0:00:00.602,0:00:02.322
Three and a half years ago,

0:00:02.322,0:00:05.618
I made one of the best decisions of my life.

0:00:05.618,0:00:07.650
As my New Year's resolution,

0:00:07.650,0:00:11.858
I gave up dieting, stopped worrying about my weight,

0:00:11.858,0:00:14.898
and learned to eat mindfully.

0:00:14.898,0:00:18.827
Now I eat whenever I'm hungry,

0:00:18.827,0:00:21.890
and I've lost 10 pounds.

0:00:21.890,0:00:24.674
This was me at age 13,

0:00:24.674,0:00:26.906
when I started my first diet.

0:00:26.906,0:00:29.690
I look at that picture now, and I think,

0:00:29.690,0:00:31.722
you did not need a diet,

0:00:31.722,0:00:34.330
you needed a fashion consult.

0:00:34.330,0:00:36.922
(Laughter)

0:00:36.922,0:00:39.960
But I thought I needed to lose weight,

0:00:39.960,0:00:41.423
and when I gained it back,

0:00:41.423,0:00:45.320
of course I blamed myself.

0:00:45.320,0:00:47.827
And for the next three decades,

0:00:47.827,0:00:50.674
I was on and off various diets.

0:00:50.674,0:00:52.730
No matter what I tried,

0:00:52.730,0:00:55.700
the weight I'd lost always came back.

0:00:55.700,0:00:59.132
I'm sure many of you know the feeling.

0:00:59.132,0:01:00.632
As a neuroscientist,

0:01:00.632,0:01:03.584
I wondered, why is this so hard?

0:01:03.584,0:01:06.039
Obviously, how much you weigh depends on

0:01:06.039,0:01:08.687
how much you eat and how much energy you burn.

0:01:08.687,0:01:10.703
What most people don't realize

0:01:10.703,0:01:12.624
is that hunger and energy use

0:01:12.624,0:01:14.759
are controlled by the brain,

0:01:14.759,0:01:18.135
mostly without your awareness.

0:01:18.135,0:01:21.695
Your brain does a lot of its work behind the scenes,

0:01:21.695,0:01:23.911
and that is a good thing,

0:01:23.911,0:01:26.039
because your conscious mind

0:01:26.039,0:01:28.095
-- how do we put this politely? --

0:01:28.095,0:01:31.532
it's easily distracted.

0:01:31.532,0:01:34.175
It's good that you don't have to remember to breathe

0:01:34.175,0:01:36.815
when you get caught up in a movie.

0:01:36.815,0:01:38.755
You don't forget how to walk

0:01:38.755,0:01:41.794
because you're thinking about[br]what to have for dinner.

0:01:41.794,0:01:43.639
Your brain also has its own sense

0:01:43.639,0:01:45.527
of what you should weigh,

0:01:45.527,0:01:48.527
no matter what you consciously believe.

0:01:48.527,0:01:50.567
This is called your set point,

0:01:50.567,0:01:52.088
but that's a misleading term,

0:01:52.088,0:01:53.959
because it's actually a range

0:01:53.959,0:01:56.677
of about 10 or 15 pounds.

0:01:56.677,0:01:59.623
You can use lifestyle choices to move your weight

0:01:59.623,0:02:01.783
up and down within that range,

0:02:01.783,0:02:06.045
but it's much, much harder to stay outside of it.

0:02:06.045,0:02:08.023
The hypothalamus, the part of the brain

0:02:08.023,0:02:10.019
that regulates body weight,

0:02:10.019,0:02:12.459
there are more than a dozen chemical signals

0:02:12.459,0:02:15.275
in the brain that tell your body to gain weight,

0:02:15.275,0:02:18.805
more than another dozen that[br]tell your body to lose it,

0:02:18.805,0:02:22.176
and the system works like a thermostat,

0:02:22.176,0:02:24.323
responding to signals from the body

0:02:24.323,0:02:27.931
by adjusting hunger, activity, and metabolism,

0:02:27.931,0:02:31.796
to keep your weight stable as conditions change.

