WEBVTT

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Which of these has 
the least carbohydrates?

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This roll of bread?

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This bowl of rice?

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Or this can of soda?

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It's a trick question.

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

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

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So what exactly does that mean
for your diet?

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First of all, carbohydrate is 
the nutritional category for sugars

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and molecules that your body breaks down
to make sugars.

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Carbohydrates can be simple or complex
depending on their structure.

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This is a simple sugar,
or monosaccharide.

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Glucose, fructose, 
and galactose are all simple sugars.

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

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lactose, maltose, or sucrose.

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Complex carbohydrates,
on the other hand,

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have three or more simple sugars
strung together.

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Complex carbohydrates with three
to ten linked sugars

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are oligosaccharides.

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Those with more than ten
are polysaccharides.

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During digestion,

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your body breaks down those
complex carbohydrates

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into their monosaccharide building blocks,

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which your cells can use for energy.

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So when you eat 
any carbohydrate-rich food,

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

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

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Consider starch and fiber,

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both polysaccharides,

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both derived from plants,

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both composed of hundreds to thousands
of monosaccharides joined together,

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but they're joined together differently,

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and that changes the effect 
they have on your body.

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

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glucose molecules are joined together
by alpha linkages,

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

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

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which your body can't beak down.

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

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resulting in something called
resistant starch.

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

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are digested easily,

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quickly releasing a whole bunch of glucose
into your blood,

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

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These foods have a high glycemic index,

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

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Soda and white bread have a similar
glycemic index

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because they have a similar effect
on your blood sugar.

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

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

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Those foods have a lower glycemic index,

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

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

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your body kicks into action to transfer it
into your tissues

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where it can be processed 
and used for energy.

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Insulin, a hormone 
synthesized in the pancreas,

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

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When you eat and your blood sugar rises,

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insulin is secreted into the blood.

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It prompts your muscle and fat cells
to let glucose in

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and jump starts the conversion
of sugar to energy.

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

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helps us understand something called
insulin sensitivity.

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The more a given unit of insulin
lowers blood sugar,

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the more sensitive you are to insulin.

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

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The pancreas still sends out insulin,

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

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so blood sugar fails to decrease,

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and blood insulin continues to rise.

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Chronically consuming 
a lot of carbohydrates

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may lead to insulin resistance,

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and many scientists believe
that insulin resistance

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leads to a serious condition
called metabolic syndrome.

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That involves a constellation of symptoms,

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including high blood sugar,

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increased waist circumference,

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and high blood pressure.

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It increases the risk 
of developing conditions,

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like cardiovascular disease

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and type II diabetes.

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And its prevalence is rapidly increasing
all over the world.

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

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So let's get back to your diet.

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

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and too many carbs can be a problem.

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So maybe you'll want to take a pass

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on that pasta sushi roll pita burrito
donut burger sandwich.