A refrain of eating disorder treatment is your body knows how to function. Give it enough food and it will take care of itself. The saying begins to be trite the more often one hears it, but the challenge is to recognize how profound it really is. Ultimately, believing this simple message can help someone with an eating disorder discount the majority of what any eating disorder thoughts deem as true.
Food is a biological necessity for life, as crucial as oxygen, water and sleep. However, of these absolutes, only food is so mutable to allow for someone to attempt to constantly manipulate and adapt their food choices.
The confusing messages society consistently supports is that one's diet is something to work on and perfect. There's a widely accepted belief that choosing food wisely, if not perfectly, will transform weight and health, if not the course of life itself. Meanwhile, the body will digest, absorb and utilize the energy from food in its own way no matter what one eats. Weight is a data point the body manages for health and wellbeing. And the vagaries of daily life are not related at all to what one decides to have for lunch.
The best argument to use against exaggerated, if not magical, thoughts about food and diet is that food is a basic necessity of life. Biology dictates what our body needs and how it functions. Our life course and decisions are what we can all try to affect and move through. Expecting food choice to fix life's problems means ignoring one's realities. And our lives need as much attention we can give them.