While I think it's important to keep your calories generally in a healthy range, there are times when the body doesn't need or want food. I say don't fight it too hard.

I have had to force food down before, usually because I knew I could hit starvation mode and that would be awful. But if you're sick (whether you know it or not) you'll feel less hungry, and that's natural, normal, and most of all healthy--not eating allows your digestive system to rest and all that energy to go to healing. I'm a firm believer in therapeutic fasting, even though our society seems to think we'll all shrivel and die if we miss a few meals.

BUT--if this happens more than two or three days in a row, I would start to question the low calories and try adding at least some extra fat (esp. omega-3), and supplementing with vitamins and minerals, to make sure all the bases are covered.

That's my advice, anyway. If it's just a few days, don't worry too much about it. If it goes longer than that, start eating, and make sure EVERYTHING you eat has high nutrition in it. We don't actually need as much food as we often think we do, and if your body has plenty of fat to burn, you need nutrients more than calories for health.

There are some times the body is just catching up with high caloric intake too. When I was CKDing (carbing-up weekly), I found that the first 2-3 days after my carb-up (the carb-up was consistently very high calorie for the purposes of CKD), I didn't want to eat anything. Other days I was STARVING all day and couldn't seem to get enough to eat. The moral of the story: your body is probably figuring out how to regulate your caloric intake too, just don't let the low cal days get out of hand, okay?

Good luck, Julie! HTH!