I know I experience complete loss of apetite but eat something every six hours to stop your body from thinking that you're starving it! It will stall your weight loss. As for the headaches there can be a couple of culprits. Your body is detoxing and this can be one of the results. Are you drinking enough water? Did you cut out the caffeine, caffeine withdrawl can do the same thing. Most of this will stabilze out in a week or two.

Hope this helped!