Please have a Knut. It will help.
Changing routine is easily one of the most distressing parts of dealing with an eating disorder, whether you're the person with the disorder or the person who has to be around them. For the anorexic, bulimic, or binge eater, having to change something that is comfortable is acutely anxiety-producing, and for the person/people around the patient, dealing with that anxiety (or trying to ignore it until it passes) can be maddening.
Tuesday and Wednesday decidedly do NOT make up my usual routine. Some helpful hints for eating disordered folks, and those around you, just as they pop into my head, to keep me busy while I try not to burst into tears over here. (I woke up Wednesday on the verge of tears I was so anxious, totally confused. "Why am I having an anxiety attack all of a sudden?" I asked myself. "Duh," I realized later. I mean, really. It's a little ridiculous.)
Tips for Eating Disordered People
Tip 1: Weighing yourself. Don't do it right now. Give it a few days, if you must do it at all. If the number goes up arbitrarily on this one day, it's not related to what you ate in the last 24 hours anyway (that's just not how it works).
Tip 2: You probably have a "problem area" that causes you more anxiety than most of your other body parts put together. DON'T TOUCH IT. PAWS OFF! In fact, put on the piece of clothing you have that makes you forget about that part most easily. For me it's the waist (as it is for so many of us), and I'm wearing a lovely Empire-waisted maxi dress today. Not perfect, but it helps.
Tip 3: Get out. Take a walk (with your billowy clothing on). It'll get your mind off things and let your body do one of its positives, move. Just remember - paws off. No grabbing at pieces you hate. If you're anorexic or an over-exerciser, time your walk and don't allow yourself to go over 30 minutes. (Don't go if you don't think you can limit yourself to that.)
Tip 4: If you run to anxiety before depression, like I do, remember to breathe. Standing up and nearly passing out does nothing but exacerbate anxiety, and unless you actually have a heart/blood pressure problem, it's the anxiety that's causing the dizziness. You don't have, say, a brain tumor.
Tips for Everyone Else
Tip 1: For the love of Knut the Polar Bear, people, don't go, "Wow, you ate that whole [food]." For the love of Knut, DON'T DO IT. IT WASN'T A VERY BIG OMELET AND I HATE YOU. *ahem* Sorry.
Tip 2: Actually, tip 1 pretty much covers it.