Jeff Duntemann's ContraPositive Diary

Yesterday I ran across a nice article in the New York Times, which is an excerpt from Gina Kolata's new book, Rethinking Thin. I'd heard the odd reference to fifty-year-old research from Jules Hirsch, a physician at Rockefeller University, that strongly correlated (70 percent—strong!) obesity with genetic heritage. The article goes into some detail about that research (and much else) and is worth reading, and I may buy the book.

As I've said many times in this space, we know far less about the workings of the human body than we claim to, and the stronger the conventional wisdom about one health condition or another, the less the scientific process seems to hold any authority. Perhaps the strongest conventional wisdom about obesity is that it's all your fault, and if you would just stop being such a glutton or maybe walked around the block once in a while, you'd lose weight.

Like almost everything else in biology, it is hugely more complex than that. Let me recap what I've learned in my 54 years. (My long-time readers have read some of this before.)

Age matters—in some people more than others. The woman who picked up my responsibilities when I left Xerox in 1985 told me that when she was 41 or 42, she "blew up like a balloon." (Her own words.) She didn't change her diet at all, but in the space of a couple of years, she put on over fifty pounds. Nothing bad happened in that time; she didn't get divorced, or lose her job, or a parent, or any other loved one. She was a sweet person who lived simply and sanely, but as she entered middle age she just gained weight quickly and irreversibly. I had lunch with her many times in our last year as co-workers, and she ate almost nothing compared to what I ate.

Diet matters—in some people more than others. I gained twelve pounds very quickly after I got married, simply because I started eating regular meals. As a bachelor I lived on Golden Grahams cereal and not much else; eating alone was boring and I walked all day at work with a toolbag in one hand and a vacuum cleaner in the other. Once I began eating sane meals as Carol's spouse, I gained weight but felt better. I gained a little more weight (about fifteen pounds) in my mid-forties, but I'm pretty sure now that it had less to do with age than with my body's reaction to sugar, particularly the high-fructose corn syrup in all the iced tea and Mountain Dew that I was downing daily in the land of single-digit humidity. (I know, it was all the wrong stuff to drink. I don't make that mistake now.) Once I mostly eliminated sugar from my diet, I lost fifteen pounds in almost no time at all. I think the body handles sugar better when you're young, and a good deal of that may be a matter of insulin resistance. The first thing anyone should do in an attempt to lose weight is knock out sugar. It's not as hard as it sounds and I know numerous people whose reactions were like my own. On the other hand, I have friends who claim that sugar has no effect on their weight, and that what makes them gain weight is fat. I'm suspicious, but I'm also an empiricist. What works, works, and it's our job to do the science and figure out how and why.

Exercise matters, though in subtle ways and maybe less than we think. I didn't gain any weight at all when I went from a vigorous walking job to a desk job in 1977. I began walking regularly in my late thirties, not so much to lose weight but to dissipate job stress and feel better. I didn't lose weight when I began walking. When I get sick and stop walking, I don't gain weight. On the other hand, once I began a weekly weight-training regimen, I put on significant muscle mass. Muscle burns calories 24/7, and since I gained muscle, my weight has drifted downward. Most of the lost weight came out of my gut, which from a health standpoint is the worst place for men to have it.

So. Do genetics matter? Over the years, I've become increasingly convinced that they do, based on observations in my own family and circle of friends, and in articles I've read. I'm convinced that there is a "fat gene" and (more to the point) an inherited weight value that the body likes to maintain if it can. (For me, that value is about 155.) Fat people can get thin if they reduce themselves to a starvation diet (see the Times article referenced earlier) but as soon as they begin eating normally, the weight comes right back on. Further research I've recently found (courtesy Frank Glover) indicates that there is definitely a "fat gene" in mice, and chemicals have been discovered that seem to override the fat gene's regulation of mouse metabolism, which then burns calories more quickly.

Sugar—of which there are several different kinds—is a wild card. I don't think we completely understand how sugar affects human metabolism, and we desperately need more research. Sleep may also be a wild card; a Mayo Clinic seminar we attended once presented some research suggesting that sleep deprivation both raises your blood pressure and increases your weight. I intuit that the "freshman fifteen" effect may happen because college kids studdenly stop getting a full night's sleep. Ditto women with newborns who complain of not losing their pregnancy weight—getting only three good hours of sleep a night may be an issue. We certainly need more good science here.

The conclusion I come to is that weight is, at the bottom of it all, about metabolism. If we turn metabolism up, we lose weight. Genes appear to regulate the body's metabolism within certain bounds, and although we can tweak metabolism by tweaking diet, exercise, and muscle/fat ratios, metabolism dictates whether we are thin or fat, given enough food to not feel ravenous all the time.

But what we really need to do is stop assuming that we know more than we do—and we really really need to stop assuming that fat people are all lazy gluttons.