0:02:31.796,0:02:33.883
That's what a thermostat does, right?

0:02:33.883,0:02:37.191
It keeps the temperature in your house the same

0:02:37.191,0:02:40.198
as the weather changes outside.

0:02:40.198,0:02:42.835
Now you can try to change the temperature

0:02:42.835,0:02:46.454
in your house by opening a window in the winter,

0:02:46.454,0:02:50.251
but that's not going to change[br]the setting on the thermostat,

0:02:50.251,0:02:52.419
which will respond by kicking on the furnace

0:02:52.419,0:02:54.979
to warm the place back up.

0:02:54.979,0:02:58.163
Your brain works exactly the same way,

0:02:58.163,0:03:01.275
responding to weight loss by using powerful tools

0:03:01.275,0:03:02.675
to pushing your body back to

0:03:02.675,0:03:06.459
what it considers normal.

0:03:06.459,0:03:08.480
If you lose a lot of weight,

0:03:08.480,0:03:12.867
your brain reacts as if you were starving,

0:03:12.867,0:03:15.483
and whether you started out fat or thin,

0:03:15.483,0:03:18.510
your brain's response is exactly the same.

0:03:18.510,0:03:20.691
We would love to think that your brain could tell

0:03:20.691,0:03:22.126
whether you need to lose weight or not,

0:03:22.126,0:03:24.307
but it can't.

0:03:24.307,0:03:26.708
If you do lose a lot of weight,

0:03:26.708,0:03:29.050
you become hungry,

0:03:29.050,0:03:32.339
and your muscles burn less energy.

0:03:32.339,0:03:34.819
Dr. Rudy Libel of Columbia University

0:03:34.819,0:03:36.697
has found that people who have lost

0:03:36.697,0:03:38.850
10 percent of their body weight

0:03:38.850,0:03:41.904
burn 250 to 400 calories less

0:03:41.904,0:03:44.289
because their metabolism is suppressed.

0:03:44.289,0:03:46.641
That's a lot of food.

0:03:46.641,0:03:48.896
This means that a successful dieter

0:03:48.896,0:03:51.987
must eat this much less forever

0:03:51.987,0:03:53.402
than someone of the same weight

0:03:53.402,0:03:55.721
who has always been thin.

0:03:55.721,0:03:57.388
From an evolutionary perspective,

0:03:57.388,0:03:59.993
your body's resistance to weight loss makes sense.

0:03:59.993,0:04:03.073
When food was scarce, our ancestors' survival

0:04:03.073,0:04:05.592
depended on conserving energy,

0:04:05.592,0:04:07.830
and regaining the weight when food was available

0:04:07.830,0:04:10.907
would have protected them[br]against the next shortage.

0:04:10.907,0:04:13.433
Over the course of human history,

0:04:13.433,0:04:16.481
starvation has been a much bigger problem

0:04:16.481,0:04:18.227
than overeating.

0:04:18.227,0:04:22.458
This may explain a very sad fact:

0:04:22.458,0:04:25.095
set points can go up,

0:04:25.095,0:04:28.073
but they rarely go down.

0:04:28.073,0:04:30.256
Now, if your mother ever mentioned

0:04:30.256,0:04:32.721
that life is not fair,

0:04:32.721,0:04:35.452
this the kind of thing she was talking about.

0:04:35.452,0:04:38.137
(Laughter)

0:04:38.137,0:04:41.706
Successful dieting doesn't lower your set point.

0:04:41.706,0:04:43.374
Even after you've kept the weight off

0:04:43.374,0:04:45.110
for as long as seven years,

0:04:45.110,0:04:48.990
your brain keeps trying to make you gain it back.

0:04:48.990,0:04:52.280
If that weight loss had been due to a long famine,

0:04:52.280,0:04:54.502
that would be a sensible response.

