Both have negative effects on the body. An eating disorder becomes a part of the way a person lives their life. It is hard to stop the unhealthy eating habits because in a way the person is dependent on it just like an addict could be dependent on drugs or alcohol. This dependency creates a cycle that is difficult to get out of especially if you cut the "substance" out completely. People can have many negative effects from withdrawal in some cases the body was so dependent on that drug that it shuts down and dies. With an eating disorder there are negative effects if you don't take the right steps to fixing it. If a person has been throwing up every time they eat their stomach has likely shrunk and all of a sudden deciding to eat 3 full meals would be too much for their body to handle.