Remember, if it isn't about being transformed into the image of Christ, it isn't grounded in the Word!!)
"Support groups" don't help because "support groups", as such, are not biblical. In fact, "supporting" someone who is in sin is the least loving thing you can do.
Let that sink in a moment.
We are called as fellow servants of Christ to love, encourage, exhort, instruct, edify, build up and correct one another in the Body, using the Word of God as a plumbline. Galatians 6:1 is an excellent summary verse for how we are to help fellow Christians caught in addictions: "Brothers, if someone is caught in a sin, you who are spiritual should restore him gently. But watch yourself, or you also may be tempted." (emphasis mine).
Restoration implies change - biblical change. Sometimes this is forgotten, but change is always the goal of counseling - change in the direction of Christ-likeness. The last thing we want to do is support one another in a sinful lifestyle, if we love one another and love God. We should constantly be "spurring one another on to love and good deeds" (Hebrews 10:24).
Besides the fact that "support groups" (both secular and Christian) breed complaining and gossip about third parties, turning to non-change-oriented "support" systems (in expectation that other participants will either vindicate and coddle one's sin of choice) is contrary to what the Bible teaches. I have always had misgivings about such groups, but in studying biblical counseling and theology it has become even more clear how much damage such groups can actually do spiritually. Here is an excerpt from Jay Adams' "The Christian Counselor's Manual" that is germane to the subject of "support":
"First, Christian counselors must never support sinful behavior. (Contrary to some protestations, psychotherapists do define acceptance in ways that indicate approval of sinful behavior. Cf. the following: "His attitude is respectful, accepting, nonevaluative, noncondemning, noncriticizing...) If a counselee has failed to handle a problem God's way, what (s)he needs is not support for his faulty responses (or non-responses), but rather nouthetic confrontation. In nouthetic confrontation the counselor points out the biblical principals and through kindly, concerned conference seeks to bring the counselee to repentance, faith, and hope. It aims at change. Whenever the Spirit so blesses His Word, the counselee may then not only abandon his faulty and counter-productive methods of handling life's problems, but also turn to God's solutions instead. Whatever else a counselor does, at all costs he must avoid every suggestion that he is lending support to ways of handling life that do not originate with God. He simply may not by support "reinforce existing defenses," if these are contrary to scriptural injunctions.-- Jay Adams, "The Christian Counselor's Manual", pp. 156-157.
Secondly, support is harmful in that it not only acknowledges but also approves of the failure of the counselee to handle his problems. Offering support suggests that there are no better answers to the counselee's problems than those which he himself has discovered even though they may be manifestly unsuccesful. Such a realization probably was what led him to seek help. But, in short, support is not help. No help is extended. Indeed, support is offered in the place of help. It is an alternative to help. Because this is so, the Christian must recognize that support offered instead of direction from the Word of God represents Christ as a helpless Savior who has no better solutions than the counselee to life's problems.
Thirdly, there is no evidence in the Scriptures that a minister of the Word should stand by passively "being" but neither doing nor saying. Can you picture a passive Savior or a passive Apostle Paul?"
As a pastor I knew once said, "often, people come to counseling, but they don't really want help - they just want someone to listen and feel sorry for them." Being with others (fellowshipping) and "sharing" is not wrong in and of itself; we were called to bear one another's burdens. However, it should not (and must not) stop there. The answer lies in the Gospel -- not just for salvation, but for defeating the power of sin in our lives. This is as true for the bulimic or anorexic as it is for the porn star or drug addict. Jesus has provided the answer, but if we do not point ourselves and other struggling Christians TO that answer contained in His Word, we will stay stuck in a rut of defeat.
If you have an eating disorder and want to change, don't seek out "support" - it will help you stay where you are. Seek out accountability and godly counsel, and seek by God's grace and strength to be transformed!