It would be easy for anyone in favour of the right to die to hold up their hands in dismay upon hearing Mr Justice Peter Jackson's decision that a 32-year-old anorexic woman will be given life-saving treatment that neither she nor her family wants.

Here's an intelligent woman who is fully aware that she has a severe form of a potentially deadly disease who twice signed forms last year saying she didn't want to be given treatment to keep her alive. The woman, a former medical student, told the court that her life was "pure torment", and that she simply wants to be allowed a dignified death. Her family, who feel she has suffered enough and clearly love her, support her decision.

Instead, she will be force-fed – a process which, according to Dr Evan Harris, member of the British Medical Association's ethics committee, can last a year and will involve restraining and sedation. It might not succeed, and is itself life-threatening.

Even if "E", as the woman is known, survives this ordeal, her long-term outlook may not be great. She has the severest form of an illness that, when experienced in adulthood, becomes so entrenched with a person's identity that they often see no way out. Indeed, four years ago, I interviewed about 20 adult anorexic women and I was struck by how many believed they would never get better. Many didn't even want to. "There is a part of me that doesn't want to get rid of it. I do feel I can deal with things better if I don't eat enough. It's a bit like a drug," one 36-year-old woman told me. "I cannot imagine how I would function without my anorexia, despite the daily misery it causes me. It has become a place of safety and part of who I am," a 34-year-old woman said.

I put this testimony to an expert in eating disorders. She told me that if she offered anorexic adults a magic wand that would improve their relationship with food, she knows many would hesitate. The older the anorexic (most are in their teens), the stronger the identification with the illness, she explained. No wonder the most logical conclusion appears to so many to be for "E", who will presumably be aware of this, to be allowed to die now.

The problem is that anorexia, by its very nature, defies logic, making the anorexic mind irrational. Because it is traditionally an illness most likely to affect high-achieving, capable, academic people, this is easy to forget. But at its core, it is a need for control in response to an emotional state that feels completely out of control (in E's case, she was sexually abused as a child, unknown to her family). Very quickly, however, the person finds themselves feeling out of control, a slave to the compelling voice of anorexia that tells them they are undeserving of the pleasure food would give them and deserving of pain and suffering of starvation.

Right now, E's anorexia is at its strongest, and therefore her resistance is at its strongest. But anyone who does recover will tell you it was only possible because someone else took control and made decisions for them, usually when they were at their most defiant. Research carried out on anorexics who have been treated against their will found that every single person was grateful for this action having been taken. You could argue that the research was skewed as a result of it focusing exclusively on survivors, but the point is that enough people did survive to carry out the study and moreover, the results were overwhelming. As services for adult anorexics improve slowly, this is surely significant.

We must also remember that E is suffering from malnutrition, which affects a person's thought processes. As her brain is nourished as a result of force-feeding, the effect will be access to more critical judgment.

Here, most likely, is where those in favour of preventing people with serious illness choosing to end their lives will jump on their soapbox. "This is exactly what we mean when we say people who express a wish to die may change their view," they'll cry, backing the court's decision wholeheartedly.

But by hijacking this particular case to bolster their arguments, both camps are missing the point. This isn't about the right to die or providing life-sustaining treatment at any cost. This is about a unique illness that has a mental as well as physical component. Its ravaging effects on the body crucially affects the ability to think clearly. And, cruelly, it is that very ability to think that is necessary in order to make a genuine choice about recovery.