Losing weight=running faster

I just read in my latest edition of Runner's World that for every pound of weight you lose, you shave two seconds off a mile. So that means that the reason I haven't been able to PR in two years is the extra pounds I've packed on. That kind of makes me angry, but kind of encourages me to know that I'm technically probably still as fast as I was when I raced my best times, only there's a little extra thigh and belly holding me back. Unfortunately, I've been eating complete crap lately, so I'm only getting slower. Theoretically, if I lost 20 pounds I'd be able to shave 4 minutes off my 5K time! That's pretty crazy. But I don't want to lose 20 pounds, because then I would actually look like a runner (no offense to people with traditional "runner's bodies," I'm just not really into the super-lean build. I don't think it would suit me). I kind of like being a "thicker" runner-- I think it throws off my competition and gives me a leg up (haha, no pun intended).