What's the Best Recipe for Reducing Obesity?




Uploaded by sphweb on 18.05.2012

Transcript:
Our next speaker is Karen Peterson. Not only is she the director of our new NIEHS Children's Center,
but she's also the leader of our human nutrition program. And I have the pleasure
of knowing Karen for over twenty five years, having worked together at Harvard
for eighteen
Karen Peterson.
Thank you, Howard.
What he means is I'm old, so...
But what that means is he's old too!
The secret to life is to get a lot of physical activity,
some chocolate every day,
and entertain an adolescent's sense of humor. It will get you through a lot.
And I'm hoping it will get me through this next session.
So what I'd like to talk about is, what's the best recipe for reducing obesity?
And what you see here is the cover of my very first cookbook. As a child who grew up
in rural Montana, I was given free rein by my mother, and my father
to cook. And I would come home after school many days and put together ingredients
in unusual ways, little experiments.
And, you know, I was had a great hope of greeting my parents with some new
confection or concoction.
I have to confess that some of these were more palatable than others.
But, they did leave me, really, with a sense of excitement about inventing.
Taking things apart, inventing, putting them back together. And at the minimum,
you're always left with the next best question.
So, I'd like to apply this paradigm of recipe, if you will humor me,
to think about how we think about the development of obesity.
So, what this slide shows is a chart that's probably common to many of you.
What it shows is the changes in the prevalence of children who are
classified as obese from the 1970s, near to the present time.
The purple bars are preschool children, the gold bars are school-age children,
and the [blue bar] children are adolescents.
So, the children we autually care about are those that we're graphing in this figure,
are those that grow at what we'd say is the top of the growth chart. So, this is
simply a growth chart for body mass index. It's the same index that we use
to categorize obesity in adults.
But, we have different cut-offs based on the fact that children grow,
and adults are not supposed to grow. Although, I can verify that that's actually a myth.
One does grow, particularly as one reaches middle age.
The take-home message that I want to highlight from this is that
we have seen, and I think many of you hear in the news on a regular basis, that the
rates of obesity-- the proportion of children who are obese--
has increased dramatically over the past few decades. We were not in really big
trouble in the '70s, nor even in the early '80s.
But, by the 1990s, we saw that we had a doubling of obesity,
the proportion that we'd expect to be over the ninety-fifth percentile,
in preschool children. And we had close to a tripling of obesity by the time we
reach the year 2000, in school age and adolescent children.
What's actually even more concerning is that we've continued to see increases since
the year 2000,
including in our youngest children, or at least children two to five, that are shown
in this slide.
And, this is in a period when we know that the public health community has gone
all out to try to reduce obesity.
And, here's another chart that
illustrates what happens across the age span. These data are the very most recent data
that are representative of the U.S. population, that were published in January.
What they show, a couple things I wanted to highlight here. They also show the
differences by males and females.
This is an epidemic that seems to keep changing face.
So, about ten to fifteen years ago, we had a greater concern about
obesity in females, particularly during adolescence. But, what you can see
from this chart, is actually prevalence of obesity
is three times what we expect in young boys, two times what we expect in girls.
And the prevalence of obesity is highest in males across all age groups.
So, we've forgotten something. We need to get smarter about how we tackling the epidemic.
The other thing I want a highlight is that we have
very important transitions from preschool to school years,
and from adolescence into young adulthood where we see a near doubling in obesity rates.
So again,
this is at the end of a ten year period
where probably, my guess would be, that most public health expenditures,
or a very great proportion,
went to addressing this problem.
Clearly we have fallen short. So, what I want to do today, if you'll humor me,
is to use the metaphor of recipe to step back, and I'm setting the stage for Dr. Maynard)
which is to think about how we think about the problem of obesity.
And perhaps that will be the root of our inability to come up with a
truly effective solution.
So, you know from Dr. Dolinoy's talk, and from the data that I just showed,
that some of the roots of obesity are in childhood. So let's
go back to childhood. What is this?
This is from "The Little Prince."
This was a favor book of mine, I think of Howard's as well, as a child. And I
thought it was a great metaphor for us. Get ready for this.
What's causing the bulge? So, you'll recognize this actually looks like
the distribution of obesity in U.S. right now.
But, as the Little Prince found,
the most obvious and simple explanation-- it's a hat-- actually fell short of
illuminating what were the underlying causes,
which in his world, his reality was
a hungry snake that had swallowed an elephant.
I realize we're really layering up the metaphors, but
this, I also found an elephant metaphor, because we remember the story of of blind men
who have their hands on different parts of the elephant.
But, anyone of them cannot provide an integrated understanding of the complexities
of the condition.
So, what is the current paradigm that we've been using in the past ten years
in the U.S.? A little bit longer to
develope obesity prevention and treatment programs and policies.
It most simply said, and I think you'll see this in many, many articles, said that
obesity is simple.
It's a problem of energy imbalance: too much energy in
not enough energy expended. Too much energy spent sitting,
and that it's influenced
predominately by dietary and physical activity behaviors,
including screen time.
