Ive found in the past when Ive been ill and lost weight its gone back when I started eating, I just always think its because youve not lost it as such, youre just totally empty so as soon as you eat again and fill your stomach youre going to gain.... probably not very scientific lol When my dad died I lost about 21lbs in 10 days because I couldnt eat and was sick everytime I did, once I started eating it went back on again quite quickly. Hopefully youll keep some of it off but Id be prepared for a bit of a gain next week.