Obesity and Genetics

[Edisonian]

We are bombarded with info about how the American people are getting fatter. Obesity is said to be an epidemic. I know that this is because of lifestyle choices in many respects. What I wonder, however, is whether continued obesity passed on through the next few generations will have an overall effect on the human gene pool. What will this mean for distant generations?

[Bluenoise]

I'd assume through the generations it would either select for more naturally skinny people, or for poeple who can handle obiesity better.

[[Tycho?]]

Genes can't play such a large role in obesity, since where the hell did these genes come from to now affect such a large portion of the population?

 

Its mostly diet and lack of excersise.

[Mokele]

IMHO, there are genetic properties that effect it, but they are not the only cause or an excuse.

 

The biggest genetic influence is metabolism. Those with naturally high metabolisms have almost no chance of getting fat no matter what they eat. Those with low metabolisms have more trouble. There's also genetic influences on how fat is stored and where. There are even studies indicating that there may be genetic factors that determine just how much good exercise does for an individual (10 miles on the treadmill might do a lot more for some than others).

 

However, a lot of it is just diet and exercise. And willpower.

 

Mokele

[Bluenoise]

This presents some interesting data. Mostly slanted towards the genetics viewpoint though.

 

http://www.hhmi.org/biointeractive/obesity/lectures.html

[Dr_666]

Hey guys!

 

Obesity, as any other trait that you may think of, has a genetic and an environmental component. If you are interested in the genetic component, have a look at the OMIM (On-line Mendelian Inheritance in Man) database:

 

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=OMIM&cmd=search&term=obesity

 

However, I don't know why it seems to me that you have a misunderstanding about the mechanisms of heredity of evolution. Let me clarify this. People may become fat because of an unhealthy diet but... this will never be transmitted to their children, because acquired characteristics are not heritable!!! So obesity due to environmental causes can never be "passed on through generations" or "affect the gene pool" in any way.

 

Dr_666

[Mokele]

People may become fat because of an unhealthy diet but... this will never be transmitted to their children, because acquired characteristics are not heritable!!! So obesity due to environmental causes can never be "passed on through generations" or "affect the gene pool" in any way.

 

Actually, it *can*, but not in the way you're thinking. Simply put, obesity is caused by a change in our environment, namely the availibility of much more high-calorie, high-fat foods. Because, as you allude to, phenotype is the product of both genes and environment, the change in environment can lead to genes that previously did not produce obesity doing so. For instance, if you have genes that lead to a low metabolism, that would be fine 100,000 years ago, but today, with the current food situation in the US, those genes *do* now cause obesity (in a way).

 

That aside, though, the assertion that it will not affect the gene pool in any way is ludicrous. At the very least, selective pressures have been altered. People with natural resistances or suceptibilities to obesity-related diseases that mere previously rare will have their genes amplified or diminished much more rapidly through the generations on account of this higher selective pressure. And let's not forget sexual selection, including mate choice, which can have a dramatic impact on a species' evolution.

 

Environmental effects, and the effect of environment on gene expression, can and do have a great influence on a gene pool, especially when selective pressure is applied.

 

Mokele

[Dr_666]

...the change in environment can lead to genes that previously did not produce obesity doing so. For instance' date=' if you have genes that lead to a low metabolism, that would be fine 100,000 years ago, but today, with the current food situation in the US, those genes *do* now cause obesity (in a way).

[/quote']

 

I thought that Edisonian had a misconception of the mechanism of heredity and tried to make the point clear.

 

What causes the obesity (in your example) is the interaction of the genes with a certain environment. No changes in the genes are involved. No obesity is being transmitted or "passed on". Only the unhealthy diet is "passed on".

 

You may think that what I said is ludicrous (let's laugh together), but you are talking about something different. I said "obesity due to ENVIRONMENTAL causes can never be passed on through generations..." Aren't you talking about GENETIC causes??

 

People should blame less their genes for their problems and start eating using the brain. I had never seen people as fat as in this country before I came here to do research on genetics.

 

Dr_666

[Mokele]

What causes the obesity (in your example) is the interaction of the genes with a certain environment. No changes in the genes are involved. No obesity is being transmitted or "passed on". Only the unhealthy diet is "passed on".

 

You missed my point. Once the environment has changed, the effects of the genes can change. Even though the gene didn't cause obesity *before*, now it does. Change the environment, and you can change what the gene does. The gene itself hasn't changed, you're right. But the *phenotype* caused by that gene *has* changed, due to environmental alterations to the expression of the gene.

 

So, if the gene *now* causes an obese phenotype, then yes, it *can* be passed on, if the environment remains the same. But that same environment might not cause obesity in all individuals, only ones with certain genes.

 

You may think that what I said is ludicrous (let's laugh together), but you are talking about something different. I said "obesity due to ENVIRONMENTAL causes can never be passed on through generations..." Aren't you talking about GENETIC causes??

