My two cents...I didn't do Optifast, but I started my journey with a Juice Feast that I did myself, not under supervision. That first week was **** and probably very much like Anne's experience. I sort of think of it as my body having a "WTF tantrum!" lol
Expect cravings to be extreme when you first start and expect the hunger to be a bit rowdy at times. I mean I was craving things I hadn't eaten in years! However, it does get better and if you feel it isn't, then you are able to consult with your doctor so that is awesome.