What the heck are shirataki noodles made from?

And why does Dr. Oz call shirataki noodles one of his best "99 Diet Foods"?

By now, you've probably heard of shirataki noodles.  But did you know shirataki noodles and rice are made from a member of the yam family native to Asia called Konnyaku (Amorphophallus Konnyaku)? Products made from this root have been eaten in Japan and China for thousands of years. Konnyaku is naturally low in calories and carbohydrates; and high in fiber making it very weight loss and diabetes friendly. 

Made in the USA, Skinny Noodles & Rice Shirataki items contain at least 3 grams of fiber per serving to help you feel full and satisfied without extra calories and carbs. Use them in place of pasta, rice, potatoes, or bread. They also are Dr. Oz approved! He has listed shirataki noodles as one of his best "99 Diet Foods."