 

What I called ludicrous was your assertion that "obesity due to environmental causes can never be 'passed on through generations' or 'affect the gene pool' in any way." As I've *clearly* pointed out, the expression of genes and the resulting phenotype *can* (and often *does*) depend on environmental stimuli. Since phenotype is what natural selection acts on, it's fairly obvious that an environmental change which alters the phenotype produced by genes can alter the selective pressure a gene is exposed to, resulting in alterations in gene frequency.

 

What I am talking about is how genes and environment *interact* to produce a phenotype, and how alterations to the phenotype due to alterations in the environment can affect the selective forces acting on the underlying gene.

 

Mokele

[Dr_666]

It seems to me that I'm not the only one missing points

[Bio-Hazard]

Genetics are passed on no doubt. I assume it's the metabolic rate configuration. The reason most Americans are obese is become they don't weight lift or else actually use something like Atkin's.

 

I think Atkin's was conspired against because of it's great effectiveness. I've lost 180+ lbs on it.

 

It works, I've done it. Lots of people never read the book so they don't know what they are doing.

[Mokele]

It seems to me that I'm not the only one missing points

 

Seems like you're wrong pretty often, including about this. Perhaps you should try actually thinking and reading posts for content. It helps.

 

I think Atkin's was conspired against because of it's great effectiveness. I've lost 180+ lbs on it.

 

It works, I've done it. Lots of people never read the book so they don't know what they are doing.

 

It works, yes, but the question is "does it still work when you come off it, or do you put all the weight right back on?' (which has been the experience of friends of mine), not to mention it's usefulness as a long-term diet.

 

Personally, I'm of the relatively simplistic school of thought "if calories in < calories out, wieght loss, manipulate either as desired to achieve outcome."

 

Either that or Dr. Mokele's Scientificly Proven All Natural Wieght Loss Pill*

 

Mokele

 

* - Contains tapeworm eggs. But they're all-natural.

[Dr_666]

Seems like you're wrong pretty often' date=' including about this. Perhaps you should try actually thinking and reading posts for content. It helps.

[/quote']

 

Really? and how is it that the Owner Of The Truth wastes time with me?

[Sayonara]

We are bombarded with info about how the American people are getting fatter. Obesity is said to be an epidemic.

I disagree. PIES and CAKES are the epidemic; obesity is a symptom of it.

 

Not quite what you were after, I know, but I feel it's an important point.

[Dr_666]

PIES and CAKES are the epidemic; obesity is a symptom of it.

 

Completely agree with you.

[rakuenso]

pfft if we lived in the middle ages we wouldn't be having this discussion, as back then men liked their women plump

[coquina]

pfft if we lived in the middle ages we wouldn't be having this discussion, as back then men liked their women plump

 

I recall that people of Northern European and Arctic heritage tend to put on extra layers of fat for insulation against cold winters. You can really notice it in the faces of Innuit people.

 

Thousands of years ago, before central heating, this is a trait which would have been selected for. Also, people with lower metabolisms would have had an advantage because it would help them endure a long winter when little food was available.

 

I have that heritage, and I have been obese most of my life. I'm 5'4" and I can maintain 161 by walking 3 or 4 miles a day and keeping calories under 1200.

 

Yes - calorie count is what's important. When you try to reduce them, you need to eliminate foods that are high in calories, and low in volume and nutritional content. That means eliminating (or very strictly reducing) both high fat and high sugar or starch foods. Sugars and starch are double trouble because they not only are high in calories, but they stimulate your pancreas to overproduce insulin, which keeps you hungry and craving sweets all the time.

 

I lost weight by eating mostly seafood - such as steamed or grilled shrimp, scallops and fish, some chicken, a little pork, and red meat on rare occasions.

I eat oatmeal for breakfast, low fat cottage cheese, and a lot of fresh fruits and vegetables. I cut out bread, pasta, white rice, pies, and cakes.

 

In August 2002, I weighed 270 pounds, It took me a year to lose 110 pounds by exercising and changing my eating habits. I have kept it off for almost 2 years and do not expect to ever gain it back. I am not on a diet, I changed my lifestyle.

 

My body is very good at conserving calories. This would be a major advantage in a time of famine, but it is a major disadvantage in times of plenty. However, it is not a genetic trait that is likely to be eliminated by natural selection, because people generally don't die of heart disease or diabetes before they are old enough to reproduce.

[soulestada]

Medication can also play a role in obesity as well, like steroids for asthma, and especially anitpsychotic drugs. Zyprexa in particular is notorious for weight gain. Some people have gained a pound a day whlie on it!

[Aardvark]

However, it is not a genetic trait that is likely to be eliminated by natural selection, because people generally don't die of heart disease or diabetes before they are old enough to reproduce.

 

It is true that obesity won't generally kill before the individual is old enough to have reproduced, but obesity may affect the individuals chances of attracting a mate. This could act as a selective pressure upon the genetic traits associated with obesity.

