eli5 How do antidepressants and other medications cause someone to *gain* weight?

Question

eli5 How do antidepressants and other medications cause someone to *gain* weight?

In: 90

Answer 1

This is a bit of a loaded question as most common antidepressants aren’t actually associated with significant weight gain on average. Mirtazapine, paroxetine, and older tricyclic antidepressants like amitriptyline are exceptions.

Anyway, medications with the most weight gain frequently block receptors involved in appetite regulation, including certain histamine and serotonin receptors. Some drugs don’t increase fat gain but increase water/salt retention. Steroids like prednisone have a huge range of effects on how cells function and can cause shifts in where fat is stored along with weight gain. Appetite is really complicated and there are parts we don’t understand, but certain drug actions predictably increase weight and/or appetite.