Why Your Body Fights Weight Loss | Katherine Saunders | TED

I'm going to tell you something that's going to surprise you.

It might be upsetting.

And for some of you, it might explain a lot.

And maybe I can convince you that it's liberating.

Your body is evolutionarily conditioned to gain weight,

which means that your body is also evolutionarily conditioned

not to lose weight —

and definitely not to keep weight off.

According to one explanation called “the thrifty gene hypothesis,”

when we were hunter gatherers,

our body's powerful anti-starvation responses helped us survive.

We had to find our food and sometimes we couldn't,

so our bodies stored calories to keep us alive.

The better we stored calories, the better our chance of survival.

So what changed?

Nowadays, if we can afford food,

there's plenty of it, everywhere.

We don't have to hunt.

Even the gathering is easy.

We can order food to be delivered directly to our sofa,

and portions are huge compared to even 20 years ago.

And a lot of food is tasty, but not so great for us.

We're living in what obesity doctors like me

call an obesogenic environment:

limited need for any kind of physical activity,

and easy access to inexpensive,

calorie-rich, nutrient-poor food

or food-like substances.

Our bodies, primed to keep us alive,

have gone into overdrive

to store all these calories from all of that food,

just in case.

And this is one of the reasons why we have an obesity epidemic

in the United States,

where 42 percent of adults have obesity,

and when we take a look at overweight and obesity combined,

that number goes up to 74 percent.

Let's go back to the biology part of the equation because it gets worse.

For example,

a high-fat diet damages nerve cells

in the area of our brain called the hypothalamus,

which is like a thermostat,

regulating how hungry we are

and how we use energy.

When these nerve cells or neurons become inflamed,

feedback signals from our guts, our digestive system,

and our fat cells

can't get through to our brain

to tell us to stop eating when we're full,

and to stop storing calories when we're not at risk of starvation.

It literally becomes harder to tell how full we are after eating,

and how much fat our bodies really need

to keep us alive.

Without an accurate thermostat sensor,

our bodies store more calories as fat,

and we're more prone to what we call food noise

or persistent thoughts of food,

often leading to maladaptive eating behavior.

And this is how weight gain leads to weight gain.

It's a vicious cycle.

And there are other factors that compound the situation.

Some people are even more genetically susceptible to obesity

or develop health complications like sleep apnea,

that can worsen obesity and other health outcomes.

Many people have even less access and ability to afford healthy food,

and medications can be a huge culprit,

with so many common prescriptions

and over-the-counter drugs that are weight-promoting.

And people with obesity are extremely,

extremely likely to experience weight bias, stigma and discrimination,

which can worsen obesity.

And I can go on and on about factors

other than eating too much and exercising too little

that lead to weight gain.

Oh wait, there's one more thing.

When people with obesity try to lose weight,

their bodies freak out and think they're starving.

The hunger hormone, ghrelin, increases

and the fullness hormones decrease.

It's not your imagination.

Every time you diet, your body holds on to calories.

Your metabolic rate slows down

and your bodies behave as if you're starving.

This metabolic adaptation is fantastic

if, say, you find yourself on a deserted island

with nothing but papaya and tree bark to eat.

But if your coworker has a bottomless candy bowl,

it makes life rough.

So have I convinced you

that obesity isn't just a lack of willpower?

We know all of this from tons of medical research

and rigorously designed scientific studies,

but also from the TV show "The Biggest Loser."

If you haven't watched it,

"The Biggest Loser" is a show

where people with obesity compete to lose weight.

What happens in the show, and what we've seen in other studies,

is that the weight comes back eventually for most people.

We know that within two years,

half of the weight is regained,

and within five years, 80 percent can be regained.

This doesn't mean that "The Biggest Loser" winners are losers.

This means that weight loss itself is often a losing battle.

In 2017,

a patient named Barbara walked into my office.

She had given up.

She had a lifetime of struggle with her weight.

I mean, just some awful, awful treatments and experiences.

Barbara's pediatrician started her on stimulant medications

when she was just seven years old,

and by the age of ten her parents had enrolled her in Weight Watchers.

Throughout her life,

Barbara would lose 100 pounds,

regain them and lose 100 pounds again.

And while her weight went up and down,

her shame remained constant.

Barbara ultimately underwent a gastric bypass surgery,

but after the initial weight loss,

the pounds just crept back.

It felt like Barbara's body was conspiring against her

because it was.

And this is when Barbara was referred to me.

Barbara presented completely hopeless

and blaming her lack of willpower.

What else could it be?

I did two things that day

that completely transformed Barbara's life.

One, I told her, "This is not your fault,"

and two,

I gave her hope that I knew exactly what was going on with her body,

and we had the tools to treat her disease effectively.

Barbara had been made to feel her whole life

like her weight was her fault,

when in reality she has a disease.

Obesity is a disease,

and for those who have it,

for their complex set of individual reasons,

it can be extremely, extremely hard to treat.

Does anyone believe it

when a clothing label reads "one size fits all?"

No, no, right?

Especially when it comes to obesity,

of course not, one size fits none.

For some fortunate folks, diet and exercise work.

For others, surgery works.

But for most people with obesity,

effective treatment requires a combination,

a personalized combination,

of more than one treatment approach

delivered by a trained care team.

People with obesity should be treated like individuals with any other disease,

any other complex chronic disease.

An empathetic, reasonable, thoughtful,

trained provider assesses each individual patient one by one,

understands their version of the disease

and comes up with a very personalized,

long-term treatment approach.

Obesity medications have absolutely transformed our field.

When I started practicing obesity medicine,

the most effective medications we had

were associated with five to 10 percent total body weight loss,

which was still a lot.

But now we can help our patients lose even more weight

and more importantly,

much, much more importantly,

keep that weight off long-term.

This new frontier is absolutely astonishing

and transformative to our field and to our patients' lives.

But we don't want to fall into a pharmacologic craze

and think that the only way to treat obesity is with medication.

We have an entire armamentarium of lifestyle interventions,

other medications, and other treatment approaches.

Treatment, in fact, in whatever form it takes,

should be the last step in the process.

The first, and maybe the most critical

is to finally put an end to the stigma

and the shame and the blame

and the judgment surrounding obesity.

Understanding obesity as the complex chronic disease that it is,

is essential to liberate individuals

and to help them actually get the care that they need.

Plus, when we accurately appreciate the reality of obesity,

this will lead to more innovation and to more treatments.

We're not hunter-gatherers anymore.

Well, except we are.

Think about the buffet line.

Think about the "all you can eat" food,

all the "grab and go" food at your grocery store.

Think about the endless snacks in office environments.

Our biology drives our brain, our bodies

and our behavior to act as if we're still gathering

in a feast or famine environment.

Medications are not a quick fix,

nor are they the easy way out.

Medications are a tool

to help our bodies adapt

to our 21st century obesogenic environment.

They help quiet the food noise

so we can make better food choices,

and they give us a fighting chance

to take on this terrible adversary once and for all.

Thank you.

(Applause)