Managing weight gain
BMJ Group Medical Reference
This information is for people who have anorexia. It tells you about managing weight gain, a treatment used for anorexia. It is based on the best and most up-to-date research.
Does it work?
Probably. Doctors agree that getting advice and support from professionals can help you put on weight. But there hasn't been much research about the best way to do this.
Research does show that people with anorexia and the staff treating them prefer a more relaxed approach to gaining weight, rather than a strict approach.
What is it?
Getting advice about eating to gain weight is an important part of treating anorexia.  You will probably be seen by someone who has training in treating people with eating disorders. This might be a nurse with specialist training, your GP, a psychiatrist, a dietitian, or a psychologist. What treatment you get depends on the clinic or hospital where you're treated. All doctors and other staff may have their own programmes for treating people with anorexia. But your treatment might include some of the following. 
You will probably be asked about what you have been eating and whether you have been making yourself sick ( vomiting) and using laxatives. This helps dietitians work out if you are likely to have low levels of vitamins, minerals, and other essential nutrients.
You will probably be weighed and your body mass index (BMI) will be calculated.
The aim is for you gain 0.5 to 1.0 kg (1 to 2 pounds) a week.
To gain this amount of weight, you'll need to eat between 2,200 and 2,500 calories every day. That's not a lot of food. It's about what a healthy adult eats every day, on average. But you may start eating much less than this, and slowly work up to this amount as you get used to eating again.
You'll be probably given advice about what you should be eating to gain the weight you need to. You might be given a meal plan with options for what you can have at each mealtime, plus what snacks you should have.
You will be given vitamin and mineral supplements if you need them. For example, taking calcium supplements may help keep your bones strong. 
You will probably be monitored closely at first to check your body is handling the extra calories and that you are putting on weight.
It can be hard for someone who has been starving themselves to just start eating again. That's why most people with anorexia will also have talking therapy at the same time. To learn more see Psychotherapy.
In the UK, the National Institute for Health and Clinical Excellence (NICE), the government body that advises about what treatments should be available in the NHS, says that advice on diet should not be used on its own to treat people with anorexia.  They should also have psychological therapy to talk about their eating behaviour and their attitude to weight and shape. To learn more about the kind of treatment you might get for anorexia, see What you can expect from the NHS.