A few years ago I found some diet/workout regimen online that i decided to try, I forgot the name but this guy wrote a whole book. It involves eating barely anything, like 1200 calories and no carbs during the week, and lifting low weight, high reps during that time. Insane gorging(like 6000 calories) and heavy lifting on the weekends.
Anyway during the first monday workout I was on my 500th set (or what felt like it) of light weight and I suddenly started to feel light headed, incredibly weak and incredibly nauseous. Ran to the the gym locker room and spewed hardcore in the bathroom, and almost passed out. Horrible experience.