Just mix a container of vanilla yogurt (I use one that's fat-free or "light") with 1/2 cup of pumpkin puree. Add a little cinnamon or pumpkin pie spice. I also add one packet of Splenda to sweeten it more.
Half a cup of pumpkin is only 40 calories and has 5 grams of fiber! So, it adds alot of volume without adding many calories. In fact, if you are a "weightwatcher", the pumpkin will not add any points to your yogurt.
I had one can of pumpkin left over from the holidays. I hope I can find some more, I heard there's a shortage.