I bought some yams at the market yesterday, but now I wonder if they are actually yams (they were labeled yams). The bin had all sorts of sizes, from wine bottle sized to regular baking potato sized. The flesh inside is firm and orange. The skin looks like typical potato skin. My nutrition scale said the yam I weighed was 408 calories...and reading up, it looks like yams have more calories than sweet potatoes, so I am at a loss as to how to count it. Adding to the confusion, the market had a sweet potato bin, these were much smaller tubers with lighter skin.
True yams aren't very easy to find in the USA. Unless you bought it in an ethnic grocery, it's probably not a real yam at all, but rather a variety of sweet potato that is often called a yam (but really isn't).
In the USA most tubers sold as yams are actually sweet potatoes. It's possible you got a "real" yam, but fairly unlikely.
They look fairly similiar, but true yams tend to be shaped more like tubes, and have more round or blunt shaped ends. Sweet potatoes are more potato shaped (that is they have more tapered ends, sometimes even pointy).
So if it has pointy ends (or at least one pointy end) - or is short and potato shaped - it's probably a sweet potato
If it has round ends, and is long and more tube shaped - it's probably a yam
In the U.S. typically the terms are used interchangeably (regardless of what is correct horticulturally). Many people call the orange fleshed ones sweet potatoes in some parts of the country while in other parts they are called yams. In actuality they are almost always sweet potatoes as kaplods mentioned (although the flavor is VERY different in my opinion between white sweet potatoes and orange sweet potatoes)
The varieties around here the yellow/white fleshed potatoes are called sweet potatoes while the bright orange fleshed ones are yams. Where I grew up it was different which makes for some confusion when I send dh shopping
Truthfully ALL produce can have varieties in caloric content. I looked up sweet potatoes on 4 different sites and got fairly wildly different numbers. The age of the vegetable, the specific variety, where it is grown, how long since it has been picked, how much sun etc. all affect the sugar, starch and water content of produce. I think the orange ones tend to be a little more caloric than the yellow, but also tend to have more vitamins. Like most predominantly starchy foods, it is all ~ 100 calories/100 grams. give or take.
p.s. the white/yellow ones are FABULOUS roasted and can be more easily substituted for normal potatoes but just better , the orange ones have a more intense flavor that is harder to pass over on people who are afraid of trying new things.
My understanding is that, as ennay said, the terms "sweet potato" and "yam" are used interchangeably (and that more often than not, even if the produce is labelled as yam in a store, it is probably a sweet potato).
I could live on potatoes alone - I love them. But I learned not to eat them in large quantities and I substitute white potatoes (or I should say yellow flesh potatoes because I hate the true white potatoes) with sweet potatoes. Sweet potatoes have a lower glycemic index than white potatoes although, IMHO, the difference is not that big.
I just have to say I'm excited that people pointed this out. Hehe. I have a degree in horticulture and this is one of my "fun facts" that I love to point out. Just like the fact that most of our berries aren't berries at all.
Well then, the "yams" are definitely not yams (no matter what the supermarket thinks) and I'll just go with weighing them as sweet potatoes on my scale (a bit of a calorie variance is not big deal for me for the moment, they are so yummy and filling...great steamed in the microwave with some fat free low sodium chicken broth and then mashed, very filling)! Thanks for all the input!
Help! Yam, or sweet potato?
