If you're like me and hate to give up thickeners for gravy and stew, I've learned about the wonders of Zanthan Gum and Guar Gum.  Commercial companies use this in a lot of foods as a thickener, emulsifier and flavor binder.  You can get them in most health food stores (even in some high-end grocery stores), or in the food supplement sections of pharmacies, sometimes.  They're getting pricey, but package will last you a very long time!  Up side......they have NO CALORIES!  These powders can be lightly sprinkled on broth to turn it into a thicker gravy with no downside that I can see.  My brother the fussy executive chef says he thinks the texture of the sauce is "gelatinous" but I don't notice it enough to go back to calorie-laden flour & cornstarch.  And it's sure better than NEVER being able to have gravy or thickening soups.  But be careful, it thickens easily and only a tad is needed, so add slowly and wait until it thickens to see if you need more.  If you over do it when getting the hang of it, just add a tad of water to thin the gravy back down.  After using it a little while, you'll never use anything else to thicken gravy, soups, stews, etc.  I warn you if you spill it in water on your counter it's real slippery/slimy but cleans up fine. 

This is truly one of the best things I've discovered in my dieting "adventures".