First, this might help: See if this helps at all: http://paleohacks.com/questions/92959/nutrition-differences-in-different-varieties-of-sweet-potatoes#axzz1z6UFW9Zh

And the North Caroline Sweet Potato Commission

Everything you ever wanted to know about Japanese sweet potatoes - these by the way are the ones I eat 90% of the time. If eating sweet potatoes, any varieties, aren't inhibiting your goals in any way - the calories are close enough that I wouldn't stress about it.

Nerd Alert - the calories may be off due to a labeling error, thank you interwebs!

Americans have been making the mistake of calling sweet potatoes "yams." But there's actually a difference. It turns out sweet potatoes and yams are not even related. They are two different species of root vegetable with very different backgrounds and uses.

So why the confusion? The U.S. government has perpetuated the error of labeling sweet potatoes "yams." In most cases sweet potatoes are labeled with both terms, which just adds to the confusion. Since there are two types of sweet potatoes, one with creamy white flesh and one with orange, the USDA labels the orange-fleshed ones "yams" to distinguish them from the paler variety. Ok, so that sort of makes sense. But why call the orange-fleshed ones "yams" in the first place?

Sweet potatoes (Ipomoea batatas) come in two main varieties here in the States. One has a golden skin with creamy white flesh and a crumbly texture. The other has a copper skin with an orange flesh that is sweet and soft. All sweet potato varieties generally have the same shape and size -- they are tapered at the ends and much smaller than the aforementioned yams.

Americans have been calling the orange-fleshed variety of sweet potatoes "yams" since colonial times when Africans saw familiarities in them to the tuberous variety. The USDA decided to label them as "yams" to differentiate the two varieties.

Yams (family Dioscoreaceae) are native to Africa and Asia and other tropical regions. Yams are starchy tubers that have an almost black bark-like skin and white, purple or reddish flesh and come in many varieties. The tubers can be as small as regular potatoes or grow upwards of five feet long.

The word yam comes from an African word, which means "to eat." The yam holds great importance as a foodstuff because it keeps for a long time in storage and is very valuable during the wet season, when food is a scarcity.

The Japanese one is starchier than the orange Southern yams. If you compare the taste, you'll immediately recognize the difference. The orange yams taste a bit diluted, while the Japanese ones are denser. Those purple Okinawan ones even more so. There are differences among myriad sweet potato varieties, including taste, starchiness and the amount of beta carotene. And that shouldn't surprise you.

Im still confused, so what is the right value 86 calories or 132 per 100g?

Does the Japanese sweet potato diet even work since these potatoes are very caloric? And are these the same potatoes that I get in the Korean market? I buy them in the Japanese and Korean markets and they look the same..