Before you try to put on weight, you should check if you’re underweight for your height. If you are, the best way to gain weight will depend on what caused you to lose it. You may also need some medical treatment.
Get advice
If you think you’re underweight, you should get advice from your GP. They can check if you’re a healthy weight for your height. You can also try our healthy weight calculator.
Why have I lost weight?
Losing weight without trying to do so can have many causes.
If you’re underweight for your height, your GP can check for any health condition that may have caused you to lose weight, for example:
- overactive thyroid gland, or
- a condition that prevents your body from absorbing food properly, such as coeliac disease.
Eating disorders, such as anorexia nervosa, can also cause people to lose weight.
You can find information about these conditions in our Health A-Z.
Gaining weight
To gain weight, you need to eat more calories than your body uses each day. You need to do this regularly. It's not enough just to have the occasional extra snacks.
Your GP can also give you advice about eating healthily and making changes to your diet, to help you gain weight.
Anorexia nervosa
If your GP thinks you have anorexia, you will need an overall assessment of your health. This assessment may also involve other healthcare professionals.
Treatment for anorexia usually includes:
- psychological treatment (talking to a therapist or counsellor), and
- advice on eating (your diet and nutrition) to help you gain weight safely.
These treatments work better when combined, rather than on their own.
Your healthcare professional will give you advice about how to increase the amount you eat so you can gain weight safely. They will help you to re-establish or develop healthy eating habits, so that you can:
- eat more food,
- eat more healthily, and
- increase the nutrients and calories you get from the food you eat.
You may also need to take supplements, such as multivitamins or multiminerals.
Our Health A-Z section has more information about treatment for anorexia.
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