The Subway diet I am on works effectively at keeping me from going overweight. It's relatively healthy, as far as fast food goes, and certainly better for me than the processed, tasteless $1 Banquet meals I used to shove down my may every day.
The key to making the diet work is restraint. I used to devour footlongs within seconds, then I discovered that if I stopped with one half I was no longer hungry. Stopping at six inches saves half the hassle, money and calories. Also, I never get a drink or chips. But I do redeem the free cookie coupon on the receipt every time.
It's a great system. I get an amazing lunch every day, I never get sick of it and do not get fat.