0:04:54.502,0:04:57.198
In our modern world of drive-thru burgers,

0:04:57.198,0:05:00.671
it's not working out so well for many of us.

0:05:00.671,0:05:04.614
That difference between our ancestral past

0:05:04.614,0:05:06.863
and our abundant present

0:05:06.863,0:05:09.198
is the reason that Dr. Yoni Freedhoff

0:05:09.198,0:05:11.086
of the University of Ottawa

0:05:11.086,0:05:13.743
would like to take some of his patients back to a time

0:05:13.743,0:05:16.166
when food was less available,

0:05:16.166,0:05:17.743
and it's also the reason

0:05:17.743,0:05:19.990
that changing the food environment

0:05:19.990,0:05:24.290
is really going to be the most effective solution

0:05:24.290,0:05:26.446
to obesity.

0:05:26.446,0:05:29.430
Sadly, a temporary weight gain

0:05:29.430,0:05:31.568
can become permanent.

0:05:31.568,0:05:34.071
If you stay at a high weight for too long,

0:05:34.071,0:05:36.830
probably a matter of years for most of us,

0:05:36.830,0:05:41.314
your brain may decide that that's the new normal.

0:05:41.314,0:05:45.374
Psychologists classify eaters into two groups,

0:05:45.374,0:05:47.131
those who rely on their hunger

0:05:47.131,0:05:49.392
and those who try to control their eating

0:05:49.392,0:05:54.562
through willpower, like most dieters.

0:05:54.562,0:05:56.917
Now,

0:05:56.917,0:06:02.027
let's call them intuitive eaters and controlled eaters.

0:06:02.027,0:06:04.149
The interesting thing is that intuitive eaters

0:06:04.149,0:06:06.903
are less likely to be overweight,

0:06:06.903,0:06:10.358
and they spend less time thinking about food.

0:06:10.358,0:06:13.973
Controlled eaters are more vulnerable

0:06:13.973,0:06:16.958
to overeating in response to advertising,

0:06:16.958,0:06:20.975
super-sizing, and they all-you-can-eat buffet.

0:06:20.975,0:06:22.597
And a small indulgence,

0:06:22.597,0:06:25.895
like eating one scoop of ice cream,

0:06:25.895,0:06:31.413
is more likely to lead to a food binge

0:06:31.413,0:06:33.417
in controlled eaters.

0:06:33.417,0:06:35.360
Children are especially vulnerable

0:06:35.360,0:06:38.489
to this cycle of dieting and then binging.

0:06:38.489,0:06:40.872
Several long-term studies have shown

0:06:40.872,0:06:45.408
that girls who diet in their early teenage years

0:06:45.408,0:06:48.688
are three times more likely to become overweight

0:06:48.688,0:06:50.409
five years later,

0:06:50.409,0:06:53.104
even if they started at a normal weight,

0:06:53.104,0:06:55.800
and all of these studies found

0:06:55.800,0:06:58.002
that the same factors

0:06:58.002,0:07:01.133
that predicted weight gain

0:07:01.133,0:07:04.578
also predicted the development of eating disorders.

0:07:04.578,0:07:06.067
The other factor, by the way,

0:07:06.067,0:07:07.482
those of you who are parents,

0:07:07.482,0:07:09.699
was being teased by family members

0:07:09.699,0:07:12.178
about their weight.

0:07:12.178,0:07:13.966
So don't do that.

0:07:13.966,0:07:15.766
(Laughter)

0:07:15.766,0:07:18.232
I left almost all my graphs at home,

0:07:18.232,0:07:20.618
but I couldn't resist throwing in just this one,

0:07:20.618,0:07:22.907
because I'm a geek, and that's how I roll.

