There are many medical reasons for being underweight. Before trying to put on weight, you need to know that it is safe to do so. The best way is to make sure you are supervised by someone appropriately qualified.
See if you're a healthy weight for your height by checking your BMI.
If you're underweight, your doctor can check for any health conditions that may have caused you to lose weight, such as:
- an overactive thyroid gland (hyperthyroidism)
- type 1 or type 2 diabetes
- coeliac disease, a condition that prevents your body from absorbing food properly
- eating disorders, such as anorexia nervosa
- body dysmorphic disorder
Once the cause of your weight loss has been found, your doctor can give you advice about making changes to your diet, sometimes with the help of a dietician.
The type of food you will need to eat to put on weight will depend on what is causing you to be underweight.