How do antidepressants cause weight gain?


Title says it all. Some antidepressants are more well known for weight gain, some aren’t. What is it about certain formulas and what happens in the body? Do you just get in a happy bubble and stop caring? Or is it more scientific?

In: Biology

I can’t tell you how but I can tell you that antidepressants do not put you in a happy little bubble. At their absolute best, they make you your normal self again.

ELI5: If you are sick, and the doctor gives you medicine, the medicine eventually makes the symptoms stop, right? You start feeling better. But it doesn’t give you super powers, or make you feel amazing (beyond just being happy/relieved you’re no longer sick). Same for an ointment on a cut, painkiller for a headache, etc. They put you back to your “normal,” they don’t make you better-than-normal.

It depends on the medication, but the 2 that I’ve seen cause weight gain were caused by increased water retention.

A side effect is increased appetite. It won’t make you gain weight, but you will find yourself eating more if you don’t pay attention.

It’s different for everyone. I think it’s a possible side effect for many, many medications, but that doesn’t mean it WILL happen for you. In fact if you eat to self-sooth, you may find that when you feel less awful, and are able to go out and do more, you end up eating less.

I know plenty of people who avoid anti-depressants or birth control, or whatever important drug, because they are scared of weight gain. It’s different for everyone. And antidepressants work differently on everyone.

So if anyone is considering taking one, but worried about side effects. The only way to found out is to take one with the supervision of a good doctor, and let them know if any side effect is really too much. Fatigue in the beginning is common, but if it’s been months and you can’t get out of bed, then you need to switch to another drug. There are lots to try, and you have to find the one for you.

There’s not really an ELI5 but you might think of these drug molecules more like big keyrings full of multiple keys at receptor sites rather than ONLY the keys for doors we want to unlock (like the ones making you depressed by staying locked). Some drug molecules float over and unlock the doors we want (sad mood door, low energy door, etc), and others float over and have unintended effects by unlocking other doors (sleepy door, dry mouth door, constipation door, increased appetite door, blood sugar regulation door, etc). The drugs with the most keys on the molecule open the most different types of doors and sometimes that’s good; in fact, some of the most powerful psychiatric drugs are very “dirty” in how they work on so many different types of receptors (doors). Also, even beyond keys and doors, relieving depression may make you more likely to enjoy pleasurable activity, such as eating, so you will tend to eat more, and gain weight simply because of that.

Increased appetite, that’s what makes people gain weight. The drug doesnt alert your body, it just makes you hungrier.

I’m not sure the mechanism behind it but my doctor, Dr. Huxtable, gave me an antidepressant that made me very sleepy, and when I woke up I was pregnant.