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

Gaining weight is mostly the result of calories in and out. Some medications can alter how your body processes those calories, making you more likely to gain weight. Others can cause you to feel more hungry than usual, so you are likely to eat more calories than you would otherwise.

“Calories in, calories out” works for the majority of cases, but isn’t an absolute rule with no exceptions.