the calories because they were prisoners in the Vermont penal system whose actions were closely monitored.
Sims did make his volunteers fat, but it was a lot harder than he expected. The process took four to six months and required feeding some of the men a staggering ten thousand calories a day. When Sims did the math he discovered that each man gained weight at a different rate, despite the fact that they were eating the same number of calories. Not only that: the men who had been thin before the study began needed almost twice as many calories to maintain their higher weights as they had to sustain their ordinary lower weights.
Sims’s experiment highlights the fact that each person’s metabolism has a kind of set point, a natural range. Trying to alter that range—making a thin person fatter, or a fat person thin—takes nearly superhuman effort and blows the calories in, calories out theory right out of the water.
Maybe one of the effects of anorexia is to reset a person’s metabolism to an unnaturally low range. Which might explain why it’s so hard for Kitty to gain weight, despite eating large numbers of calories. And why even a very minor dip in calories seems to make her fragile and volatile.
The next morning, as she gets ready to leave for school, I ask if she has her midmorning snack with her. “I always pack it,” she says. I tell her I want to see it. I’m not in the habit, these days, of checking up on her. But my intuition is rarely wrong. And it’s not wrong this time: Kitty says she forgot to pack it, just this once. She pops a protein bar in her bag and runs out the door. But will she eat it?
I want to lie down and weep with weariness. Our friends have been commenting on how good Kitty looks, how much happier she seems. “She’s doing so well!” they say, and I want to say yes, but she still wrestles with the anorexia every single day. Yes, but if we let up for a few days, she’d go right back down the rabbit hole. Yes, but she’s not safe yet. Nowhere near it. Before, the illness was visible on her face, in her body. Now only Jamie and Emma and Kitty and I know the real distance between how she looks and how she feels. “You must be feeling so much better!” they say. I muster a smile and say as little as possible, because I have neither the energy nor the heart to tell them the truth.
If you fall ill with pneumonia, the treatment is fairly straightforward: a course of antibiotics. And so are the signs of recovery. You’re recovered from pneumonia when you feel better, when there’s no fluid in your lungs, when your blood count returns to normal. Three simple measures.
But when are you recovered from anorexia? I mean really recovered, not the 90 percent of ideal body weight that insurance companies and many doctors hold up as a goal. Some doctors talk about weight restoration as a mark of recovery—getting a child back to the weight she was before she started restricting. The trouble is, teenagers are still growing. They’re supposed to put on weight even after they stop growing vertically. So the healthy weight for an eighteen-year-old is unlikely to be the same as it was for that same child four years earlier.
The whole question of target weight is complex and much debated. Experts in the field often refer to body mass index, BMI, as a measure of restored health. But BMI is a crude measure, a simple ratio between height and weight. It says nothing about a person’s body type. Athletes score high on the BMI chart because muscle weighs more than fat and tissue; you can be “normal” on the BMI chart and still lack enough fat and mass. Kitty, for example, now has a BMI of 18.8, which puts her—barely—into the “normal” category for her age on the BMI chart. By this one standard, she’d be considered recovered. But it’s clear to both Jamie and me that she’s not.
Dr. Beth says the best way to gauge a child’s weight is to plot her height and weight since birth, find her natural growth curve, and aim to get her back on it. It’s sensible advice, especially compared with the gobbledygook of BMI charts and percentiles of ideal body weight. It’s not always enough, though. Kitty at thirteen was