What is obesity? - Mia Nacamulli

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Obesity is an escalating global epidemic. It substantially raises the probability of diseases like diabetes, heart disease, stroke, high blood pressure, and cancer. But what is the distinction between being overweight and being obese? And how does a person become obese? Mia Nacamulli explores obesity.

Lesson by Mia Nacamulli, animation by Kozmonot Animation Studio.

The most basic function of bodily fat
is self-storage of food reserves.

In prehistoric times, natural selection
favored genotypes

that could endure harsh conditions
by stocking the most fat.

With chronic malnutrition being
the norm for most of human history,

genetics evolved to favor fat storage.

So when did body fat become problematic?

The negative impacts of being overweight
were not even noted in medical literature

until as late as the 18th century.

Then, technological advances coupled
with public health measures

resulted in the betterment of the
quantity, quality, and variety of food.

Sustained abundance of good food
enabled a healthier population

to boom economically.

Output increased,
and with it, leisure time

and waistlines.

By the mid 19th century, being excessively
overweight, or obese,

was recognized as a cause of ill health,

and another century later,
declared deadly.

What is the distinction between being
overweight and being obese?

A calculation called the BMI
breaks it down for us.

For example, if someone weighs
65 kilgorams

and is 1.5 meters tall,

they have a BMI of about 29.

Obesity is a condition of excess body fat

that occurs when a person's BMI
is above 30,

just over the overweight range
of 25 to 29.9.

While BMI can be a helpful estimate
of healthy weight,

actual body fat percentage can only
really be determined

by also considering information
like waist circumference

and muscle mass.

Athletes, for instance, have a naturally
higher BMI.

So how does a person become obese?

At its most basic, obesity is caused
by energy imbalance.

If the energy input from calories

is greater than the energy output
from physical activity,

the body stores the extra calories as fat.

In most cases, this imbalance comes
from a combination of circumstances

and choices.

Adults should be getting at least
2.5 hours of exercise each week,

and children a whole hour per day.

But globally, one in four adults
and eight out of ten adolescents

aren't active enough.

Calorie-dense processed foods
and growing portion sizes

coupled with pervasive marketing

lead to passive overeating.

And scarce resources,

and a lack of access to healthy,
affordable foods

creates an even greater risk
in disadvantaged communities.

Yet, our genetic makeup also plays a part.

Studies on families and on separated twins

have shown a clear causal hereditary
relationship to weight gain.

Recent studies have also found
a link between obesity

and variations in the bacteria species
that live in our digestive systems.

No matter the cause, obesity is
an escalating global epidemic.

It substantially raises the probability
of diseases,

like diabetes,

heart disease,

stroke,

high blood pressure,

and cancer.

It affects virtually all ages, genders,
and socioeconomic groups

in both developed
and developing countries.

With a 60% rise in child obesity globally
over just two decades,

the problem is too significant to ignore.

Once a person is obese, the climb
to recovery becomes progressively steeper.

Hormonal and metabolic changes reduce
the body's response to overeating.

After losing weight, a formerly overweight
person burns less calories

doing the same exercises

as a person who is naturally
the same weight,

making it much more difficult
to shed the excess fat.

And as people gain weight,

damage to signaling pathways makes it
increasingly difficult

for the brain to measure food intake
and fat storage.

There is, however, some evidence

that well-monitored,
long-term changes in behavior

can lead to improvements
in obesity-related health issues.

And weight loss from sustained
lifestyle changes,

or invasive treatments
like bariatric surgery,

can improve insulin resistance
and decrease inflammation.

What was once an advantage for survival
is now working against us.

As the world's population continues
to slow down and get bigger,

moving and consciously eating our way
towards a healthier weight

is essential to our overall well-being.

And with the epidemic affecting
every country in the world

for different socioeconomic reasons,

obesity cannot be seen
as an isolated issue.

More global measures for prevention

are essential to manage
the weight of the world.