How do antidepressants actually cause weight gain (or loss)?

LiveOnceBeHappy

I don't understand how antidepressants affect weight. I am taking Lexapro again, as of about 6 weeks ago. I don't know that it's affecting my weight yet. I understand it can cause weight gain or loss.

I get that it can cause increased appetite for weight gain. I get that it an cause a person to feel better and move more and lose weight. I don't understand if there's math involved overriding CICO. Is there a way that it can chemically change the math? I can control my calories and not allow myself to overeat. Is it going to change my CICO process though?

I've been on Lexapro previously and have tried a couple others too. I have been at a variety of weights but I don't know if antidepressants had anything to do with the different weights. I am at my lowest now and want to stay here or go a tiny bit lower. I'm 52, 128 lbs., 5' 2.5".

I've googled and cannot find the answer directly.

Thanks!

melbann

I've never been on antidepressants but my husband currently is. He has only been on them for about a year and a half so he has tried a few different ones in that time.

His previous one had a side effect of increased appetite. He has never watched his CICO. He gain 20+ pounds in the time he was on them. There were days he would eat a balanced amount of food but many times his appetite was insane. I remember there were times he would get up at 2 in the morning and eat 2-3 granola bars or pastries before he could get to sleep he was so hungry.

He is now on a different medication that has the side effect of appetite suppressant. Without trying he has lost the 20+ pounds he gained with the other one and many times doesn't finish his supper.

Maybe with watching your CICO you might not seem to effect you even if it really is?

Hollis100

Did you check the pharmacy papers that came with the medicine to see what they said about side effects? You might also ask the pharmacist if weight gain or loss is a side effect, or more specifically, how the med works. Good luck.

Lietchi

CICO is an equation. From what I understand, medication has an effect on weight through 3 mechanisms:

- increase in appetite (increase in CI of the CICO equation) -> calorie counting should limit this
- feeling more tired, listless, etc (lowering of the CO in the CICO equation): with a fitness tracker this might be something you could track and try to counter (but perhaps not fully, fidgeting for example also has an impact on CO, but hard to measure), either by attempting to get back to the previous level of activity or decreasing food intake accordingly
- water weight retention: this isn't a CICO thing, and I'm not sure how water weight gain can be avoided, except perhaps trying to find an alternative medication with less side effects

Xellercin

No one knows the mechanism of most side effects, but I can speak as someone who has been on many drugs that have weight gain as a side effect, not anti depressants, but several classes of drugs.

Some drugs make you sluggish, which lowers your daily calories out side of the equation. Some drugs make you obsessive about eating, so you snack much more. Some drugs make you more hungry, which is different from being obsessive about eating. Some drugs may modify how things are metabolized, so similar to how alcohol does this.

Nothing ever overrides CICO, but many things modify both the calories in and calories out sides of the equation.

For me, I was on a combo of beta blockers, Lyrica, and rounds of prednisone. All of which made it very difficult to control my intake as strictly, and lowered my daily calorie burn rate, which meant that when I didn't control my calorie intake as well, it was easier to gain and harder to lose.

Once I got off all of the drugs, I was able to start losing again, but my metabolism was so sluggish, it was a very, veeeery slow loss and I had no energy. Even being extremely strict with my calorie intake, I could only lose about 0.5lb/mo, and that could easily be regained, so it took me about 2 years to lose 5lbs, and I couldn't safely eat less, I was already chronically under eating a bit by that point.

So for me, it was the CO side of the equation that really messed me up. I was never binging or heavily over eating. Just eating normally was making me gain, and the drugs that gave me urges to eat made eating only 1200 calories a day impossible.

I didn't gain a ton of weight like most people on these drugs, but that's because I had already successfully lost ~80lbs before I started them, so I had a very, very good grasp on my eating. But even then, you can gain a lot over a few years just by having an excess of 100-300 calories per day. So between the lowered daily burn and a slight uptick in intake, that's enough to pack on the pounds if given enough time.

I was on meds for 2 years, so I only gained 25lbs. Had I stayed on them, it would have been a steady, slow crawl upwards. My sister in law was on one of my meds for a year and gained 70lbs because she couldn't control the urge to graze all day. I was working a job where snacking wasn't an option, but she's a stay at home mom with 2 kids who eat all the time.

How much the person gains will have a lot to do with how prepared they are to handle the urges to eat more. I had experience and structure in place to help me minimize the damage, but she didn't.

So the answer to your question is: it's complicated and there are a lot of factors at play. And CICO sounds simple but actually accounts for a massively complex metabolic system that is affected by countless things beyond just how many calories you eat.

Bridgie3

AFter the great NB of 2009 I had some time to play with antidepressants, my response would be

the citaloprams make it hard to get out of bed in the morning, and you gain not much weight
Wellbutrin (dopamine reuptake inhibitor) created anxiety that they fed you quetiapine for in tiny doses so you could sleep. That's basically a speed/downer relationship, I got a lot done but heart racing problems, irregular heart rythm, thought I was going to die. Still couldn't get out of bed in the morning, the quetiapine is a sedative. Also I slept in one position all night so my back ended up suffering.
mirtazipine - I put on 20lb in a month. I didn't know it, but I was dishing up huge amounts of food, and eating often. So I stacked it on without even realising. Couldn't get out of bed in the morning.
Sertraline: couldn't sleep for a week as I acclimatised to it but from then on was fine. easy to get up in the morning, no crazy appetite.