I, and I believe ddaniels as well, define "genetic weight range" as the nebulous array of genetic traits and factors that affect our body's absolute size and composition (measured as weight). It is the thinnest and the fattest you can become by manipulating your environment to favor the expression of genetic traits that promote thinness or fatness.

I don't think any one is saying normal weight is a matter of genetics, although, some people have an easier time obtaining normal weight for genetic reasons (narrow range).

I think the confusion here is that people think of weight range as restrictions, when ironicaly it's really about possibilities. No one is supposed to be fat. That obesity is a relatively new problem shows that normal weight is entirely possible for most people. Those of us who become obese are not supposed to be fatter... it's just it's easier for us to be that way, providing the environment permits obesity, than it is for people who have a smaller range. Seeing as our default environments are extremely triggering of sensitivity to weight gain, those who have the biggest ranges will "suffer" the most. When it comes to genetics and weight, the difference between thin people and fat people is not where the range is (i.e. 130-200 vs 100-170). The difference between thin people and fat people is that fat people have genetic factors which make the size of the range much larger (i.e. 100-250 vs 100-150).

For whatever reason - sensitivity to high sugar diets, slower metabolism, a hormonal profile favoring building fat over muscle, whatever - our ranges are bigger. Because we have more possible weights we can be, we have to pay much more close attention to our choices since we are so sensitive to environmental changes that affect weight. It's harder, but normal weight is possible for almost all of us if we are careful to err in favor of it.

I hope this has helped clarify what we are talking about when we say "genetic weight".

Another way to look at this genetics issue is using height as an example. The correlation between genetics and height is 1.00, meaning, your height is *almost* totally determined by genetic factors. Sometimes those factors are easy to predict, for example, one would expect 2 tall parents to have a tall child. However, sometimes 2 tall parents can end up with a short child. How did that happen?!! I have no idea, but there was something in the "genes" that wasn't as obviously apparent, or easy to predict.

Even with such a stronge 1.0 correlation correlation between genetics and height, there is still some environmental wiggle room. For example, poor nutrition or intense physical demands placed on a child during critical growth periods can result in stunted growth. This is why you will see some female gymnasts not achieve their full genetically programmed height potential- environment interacted with that genetic programming, and full height was not achieved. In the case of height, however, the correlation 1.0 is so strong, that it needs a pretty big event to over rode the genetic programming.

Where weight is concerned, there is also a significant genetic component, but not quite a strong. The correlation is .85. So, there is more room for all sorts of environmental factors to influence weight, but there is still a significant genetic influence as well.

So, all things being equal if you have two women; same age, same height, same exercise level, etc. who both loose weight and end up at 100lbs., woman "A", with reasonable eating and activity habits, may not have too much trouble maintaining that weight, but woman "B" may have a great deal of trouble maintaining that weight, because her genetic programming has her better suited to maintain a higher weight, like 110lbs. It's not that she is unable to be 100lbs., it's just that she's going to be fighting her genetics to maintain it comfortably- it's not a "natural" weight for her.

Sorry Nora, I'm still feeling stupid. Is there anything in the scientific literature, or quasi-scientific literature where I can read about the .85 correlation and the whole concept of "genetic weight"?

There are lots of things out on the web about weight and genetics, much of the research is obesity related, but some has to do with weight maintenance. However, The particular correlation statistic I quoted came from a clinical conference I was attending this past fall for eating disorder treatment professionals and was part of a lecture by Craig Johnson, M.D. who is an internationally recognized eating disorder researcher and clinician, and has a great deal of credibility in the professional community. He has lots of publications, etc. The strong correlation between weight and genetics is agreed upon by most everyone. It's the details that get debated.

http://www.vivo.colostate.edu/hbook...c/fatgenes.html


I think the "debate" gets hot and politicized when people start talking about obesity, as in, "I can't help it if I am obese because I am genetically programmed to be this way." At that point, the inter-relation between science and politics and public health policy start to get a little confusing! But, whether a person is genetically UNABLE to loose weight is not so much the issue I was commenting on, but instead, how difficult is it for a person to maintain a weight loss that is below their genetically programmed weight range. That difference may only be 10 lbs., but we can sure make ourselves crazy over those 10 lbs. if they are important to us!

I believe that living below that personal range isn't impossible, but it will be harder- maybe MUCH harder, depending on how low we try to stay. I think it's important to remember, when we get to comparing ourselves to each other , as in, "She and are the same height and age and activity level, etc.- why can she eat more *whatever* than I can and she doesn't seem to have any trouble?" that sometimes it is our genetics that is making the difference- perhaps more powerfully than we realize. How hard we want to fight against those genes and how much energy we want to invest in the fight is something each of us have to decide, of course.

Thank you. I have seen some of that research, or the reporting on it at least, but was not sure if we were thinking of the same thing. It seems we are pretty far from being able to identify a genetic weight for any one human individual right now, and, of course actual people are subjected to a whole range of environmental/social influences that are probably pretty important too.

I am not, by any means, discounting what you are saying.

Have you noticed though how many of us are the fat ones in otherwise more slender families? While there are generations of obese individuals in some of our family histories, others of us are definitely the odd man or woman out.

Nora, to maintain your current weight take in 10-12 calories per pound.

If you weigh 115, then 1150 calories to 1380 calories would be maintenance.

No two people have the same carbohydrate threshold. That is tied to your metabolism and degree of physical activity. The reason Atkins had you increase carbs til weight loss stopped was to determine that threshold for you. That was the purpose of premaintenance and maintenance. When you increased carbs too far you would see a gain.

does this help?
Karen