No. I went through a computer nerd spree where my diet was coffee and oatmeal for breakfast, oatmeal for lunch, and jacks links plus diet coke for dinner. Went from 185 to 155 in two months. Got a scrawny hillbilly six pack with veins showing up in my shoulders and pecks. Didn't work out. Then a few months later I started eating and lifting and found my max bench went from 265 to 155, and I was winded on stairs. But the point is, eating a little didn't seem to upset the fast. At the time I rationalized not working out cause the previous time I ate so little I found myself prone to injury and to quit exercises one by one until I was basically just going for a walk. Make sure you get a feast once in a while and do work out.