I am and probably I am destined to metabolize calories in a certain way.

However . . .

. . . a lot of this stuff is nurture and the things we learn to eat as children. My mother honestly believes that potato chips are a bonafide side dish. She wouldn't know how to cook a fresh vegetable unless she boiled it to a soggy, squishy death and her idea of healthy eating is to add a side salad with ranch to her steak and french fries. After I hit puberty I was encouraged to hide in my room and read as much as possible and the only atheletic activity I particpated in was marching band. Watching TV on the couch is considered a fine hobby. Both my parents smoke. And drink. And think that olive oil is best confined to a life as a love interest for Popeye.

My mom's sister is horridly overweight, but I imagine that's as much to do with family eating habits as it is genetics. Incidentally, my brother is thin, but he eats only rarely because he is often broke and consumes most of his calories in hamburgers, frozen pizza and free alcohol where he bar tends.

It would be hard for me to maintain 125. Without starving myself, I'll never be a size 8, or probably even a 10. So what. I'll be happy with 135 (give or take) and a healthy, active size 12. Way better than the size 22/211 lbs where I currently reside. I could hit my goal if I'd stop drinking a liter of soda a day and eating a bag of chips on my way home from school every afternoon.

I get that from my mother.

punx122 · #9 (**permalink**) July 5th, 2008, 06:14 PM

if you really want to stay a certain way, you'll do anything to make sure that's possible.