I think our bodies become accustomed to whatever we put in it. Remember "Super-Size Me"? He interviewed people who were somehow able to eat fast food every day. I also think eating unhealthy foods will eventually catch up with you in a big way.
When I recently switched to a more healthy diet, I experienced a healing reaction for a few weeks. Flu symptoms, fatigue, etc. I just finished my first Liver Flush this weekend.
Maybe you should approach this in layers like I did, starting with improving your diet, Liver Flush soon after. You are heading in the right direction now!