[Evangelante]

In August 2002, I weighed 270 pounds, It took me a year to lose 110 pounds by exercising and changing my eating habits. I have kept it off for almost 2 years and do not expect to ever gain it back. I am not on a diet, I changed my lifestyle.

 

pFFHT.

I went on Atkins and sat around all day.

I use to weigh 340, now i'm 200.

[rakuenso]

<-- 135 6'0 have always been in the lowest 25% of weight for my height, eats whatever the hell I want, does track.

[coquina]

pFFHT.

I went on Atkins and sat around all day.

I use to weigh 340' date=' now i'm 200.[/quote']

 

"pFFHT"? Dunno that one.

 

I doubt you could exercise much at 340 - I couldn't when I was 270 either.

 

How old are you? I am 56. My husband died of heart disease at the age I am now because he refused to take care of himself. He ate high fat foods and wouldn't exercise. He weighed over 350 once - he couldn't weigh himself on a conventional scale - had to weigh on the packaging scales. Diabetes took the weight off him, he didn't have to exercise either.

 

I believe he thought he'd have a warning and then get his act together - it didn't work out that way. I woke up and he was dead.

 

His not waking up was a wake-up call to me to become as healthy as possible. I refuse to dig my grave with my teeth.

[Aardvark]

Coquina, presumably your husband was aware of what he was doing to himself. He could see it on his own body and messages about healthy lifestyles are ubquitous. As such how was it that he could become so over weight and refuse to take action? What is the mental process there, is it denial? Did he perhaps think that he was so over weight that nothing could be done or did he make a conscious decision to enjoy fattening foods and a sedentary lifestyle at the expense of his health?

 

When you decided to get into shape did you get any specialist advice? Was it difficult, someone once called overeating an addiction as difficult to break as a cocaine addiction so i imagine you must have a fair dose of will power. What sort of support did you receive from people and was it helpful?

[coquina]

Coquina' date=' presumably your husband was aware of what he was doing to himself. He could see it on his own body and messages about healthy lifestyles are ubquitous. As such how was it that he could become so over weight and refuse to take action? What is the mental process there, is it denial? Did he perhaps think that he was so over weight that nothing could be done or did he make a conscious decision to enjoy fattening foods and a sedentary lifestyle at the expense of his health?

 

When you decided to get into shape did you get any specialist advice? Was it difficult, someone once called overeating an addiction as difficult to break as a cocaine addiction so i imagine you must have a fair dose of will power. What sort of support did you receive from people and was it helpful?[/quote']

 

Aardvark - he loved food. Especially steak. He wanted me to fix steak every night. He wanted bread and potatoes with lots of butter along with it. He hated vegetables, the only ones he would eat were green beans, lima beans, and corn. I did eventually get him to eat brocolli, but only if I smothered it in cheese sauce.

 

His father died at 60, his mother's brother died at 59 - both of heart disease. They had modified their diets and given up alchohol, but they died anyway. Butch always said he was doomed, because he had the bad genes from both sides of the family. He said he was going to eat what he wanted and do what he wanted, and if it killed him, too bad.

 

There were many aspects to my weight loss - I started seeing an endocrinologist, who did find a problem with my thyroid. I had always eaten what I fixed for Butch, just because I didn't want to prepare two meals. I was so damn sick of steak I didn't touch a piece of red meat for 2 years.

 

When he died, I lost my appetite for the first time in my life. It was a jump start. I do like food - I've challanged myself to figure out ways to prepare tasty meals that are also healthy.

 

I didn't get off scott free by being fat all those years. I have a lot of arthritis in my joints from carrying around all that excess weight, and it's getting worse. When I see young people who are very heavy, I see me when I was younger, and think how much better off I'd changed my lifestyle when I was 30, rather than when I was 53.

 

Being heavy is very discouraging - especially if one is prone to being overweight. I would suggest to anyone who seriously wants to lose weight to get a physical by an endocrinologist. Mine found a problem my GP hadn't found for years. It was making me carry a lot of excess fluid, which made it doubly hard to get off the couch and get moving.

 

Enough soap boxing - sorry...

[michael]

There is a meme about which goes:-

"You are fat because you eat too much and don't exercise-You slob"

 

Unfortunately this is not the case with the epidemic we are now facing.

It may not even be part of the problem!?

 

The in-utero environment is being shown to be a major contributor to later developmental obesity.

Whether the fetus was given not enough, or too much, nutrition in utero is a very major factor in development of later obesity.

 

There are a great many factors that influence obesity unfortunately our society is blinded to them by the above meme.

 

For a sane discussion of obesity issues see

http://www.nytimes.com/2006/08/13/magazine/13obesity.html?ei=5087&en=091c29f788379524&ex=1171771200&adxnnl=1&excamp=mkt_at4&adxnnlx=1164541958-YTbF4XxJ2If9smKoOySdoA