> There's more of it in your gut than in your brain (why do you think people on SSRIs gain weight?)
It's true most of it is in our guts, but the weight gain link seems a bit far fetched. In the gut, serotonin depletion leads to the feel of hunger and high levels of serotonin is where you get a diarrhea. If anything I would expect the opposite [1]
Rats are a decent model, but they aren't humans. From googling around, it appears that weight gain is a common side effect in most (all?) anti-depressants.
Why does the effect need to come from the gut? SSRIs mess with the reward systems in the brain right? Other drugs that do that affect weight. I lost a ton of weight on stimulants because they kill appetite.
I've seen some sources say in humans around 2% of the study group lost weight, while other studies support 25% of a target group reporting weight gain. Main theory for weight gain is that the higher extra cellular levels of serotonin slow down the metabolism. Fascinating article you've linked though, thanks for sharing!
It's true most of it is in our guts, but the weight gain link seems a bit far fetched. In the gut, serotonin depletion leads to the feel of hunger and high levels of serotonin is where you get a diarrhea. If anything I would expect the opposite [1]
1. https://www.ncbi.nlm.nih.gov/pubmed/7312891