Konnyaku is a wonderful food for anyone on any kind of diet - provided, of course, that you like it. I do like it - it has a very unique chewy-bouncy texture. I have described konnyaku and its noodle-shaped cousin, sharataki, before, but briefly, konnyaku is a grey to white colored, gelatinous mass which basically consists of water and fiber. It has almost no calories. Right out of the package, konnyaku and shirataki have an odd smell, but if you treat it properly (directions given below) you can get rid of that and just have the flavorless yet curiously interesting mass of goo that is going to fill up your belly in a very useful way.
This is something very easy to make in a jiffy. It's basically taking a classic Italian spaghetti recipe and applying it to konnyaku. You could make this with shirataki too, in which case it will actually look like noodles, but I rather prefer the chewier texture of konnyaku. The only thing to watch for if you are on a diet is the amount of olive oil and optional cheese you use.