A few years back while doing the Atkin's Diet I started drinking Michelob Ultra instead of Harp, Bass, or any real beer. I continued to do so, because when I got off the diet, I realized my tolerance had risen, haha. Now, every time I go into a bar and drink any type of tap beer, I get incredible headaches. I realize at times this can be caused by taps not being cleaned, but this happens all the time now. I'm somewhat stuck with bottled beer now and really miss a few pints of some nice dark beer.