Have you heard the news? The Center for Disease Control's epidemiologists, led by Katherine M. Flegal, Ph.D., published a study in last week's Journal of the American Medical Association that trounces earlier reports claiming "obesity" is killing hundreds of thousands of people a year.
Not only were previous claims of deaths related to "obesity" apparently obscenely inflated, but Flegal et al's more scientifically sound study indicates being "overweight" is actually (gasp!) healthy...and extreme thinness is associated with a greater risk than any of the "obesity" doom-sayers have trumpeted.
Flegal et al. even point out that the studies from which they (and those who hyped the alleged health risks of "obesity") drew their conclusions are correlational in nature, which (as every researcher should have learned in basic statistics and experimental design) means cause and effect can't be assumed anyway.
For more on the Flegal et al. study, here's a note written by University of California (Davis) nutritionist Linda Bacon, Ph.D. in response to questions colleagues were asking about the new study. Dr. Bacon gave permission for her response to be posted here. (I have bolded some sections of her writing for emphasis.)
You asked my response to the Flegal article, and here it is. Feel free
to pass it on to any colleagues. I would like to see these issues being
discussed in more forums. Please let them know that they are welcome to
contact me if they want scientific references to support this or if they
want to learn more.
I think there's important stuff to be learned from it, but I anticipate
that as usual, it will be glossed over by people on the anti-obesity
campaign and quickly dismissed. My concern is that everyone is holding
on to assumptions so strongly -- we are so convinced that obesity is a
terrible problem -- that we don't pay attention when evidence is
presented that shows otherwise. And of course this belief about the
dangers of obesity is so convenient to our message that there's little
incentive to question it. What if we really listened to the data?
A few highlights that stood out for me:
1) Being "overweight" may convey longevity advantages over the low
weights we call "normal" and desirable. Not surprising -- this is
completely consistent with many other studies that show the healthiest
weight to be in the "overweight" range. The ranges defining normal,
overweight and obesity are certainly not data-based.
2) I'm sure some people are going to cling to the 110,000 deaths from
obesity stats, and just shift their argument to targeting obesity as
opposed to just the overweight. But this study won't even support that
argument - most of the 110,000 deaths were attributable to the extremes
of obesity, not where most "obese" people are -- there was only a mild
risk associated with BMI's in the <40 range. And if it's the extreme
you want to pay attention to, I would hope you would pay equally close
to attention to what the study revealed about underweight, because the
risks associated with underweight were far greater than those associated
with all but the highest levels of obesity. There's more support for a
war against thinness than obesity.
Actually, it's remarkable that this study even showed 110,000 deaths,
given that they didn't control for many factors that are associated with
body weight, such as physical activity or nutrient intake -- which could
easily be responsible for some or all of the associations of weight with
mortality.
This is yet another study demonstrating that adiposity itself is not a
big deal (or at least that its risks are highly exaggerated), and the
war on obesity is misguided.
Why is this so important? Well, let's face some other facts:
First, we don't have a clue how to help people lose weight. Sure
there's the old energy balance equation which tells us that if people
just drop their calories or exercise a bit more it should happen. But
what's the reality? It's not happening. Any way you look at it, our
advice isn't panning out. For example, if you look at it from the
perspective of long-term maintenance of weight loss, the data is clear:
weight regain happens over time for the vast majority of people --
whether they try calorie restriction, increased exercise, or both. And
when you look at the physiological mechanism, this shouldn't be too
surprising -- we can see all the biochemical changes when people try to
manipulate their weight, and the compensatory reaction that drives
weight regain. For example, we can see the reduced leptin production
that occurs during dieting, which provokes decreased metabolism and
increased appetite. There's more going on here than the usual gluttony
or laziness argument.
Sure the energy balance equation is a fact of life, but we need to face
the fact that we can't control it to the degree that we believe we can.
Weight gain might be easy, but the body meticulously guards its fat
stores once they accumulate.
But I don't think there's any reason to despair. There's ample evidence
to show that many of the more prevalent weight-related health problems,
such as high blood pressure, elevated cholesterol and triglyceride
levels, insulin resistance, and glucose intolerance, can be improved
through lifestyle changes, independently of weight loss. So that's where
we should put our energy. If people make lifestyle changes, perhaps
they'll lose weight as a side effect. But maybe they won't and we need
to be open to that. Too many times people start to make lifestyle
changes, and then give up when they don't get the weight effects they
want.
Repeated admonitions that we are too fat and need to lose weight,
especially when failed attempts at weight loss has such negative
ramifications (eating disorders, weight cycling and associated increased
cardiovascular disease risk, etc.), has taken its toll. Whether we are
fat, believe that we are fat, fear becoming fat, few people are at peace
with their bodies.
Telling people they're fat and there's something wrong with it will
never be a successful motivator for change, anyway. (If the belief that
being fat and ugly were a successful motivator, I guarantee we wouldn't
have many obese people in this country.) On the other hand, change
happens when people start from a place of self-acceptance -- then they
want a better life for themselves and they're empowered to move on.
This war we're waging on obesity (which we're clearly losing) has caused
much more harm than good. It's time to stop fighting. There's a peace
movement happening. It's called the "Health at Every Size" movement.
It's premise is simple: support people in feeling good about the body
they live in. Encourage them in healthy lifestyle habits that support
their amazing bodies. Thin people (who also are subject to diabetes,
heart disease, etc.) will benefit, as will "fat" people.
Linda Bacon, PhD
Associate Nutritionist
University of California, Davis
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