I find that symptom to be the most damaging and difficult to deal with: the feeling of being fine. When I feel like that after not eating/not sleeping for two days, that's when I know in my head that I'm not; but it's also when it's the most difficult for me to convince myself to act differently. The apathy towards actions that you know are good for your body is so difficult to suppress. That's when I try to take a few minutes to practice mindfulness, i.e. feeling my body, breathing deeply, smelling, tasting, touching, etc. When I do that, sometimes my appetite suddenly returns or I suddenly feel the weight of exhaustion. Sometimes it doesn't work and I have to force myself (if I can). I hope you get what you know your body needs (even though it isn't telling you right now).