0:07:22.907,0:07:25.586
(Laughter)

0:07:25.586,0:07:27.858
This is a study that looked at the risk of death

0:07:27.858,0:07:29.754
over a 14-year period

0:07:29.754,0:07:32.210
based on four healthy habits:

0:07:32.210,0:07:34.346
eating enough fruits and vegetables,

0:07:34.346,0:07:36.618
exercise three times a week,

0:07:36.618,0:07:37.978
not smoking,

0:07:37.978,0:07:40.018
and drinking in moderation.

0:07:40.018,0:07:42.008
Let's start by looking at the normal weight

0:07:42.008,0:07:43.682
people in the study.

0:07:43.682,0:07:45.445
The height of the bars is the risk of death,

0:07:45.445,0:07:47.226
and those zero, one, two, three, four numbers

0:07:47.226,0:07:48.949
on the horizontal axis

0:07:48.949,0:07:50.920
are the number of those healthy habits

0:07:50.920,0:07:52.850
that a given person had.

0:07:52.850,0:07:55.546
And as you'd expect, the healthier the lifestyle,

0:07:55.546,0:07:58.658
the less likely people were to die during the study.

0:07:58.658,0:08:00.242
Now let's look at what happens

0:08:00.242,0:08:01.626
in overweight people.

0:08:01.626,0:08:03.790
The ones that had no healthy habits

0:08:03.790,0:08:05.454
had a higher risk of death.

0:08:05.454,0:08:07.264
Adding just one healthy habit

0:08:07.264,0:08:10.849
pulls overweight people back into the normal range.

0:08:10.849,0:08:13.514
For obese people with no healthy habits,

0:08:13.514,0:08:16.178
the risk is very high, seven times higher

0:08:16.178,0:08:18.314
than the healthiest groups in the study.

0:08:18.314,0:08:22.116
But a healthy lifestyle helps obese people too.

0:08:22.116,0:08:24.618
In fact, if you look only at the group

0:08:24.618,0:08:26.938
with all four healthy habits,

0:08:26.938,0:08:29.658
you can see that weight makes very little difference.

0:08:29.658,0:08:31.698
You can take control of your health

0:08:31.698,0:08:33.618
by taking control of your lifestyle,

0:08:33.618,0:08:35.162
even If you can't lose weight

0:08:35.162,0:08:36.928
and keep it off.

0:08:36.928,0:08:40.271
Diets don't have very much reliability.

0:08:40.271,0:08:42.324
Five years after a diet,

0:08:42.324,0:08:45.526
most people have regained the weight.

0:08:45.526,0:08:48.001
Forty percent of them have gained even more.

0:08:48.001,0:08:49.433
If you think about this,

0:08:49.433,0:08:51.257
the typical outcome of dieting

0:08:51.257,0:08:53.838
is that you're more likely to gain weight

0:08:53.838,0:08:56.453
in the long run than to lose it.

0:08:56.453,0:08:58.953
If I've convinced you that dieting

0:08:58.953,0:09:01.289
might be a problem,

0:09:01.289,0:09:03.881
the next question is, what do you do about it?

0:09:03.881,0:09:08.322
And my answer, in a word, is mindfulness.

0:09:08.322,0:09:10.841
I'm not saying you need to learn to meditate

0:09:10.841,0:09:12.649
or take up yoga.

0:09:12.649,0:09:15.493
I'm talking about mindful eating:

0:09:15.493,0:09:18.894
learning to understand your body's signals

0:09:18.894,0:09:21.267
so that you eat when you're hungry

0:09:21.267,0:09:23.793
and stop when you're full,

0:09:23.793,0:09:25.987
because a lot of weight gain boils down

0:09:25.987,0:09:29.001
to eating when you're not hungry.

0:09:29.001,0:09:30.553
How do you do it?

0:09:30.553,0:09:32.232
Give yourself permission to eat

0:09:32.232,0:09:34.468
as much as you want, and then work on figuring out

0:09:34.468,0:09:36.297
what makes your body feel good.

0:09:36.297,0:09:39.796
Sit down to regular meals without distractions.

