There are many reasons why you might like to gain weight. If you've been unwell or receiving treatment for a condition like cancer, it's not uncommon to lose weight, especially if you are unable to eat or you have no appetite. You might choose to put on weight for aesthetic reasons, such as someone who goes to the gym and wants to build more muscle.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/how-to-gain-weight-healthily