So, an important advance of the last ten years in this paradigm was,
before the year two thousand,
this was the whole puzzle and obesity was
largely considered an acute condition.
But, what we now know is that it's a complex condition, it's a chronic
condition. And an important advance in the model was that there are many, many
influences on individual's lifestyle behaviors.
It turns out,
if you eat a brownie and it's too large
it may not be all your fault. Of course, you might try cutting it down into quarters.
That there are other influences that we need to think about, and these
have been, actually, primarily
the focus of public health efforts.
What are the influences and behavioral settings-- childcare, schools,
work sites, health-care settings--
that might influence your ability to maintain a healthy lifestyle?
In addition, now there's increased emphasis on sectors of influence.
This includes things like the built in environment, food availability and accessibility,
and even the food system.
And, finally, social norms and values. These could include
norms and values that vary across countries
by socioeconomic group and in different race ethnicities.
But, is this paradigm enough, or are we falling short?
So, we decided, in fact, that we did not have the best recipe. We might
not have the best framework.
So, one of our very talented Nutritional Sciences PhD students, Tiffany Yang,
who's in the last row,
was willing to accept the mission of going out onto the web in search of
a better food metaphor that might capture layering,
and allow us to bring in some other biologic influences in a more
nuanced notion of environment.
So, here's what she came up with. And she did say in her email, "this is only a
selection of our favorite images,"
that she had a hard time restraining herself. Which I thought, itself,
was a great metaphor.
She's actually very slim, and she's hiding out near the back of the room,
so I won't point her out.
So, what we found...this is actually, we had a number discussions in the
neighborhood too, about the best way to approach this.
So, one of my neighbors thought that trifle, a very patriotic trifle would
be the best metaphor. Here, we have the optimist seven layer rainbow cake.
This, I think I've dubbed "March Madness Seven Layer Dip."
But, our personal favorite was actually wavy lasagna.
For making Howard pay for asking us to do these talks.
So, why this metaphor? So, I wanted to bring it up as way of thinking about a
more complex layering of influences that would allow us to bring biology, a better
understanding of environment, to our understanding of influences on behavior.
So, we saw this this chart before.
And, I would liken this to the "Little Prince's" hat. That it tells us,
actually, very little. One of the things we can tell though is that
this is probably not where we want to focus. First of all, if all the
interventions were in school age years, what happened here?
Would it have been worse? This looks worse already, to me.
That where we probably need to look for clues is earlier in the preceding periods.
And, in fact, what we'll see in the next slide is that we have several periods
that are sensitive in terms of the development of obesity.
This is just one illustrative chart that
highlights something that Dr. Meeker mentioned, is the importance of
considering life stages.
And that is also true during childhood. So, this graph actually shows that
two children started out with very low infant weight gain. This is the earliest
sensitive period.
The transition from being in the womb to infancy.
And one of those children ended up hugging the bottom of the growth chart,
whereas the other was still lower body mass index in preschool years, but
you can see,
actually ended up overweight by adolescence.
Maybe that's genetic, but I think I would be a little suspicious of that.
Whereas Dr. Dolinoy talked in her work,
tells us a lot about very early influences, including early rapid infant
weight gain on the development of obesity and chronic diseases.
But, you can see from these two examples, that's not the end of the story either.
So, what's the point of this very busy slide?
That when we think about the lifestage framework, and we think about the
development of obesity, we actually have several different sensitive stages
during childhood
that are periods for peak incidents of obesity. But, at the same time, there are also
periods of opportunity. So, this
figure here simply overlays those three sensitive periods for development of
obesity that we know from the literature,
that are lined behind those population trends,
overlays them on a growth chart. And then, if you'll permit me, one more time, we bring
back the lasagna, aka a layered
picture of the influences. This is, itself, very simplistic.
But, the work that we're able to do in the department
lets us do a couple things.
And we're actively engaged on this in our Children's Environmental Health Center,
is to have a more complex understanding of environments.
The nutrition/obesity community will look at social, and to some extent,
physical environment and influences on
health behaviors that lead to energy imbalance and obesity.
But, you can see from Dr. Meeker's talk, that there's a number of chemicals
that also could influence these processes and have influences here.
So, we decided to put behavior in the middle of the spectrum.
And, another aspect of, I think it's really the future, sort of the
next steps we'll take
is, in fact, behaviors may be important in maintaining energy balance.
But, they also have a number of implications for
modifying the toxic effects of exposure, the effects of toxic exposures,
on epigenetic changes,
and even parent and child feeding, and other kinds of interactions in early
life can effect those changes.
So, in closing,
I'll leave you with the lasagna metaphor.
I really sincerely doubt that this is going to be the best paradigm for
understanding the causes
of the development of obesity.
But, in the spirits of the tet talk today,
I hope you'll agree with me it's actually quite fun to go back to your
paradigm, pull it apart, and we would actually be very happy for
some suggestions about how to think about this challenging problem better. Thank you.