I don't really have a black or white answer, but consider this; if a person serves and loves food to the point that they receive pleasure and fulfillment from it, it can very well be idolatry(seeking pleasure, peace etc. from something other than God).
However eating disorders can stem from many things, and I am not naive enough to just slap the Jesus will fix it badge on it. It may be the outworking of many other issues going on in that person.
I've seen people go overboard with not eating because they were worshiping the idol of beauty. But behind that was also the idol of acceptance with man, and a desire to want to be wanted due to previous abuse and neglect from a parental figure.
We could go to illogical extremes with this view of not damaging the Lord's temple. For example, too much caffeine is not good for you, too much sun is not good for you, heck even sitting in front of a computer monitor isn't really good for you for long periods of time.
So, if you are the one struggling with this, you might want to see someone who is trained to handle it. Pastors are not doctors, and often they give some very poor advice.