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Carbohydrates Explained

Buzzle Staff
Despite much rhetoric to the contrary, carbohydrates are not poison, magic, or fat-making. But they are quite interesting.
High-carb, low-carb, no-carb... Some people say carbs make you fat, other people say that you need them for fuel. Some people won't touch them with a ten-foot pole, others insist on eating giant bowls of them nightly. So what exactly is a carbohydrate?

Chemically Speaking

At the molecular level, carbohydrates are carbon atoms with water molecules attached to them. This may sound like it would just give you wet carbon, but it doesn't work that way. When you combine things at this level of organization, you end up with a whole new thing.
Look at it this way - hydrogen and oxygen are gases at room temperature, but combine them molecularly in a 2:1 ratio, and you get water, which is a liquid at room temperature.
Carbohydrates come in three major sizes, depending upon how many water molecules are attached to the carbon. The smallest carbs are sugars, the larger ones are starches, and the very largest are fibers. We eat all three forms, and they provide us with different things we need.

Sugars

Sugars are way more than just the sweet stuff you put in your coffee. Sugars can be simple or complex, and they are our bodies' basic unit of fuel. Glucose is a simple sugar, and your body's preferred energy source. In other words, no matter what kind of sugar you eat, your body will break it down into glucose, because that's the sugar it knows how to use.
When you eat carbs, your body extracts a certain amount of glucose right away to keep your energy levels up. That's why you feel refreshed after a meal. Any glucose left over gets converted into glycogen and stored in your muscles and liver for later use.
If the food that you ate contained simple sugars, the glucose generally hits you all at once, then tails off rather quickly. This is why eating candy for lunch will give you a quick sugar rush, then leave you crashing an hour later.
For more sustained energy, you need a larger carbohydrate molecule that is large and complex enough to leave lots of left over glucose. Enter the starch.

Starches

Starches are basically sugars with more water molecules attached. In fact, starchy foods break down into sugars pretty quickly. They're generally found in grains, but vegetables like peas and potatoes are good and starchy too.
To taste the breakdown of starch into sugar in real time, take a bite of white bread and chew it until it is completely liquefied. If you chew it long enough, it will begin to taste sweet, as the glucose molecules become detached from the rest of the carb molecules, thanks to a salivary enzyme called amylase.
Starches are not especially helpful on their own, other than the fact that they deliver a higher dose of glucose in a smaller package. The sugar will lift you up and let you fall just like the simple sugars did, but it may take a little longer because there's more of it.
Endurance athletes rely on starchy foods to fill their muscles with glycogen, that helps them push toward the finish line during long races once the glucose supply is completely drained.
To taste the breakdown of starch into sugar in real time, take a bite of white bread and chew it until it is completely liquefied. If you chew it long enough, it will begin to taste sweet, as the glucose molecules become detached from the rest of the carb molecules, thanks to a salivary enzyme called amylase.
Starches are not especially helpful on their own, other than the fact that they deliver a higher dose of glucose in a smaller package.
The sugar will lift you up and let you fall just like the simple sugars did, but it may take a little longer because there's more of it. Endurance athletes rely on starchy foods to fill their muscles with glycogen, that helps them push toward the finish line during long races once the glucose supply is completely drained.

Fiber

Fiber is the largest of the three carbohydrates, and it is the most beneficial to the body. Because it has the most water molecules attached, it takes a very long time to break down completely. So instead of sending your energy straight up and then straight down, it provides more of a 'slow burn'-type controlled flow of glucose to your bloodstream.
In fact, fiber is so difficult to break down, that humans can't even digest it all the way. The parts we can't process make their way to our intestines, where they basically scrub our plumbing clean and provide bulk to form stools.
Whole grains are good sources of fiber, but fruits and vegetables are even better (but you have to eat the skin for that).
Remember that sugar, starches and fiber don't exist as separate foods for the most part - all plant foods contain all three types of carbs. It's only through processing that we get things like pure sugar (table sugar is sucrose), fiber powder, and cornstarch.

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When choosing the carbohydrates to eat, it is best to go with the most complex option possible, which is high-fiber foods, and keep the starches to a minimum. In other words, go for foods that are basically fiber and sugar, the two types of carbs that do the most for your body.
The fiber part is important here - sugar in this context means naturally-occurring sugar in fruits and vegetables, not candy. Because without the fiber, sugar is a letdown, physiologically speaking.
Exceptions do exist, like marathon runners and distance bikers who need fuel for hour two of the race, but exceptions are rare. Most of us just need more veggies and whole grains to help our body perform optimally.