Most people that i know seem to have gained weight on certain antidepressants, even when they’ve been eating the same and hitting the gym and claim to not be able to get rid of this weight no matter what they do.
What causes this? How do antidepressants change your metabolism?
In: Biology
Several things:
– most commonly used antidepressants (SSRIs/SNRIs) don’t cause statistically significant weight gain. Many people report subjective weight gain, but the numbers aren’t supported by data. One notable exception is paroxetine, which does consistently show some weight gain.
– there are other antidepressants that are widely known to cause weight gain, namely mirtazapine. This is presumed to be due to its effects on the histamine receptor. The medication is often chosen to help elderly patients who need to gain weight, so it’s not always an undesirable side effect.
– finally, meds from other classes – specifically antipsychotics and mood stabilizers – that are used to treat depression are known to cause weight gain. For unipolar depression, these meds are not first-line choices and are not indicated to be used alone; primary med usually still will be SSRI/SNRI. Bipolar depression is essentially its own disease entity that doesn’t respond to usual antidepressants; the medications approved for its treatment basically all cause weight gain.
– for many people, disrupted appetite is a symptom of depression. When the depression gets better, appetite improves.
– there are several neurotransmitters implicated in weight gain – notably histamine and very specific serotonin receptors – but we can’t study this directly. Essentially all antidepressants hit multiple neurotransmitter receptors, and we can’t reliably or easily tease out which does which.
– aging also decreases metabolism, but people generally want to attribute something like that to an external factor (the medication) rather than themselves/their body. For women in particular, estrogen significantly influences body fat retention as well as where weight is carried on the body.
– we are learning more about hunger, satiety, and how this influences and is influenced by weight with the explosion of GLP1 antagonists; I suspect we’ll soon have more quantitative data about how different medications affect our weight.
Hope this was helpful!
Source: am psychiatrist.
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