Eli5: If gaining weight is simply the result of calories in and out, then why does taking certain medications (birth control, anti-depressants) commonly lead to weight gain?

Question

Eli5: If gaining weight is simply the result of calories in and out, then why does taking certain medications (birth control, anti-depressants) commonly lead to weight gain?

In: Biology

Answer 1

Usually it’s because they change your body’s regulation of hunger and satiety. Essentially you get hungrier and feel less full for the same amount of food from before.

Some medications can also cause your body to hold more water that is would without that can cause minor amounts of weight gain.