i caught something from my kids and have really not felt like pushing my body. i made the mistake (or perhaps not...) of doing bikram yoga last monday, and my wednesday had a full-blown sinus infection. it's better now (lots of garlic and cayenne, apple cider vinegar and neti pot - i don't like drugs), but haven't been able to really exercise. just starting to get back into it, but sleep is more important right now. don't worry about calories, your body is slowing down it's metabolism anyway to recover so if you reduce calories you'll slow it down even more. just eat when you feel like it.
i do notice that anytime i lose weight from not eating due to illness, it comes right back on when i start eating again. i've observed the same thing of my clients and heard the same thing from friends. so don't be bummed if you gain the weight back when you get better, it's normal!