How do carbohydrates impact your health? - Richard J. Wood

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The things we eat and drink on a daily basis can impact our health in big ways. Too many carbohydrates, for instance, can lead to insulin resistance, which is a major contributor to cardiovascular disease and Type 2 Diabetes. But what are carbs, exactly? And what do they do to our bodies? Richard J. Wood explains.

Lesson by Richard J. Wood, animation by Qa'ed Mai.

Which of these has
the least carbohydrates?

This roll of bread?

This bowl of rice?

Or this can of soda?

It's a trick question.

Although they may differ in fats,
vitamins, and other nutritional content,

when it comes to carbs,
they're pretty much the same.

So what exactly does that mean
for your diet?

First of all, carbohydrate is
the nutritional category for sugars

and molecules that your body breaks down
to make sugars.

Carbohydrates can be simple or complex
depending on their structure.

This is a simple sugar,
or monosaccharide.

Glucose, fructose,
and galactose are all simple sugars.

Link two of them together,
and you've got a disaccharide,

lactose, maltose, or sucrose.

Complex carbohydrates,
on the other hand,

have three or more simple sugars
strung together.

Complex carbohydrates with three
to ten linked sugars

are oligosaccharides.

Those with more than ten
are polysaccharides.

During digestion,

your body breaks down those
complex carbohydrates

into their monosaccharide building blocks,

which your cells can use for energy.

So when you eat
any carbohydrate-rich food,

the sugar level in your blood,
normally about a teaspoon, goes up.

But your digestive tract doesn't respond
to all carbohydrates the same.

Consider starch and fiber,

both polysaccharides,

both derived from plants,

both composed of hundreds to thousands
of monosaccharides joined together,

but they're joined together differently,

and that changes the effect
they have on your body.

In starches, which plants mostly store
for energy in roots and seeds,

glucose molecules are joined together
by alpha linkages,

most of which can be easily cleaved
by enzymes in your digestive tract.

But in fiber, the bonds between
monosaccharide molecules are beta bonds,

which your body can't break down.

Fiber can also trap some starches,
preventing them from being cleaved,

resulting in something called
resistant starch.

So foods high in starch,
like crackers and white bread,

are digested easily,

quickly releasing a whole bunch of glucose
into your blood,

exactly what would happen if you drank
something high in glucose, like soda.

These foods have a high glycemic index,

the amount that a particular food
raises the sugar level in your blood.

Soda and white bread have a similar
glycemic index

because they have a similar effect
on your blood sugar.

But when you eat foods high in fiber,
like vegetables, fruits, and whole grains,

those indigestible beta bonds slow
the release of glucose into the blood.

Those foods have a lower glycemic index,

and foods like eggs, cheese, and meats
have the lowest glycemic index.

When sugar moves from the digestive tract
to the blood stream,

your body kicks into action to transfer it
into your tissues

where it can be processed
and used for energy.

Insulin, a hormone
synthesized in the pancreas,

is one of the body's main tools
for sugar management.

When you eat and your blood sugar rises,

insulin is secreted into the blood.

It prompts your muscle and fat cells
to let glucose in

and jump starts the conversion
of sugar to energy.

The degree to which a unit
of insulin lowers the blood sugar

helps us understand something called
insulin sensitivity.

The more a given unit of insulin
lowers blood sugar,

the more sensitive you are to insulin.

If insulin sensitivity goes down,
that's known as insulin resistance.

The pancreas still sends out insulin,

but cells, especially muscle cells,
are less and less responsive to it,

so blood sugar fails to decrease,

and blood insulin continues to rise.

Chronically consuming
a lot of carbohydrates

may lead to insulin resistance,

and many scientists believe
that insulin resistance

leads to a serious condition
called metabolic syndrome.

That involves a constellation of symptoms,

including high blood sugar,

increased waist circumference,

and high blood pressure.

It increases the risk
of developing conditions,

like cardiovascular disease

and type II diabetes.

And its prevalence is rapidly increasing
all over the world.

As much as 32% of the population
in the U.S. has metabolic syndrome.

So let's get back to your diet.

Whether your food tastes sweet or not,
sugar is sugar,

and too many carbs can be a problem.

So maybe you'll want to take a pass

on that pasta sushi roll pita burrito
donut burger sandwich.