Diet interview

This interview is about w from US News and World Report:

http://health.usnews.com/usnews/heal...6obesity_2.htm

The Best Diet: Eat Like Our Ancestors
US News and World Report July 16, 2007

By Katherine Hobson

By now, we all know that most of America is fat. But Deirdre Barrett,
a psychologist with Cambridge Health Alliance and a professor at
Harvard Medical School, says the reasons for this-and how to change it-
may come as a surprise. In Waistland, she lays out the science behind
the obesity epidemic and shatters some of the myths that she says are
standing in theway of really shaping up.

What gave you the idea for the book?

I work in a behavioral medical setting, so I'm very interested in what
people need to do in a practical sense. The major impetus was that I
didn't like what any of the other books out there were saying. There's
so much bad advice, even in otherwise solid books.

And one of those pieces of bad advice is that if we just listened to
our bodies, we'd naturally crave healthy food?

It's counter to biology. That myth is so persistent because it sounds
so good-why wouldn't we be wired with instincts to tell us what's good
for us? The problem is that we're wired for a much different
environment-for a hunter/gatherer society. Our instincts aren't going
to guide us unless we're on the savanna, away from fast food.

You say we're wired to crave nutrients that were "essential but rare,"
like fat, salt, and sugar. But those things aren't so rare anymore now
that we grow and store things instead of hunting them down daily.

Our environment has gone astray. Agriculture is as old as 10,000
years, but even that is a fraction of all human evolution. It was a
huge shift to growing things that simply have a lot of calories, in a
few acres, that store well. That shifted us toward simple and even
more refined carbohydrates.

You also say that contrary to popular belief, our societal ideal of
thinness is actually consistent over time-and for a good reason: It's
healthiest.

It's comforting to think that if your body isn't ideal now, it would
have been in an earlier era. But that's not true. All those E-mails
claiming that Miss America has gotten skinnier over the years? It's
not true. It's been remarkably consistent, except for a small dip in
the 1980s. What all but a handful of too thin actresses and models, as
well as female athletes, look like is what you'd see in the current
hunter/gatherer tribe. They're all at the very slim end of the
recommended BMI [body mass index] range. That is what is absolutely
the healthiest, if you're achieving that by eating small servings of
food and getting exercise. You should focus on healthy habits, not on
the absolute weight. That means it's not healthy to achieve thinness
by vomiting up meals or taking speed.

What about some studies showing that skinny folks don't live as long
as those who are a bit chubbier?

When you really dig into that data, they failed to control for certain
things that may specifically cause disease and make people skinny,
like smoking or undiagnosed cancer. When you take that out, the
healthiest body weight is right at the low end of the recommended BMI
range, as long as you're achieving it in a healthy way.

Is BMI the best way to gauge your health?
It's not at all the best measurement, but some of the really best
research studies use BMI as an outcome. Waist/hip ratio, waist/height
ratio, waist measurements-those all correlate rather well with body
fat percentage, which is what you really want to know. But that is
very hard to measure accurately. As far as BMI goes, for most of us,
it will correlate pretty well. If you're at the low end of the normal
BMI range, you're not going to have a frightening amount of body fat.

There's an indirect interaction between having some kind of
psychological problem and overeating. It's absolutely harder to lose
weight if you're depressed or anxious or have post-traumatic stress
syndrome. I don't mean that those conditions won't aggravate the
problem. But it's not the original, basic cause of most overeating.
And, like smoking, you can change the habit before you fix emotional
problems.

You say that eating healthfully is largely a matter of habit.

We get into routines. Brain imaging has shown that if you have no
routine and are trying to change-say you're in the cafeteria line
thinking, "There's the ice cream; do I want to stick to my diet
today?"-the prefrontal cortex, the area of the brain involved with
complex thought, is active. If you're in a real routine, whether it's
a bad one or a good one, the lower basal ganglia-the older part of the
brain that isn't associated with conscious thought-is active. The
upper advanced brain can be thinking about something else. So if you
always order the salad and the bowl of berries, you don't even think
about the banana split.

It takes willpower to change those habits.

People like to say that willpower is either a myth-it doesn't exist-or
that dieting has nothing to do with willpower. All willpower means is
resolutely following through on decisions without getting derailed by
short-term temptations. It's very straightforward. The most generous
interpretation of why willpower gets bad press as a diet technique is
that lots of people have so little of it. But it's a trainable skill.

If most of us could change our bad eating habits through willpower,
why do you also offer up public policy prescriptions, such as banning
trans fats or taxing unhealthy foods?

In the long term, society has to change. There is no one root of the
problem. We've got to change the current food and nonexercise
environment if you're talking about getting the population as a whole
back to fitness. But most people today want to fix their own health
somewhat faster than the rest of the world is changing. So in the
longer term, and on a wider scale, I advocate things ranging from
outlawing certain things-like advertising junk food to kids-to
changing financial incentives so that, say, agricultural subsidies are
shifted to healthier foods.

And if I want to start with myself, what should I eat?

We should try to eat as much like our ancestors as possible, with
those proportions of protein and fiber. When you look at them, all the
standard diets are essentially converging. If you read the last Atkins
book, he talks about eating fish, not a ton of saturated fat. And [low-
fat guru] Dean Ornish says you should be eating whole-grain
carbohydrates, not simple carbs like white bread. Basically, it's fish
and lean meats, lots of fruit and veggies, and lots of fiber. And
exercise is essential.

Are you optimistic we'll change our ways?

The outlook is quite good for an individual who is very committed to
change. In terms of larger society or the world, I'm optimistic in the
long run and pessimistic in the short run. Things will get worse
before they hit a turning point. At some point it will be clear that
our habits are killing us, and that will finally lead to radical
change. I'd just like to see that happen sooner rather than later. We
waited so long on smoking.

Waistland: The Science Behind Our Weight and Fitness Crisis
Norton, 2007, 320 p, 70 b&w illus., hardcover, ISBN: 0393062163