0:09:39.796,0:09:41.671
Think about how your body feels

0:09:41.671,0:09:43.787
when you start to eat and when you stop,

0:09:43.787,0:09:46.259
and let your hunger decide

0:09:46.259,0:09:47.881
when you should be done.

0:09:47.881,0:09:50.058
It took about a year for me to learn this,

0:09:50.058,0:09:51.996
but it's really been worth it.

0:09:51.996,0:09:54.989
I am so much more relaxed around food

0:09:54.989,0:09:57.866
than I have ever been in my life.

0:09:57.866,0:10:00.386
I often don't think about it.

0:10:00.386,0:10:03.078
I forget we have chocolate in the house.

0:10:03.078,0:10:06.057
It's like aliens have taken over my brain.

0:10:06.057,0:10:08.851
It's just completely different.

0:10:08.851,0:10:10.841
I should say that

0:10:10.841,0:10:14.325
this approach to eating probably[br]won't make you lose weight

0:10:14.325,0:10:17.319
unless you often eat when you're not hungry,

0:10:17.319,0:10:20.249
but doctors don't know of any approach

0:10:20.249,0:10:25.724
that makes significant weight loss in a lot of people,

0:10:25.724,0:10:29.017
and that is why a lot of people are now focusing on

0:10:29.017,0:10:31.129
preventing weight gain

0:10:31.129,0:10:34.321
instead of promoting weight loss.

0:10:34.321,0:10:35.949
Let's face it:

0:10:35.949,0:10:39.960
if diets worked, we'd all be thin already.

0:10:39.960,0:10:41.984
(Laughter)

0:10:41.984,0:10:43.697
Why do we keep doing the same thing

0:10:43.697,0:10:46.519
and expecting different results?

0:10:46.519,0:10:48.402
Diets may seem harmless,

0:10:48.402,0:10:51.935
but they actually do a lot of collateral damage.

0:10:51.935,0:10:54.386
At worst, they ruin lives:

0:10:54.386,0:10:56.732
weight obsession leads to eating disorders,

0:10:56.732,0:10:58.953
especially in young kids.

0:10:58.953,0:11:04.477
In the U.S., we have 80 percent of 10-year old girls

0:11:04.477,0:11:06.300
say they've been on a diet.

0:11:06.300,0:11:08.530
Our daughters have learned to measure their worth

0:11:08.530,0:11:11.679
by the wrong scale.

0:11:11.679,0:11:13.689
Even at its best,

0:11:13.689,0:11:16.371
dieting is a waste of time and energy.

0:11:16.371,0:11:20.027
It takes willpower which you could be using

0:11:20.027,0:11:22.769
to help your kids with their homework

0:11:22.769,0:11:26.877
or to finish that important work project,

0:11:26.877,0:11:30.364
and because willpower is limited,

0:11:30.364,0:11:35.065
any strategy that relies on its consistent application

0:11:35.065,0:11:37.740
is pretty much guaranteed

0:11:37.740,0:11:39.940
to eventually fail you

0:11:39.940,0:11:43.696
when your attention moves on to something else.

0:11:43.696,0:11:47.691
Let me leave you with one last thought.

0:11:47.691,0:11:50.516
What if we told all those dieting girls

0:11:50.516,0:11:53.578
that it's okay to eat when they're hungry?

0:11:53.578,0:11:55.752
What if we taught them to work with their appetite

0:11:55.752,0:11:57.892
instead of fearing it?

0:11:57.892,0:12:01.396
I think most of them would be happier and healthier,

0:12:01.396,0:12:03.411
and as adults,

0:12:03.411,0:12:07.276
many of them would probably be thinner.

0:12:07.276,0:12:09.220
I wish someone had told me that

0:12:09.220,0:12:12.564
back when I was 13.

0:12:12.564,0:12:14.508
Thanks.

0:12:14.508,0:12:22.867
(Applause)