Friday, October 25, 2013

Sweet vs. regular potatoes

from http://www.precisionnutrition.com/

Potato types

Potatoes can also differ in their starch content and type, which affects not only how fast they’re digested, but how they act when cooked.
Floury or “mealy” potatoes, which have a fluffy texture and are thus ideal for baking or mashing, are higher in starch, particularly amylose.
“Waxy” potatoes have less total starch but are higher in amylopectin, which helps the potato hold together and gives it a slightly “gluey” texture. This makes them better for boiling. They also digest more slowly, especially if they’re cooked and then cooled.
Similarly, sweet potato types can vary in their texture, cooking properties, moisture, and sugar levels: White, yellow and purple-fleshed sweet potatoes are typically the dry type, while the orange-fleshed are moist.

Carbohydrates

Tubers are enlarged roots or stems that plants use to store nutrients. This is what makes them a good source of energy — in this case, starchy carbohydrates.
Tubers have been a food source for humans for millennia.

But in recent years, eaters have gotten concerned about carbs. People wonder about whether they should eat potatoes at all… aren’t they too “high carb”?

For one thing, “high carb” often isn’t the real problem.
Most people in North America, western Europe, and Australia consume potatoes in some processed form — as French fries, tater tots, or potato chips.
And in North America — especially in the Southern US — the phrase “sweet potato” is often followed by “pie”.

We typically slather spuds with other stuff, like butter or sour cream — and for our poutine-loving Canadian friends, gravy and cheese curds.
So the tubers themselves are not necessarily to blame. It’s all the stuff we serve them with.

Carbs and satiety

In fact, partially due to their carbohydrate content, potatoes and sweet potatoes are highly satiating foods.
You eat them, they “stick to your ribs”, and you feel full for a long time.
(There’s a reason that “meat and potatoes” is used to describe a satisfying meal.)
In fact, in 2010, Chris Voigt, the executive director of the Washington State Potato Commission, tried a crazy experiment: 2 months of eating only potatoes.

At first, he ate only when he felt hungry, and lost 12 lb in 3 weeks. To get enough calories, he then increased his intake to 20 potatoes a day… and he said he’d never felt so stuffed.
Despite apparently meeting his calorie needs, Voigt lost 9 more pounds throughout the rest of the experiment. Not only that, his blood measures (such as cholesterol, triglycerides, and blood glucose) improved.

Now of course, we don’t recommend the 20-potato-a-day diet. But Voigt’s results suggest — at least anecdotally — that in fact, starchy tubers are more satisfying and less fat-promoting than low-carb advocates might expect.
In part, this is because of the type of carbohydrate that occurs in potatoes and sweet potatoes.

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