Dear Dr. Wes and Jenny: My sister “M” has decided that she is fat. She is less than 100 pounds, 5 feet 1 inch tall and 100 percent muscle. Six out of seven days a week she is either working out, at the gym for gymnastics or at the gym for cheerleading. Her idea of losing weight is to 1) take laxatives; 2) take water pills; 3) eat less than 300 calories a day; or 4) exercise excessively (as if she doesn’t already?). She has taken herself off her depression medication and lies to her dietitian, doctor, family and therapist.

We’ve reached a point where we just don’t know what to do. Her mood is constantly changing up and down, she hates our family (that consists of my dad and me), and we don’t do anything to cause that. And to top it all of, she just wants out of this world. If “M” could get out of this house, she would in a heartbeat, and there’s absolutely nothing wrong with our home. I just don’t know what to do. Is there any advice you can give? Please help.

— 16-year-old girl

Wes: Clearly you understand how serious this situation is. I am less clear if the professionals do, especially if “M” is still fooling herself and everyone else so easily. You haven’t used the term in your letter, so I will. Among other things, your sister appears to be anorexic. There is evidence that genetics, society, school, media and family dynamics all play a role in this disorder, and I suspect there are several of these at play with “M.”

However, the most important thing to know about anorexia is not how it starts — but how it ends. Malnutrition causes the body to deteriorate, and eventually every major organ system may malfunction. Heart muscle mass, chamber size, and output decrease. In the worst-case scenario, patients may die of starvation, though they are typically hospitalized first and forced to eat. Well before they hit bottom, people with anorexia go from being obsessed with weight to being psychologically incapable of rational thought, dropping into a delusional state of denial about their body image, nutrition and health. This is why they don’t listen to anyone’s good advice.

Worse, “M” appears deliberately engaged in “suicide on the installment plan.” I suspect a fundamental problem here is that “M” is involved only in individual therapy. I was trained that no person with anorexia should be seen alone because they are never honest. You, your dad, friends, boyfriend, etc. all should be involved in her treatment, and you must be willing to tell the truth about what she is doing. This will not win you any popularity contests, but “M” is very ill and she needs her family to pull her through this, even though she does not see that. If you don’t have a direct connection to her therapist, you need to get one. Something is not working here, and you are a wise young person to raise these questions.

Jenny: “M” seems to be slipping away into nothingness. Even though your family is trying to help her, she doesn’t see that. From what I can tell, your family has recognized she has a problem because she is seeing a dietitian and a therapist. I question why these professionals can’t see past the excuses that most anorexics make and truly help her. It is never good to lie to a therapist because then they can’t truly help you. If you feel that she isn’t telling the truth to those professionals, then you or another family member needs to. Taking a personal involvement in her life, whether it is monitoring her eating, exercise or making sure she takes her antidepressants, will make a huge difference, even if you have to treat her like a child.

You may be scared about taking a firm action to help your sister because she will probably be mad at you, but down the road she will be more appreciative. It is like the anti-drug commercial where a friend is drowning and there is a girl on the dock watching her. Your sister is the girl drowning, and you need to throw her a rope by keeping track of her and talking to the professionals about what is really going on. I know that there is a lot of pressure to be thin in high school, especially if you are 5 feet 1 and 100 pounds and most likely a “flyer” in cheerleading. But she needs help in facing those pressures, not just giving into them and letting them control her.

She also needs to realize there are people who want to help her, and you need to show her that by getting help. You have taken the first step, and I am proud of you. Now you need to throw her the rope so she can get back to being herself again. Start by clipping this column and giving it to her. Maybe if she realizes how much your caring comes through in your letter, it will help.

Wes Crenshaw is a board-certified family psychologist and director of the Family Therapy Institute Midwest. Jenny Kane is a senior at Free State High School. Opinions and advice given here are not meant as a substitute for psychological evaluation or therapy services. Send your questions about adolescent issues to doubletake@ljworld.com.