i gained a lot of weight and i thought it was olanzapine BUT a doctor told me the lithium might be to blame for the weight gain and that surprised me..

lithium is a great medication for me (does any one NOT do well on it i wonder?? seems like a great med in general) so i will obviously stay on it

but im interested in the science of how much weight gain its causing and WHY its causing that weight gain??

like its not clear to me from this how much weight gain were really talking about: 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4730928/

&gt;Lithium is considered as the most effective maintenance treatment for bipolar disorder by virtue of mood stabilization, neuroprotective and antisuicidal properties.1) There are several adverse effects associated with long-term lithium maintenance therapy. Among others, impairment in renal concentrating ability, hypothyroidism, increased calcium and cognitive adverse effects need monitoring.2) Although not very common, weight gain is another adverse effect seen with chronic use of lithium.3–5) An early study had found that lithium maintenance therapy stimulated weight gains of over 10 kg in 20%, which was attributed to increased thirst in majority of individuals.6) In a recent meta-analysis, it was found that those receiving lithium had significantly more weight gain than the placebo group (odds ratio 1.89, 95% confidence interval [CI] 1.27 to 2.82; p=0.002).2) In a retrospective chart review, body weight gain with lithium treatment was 6.3 (standard deviation [SD] 9.0) kg, which was almost similar to that of sodium valproate (6.4 kg, SD 9.0).7) In comparison to lithium and valproate, weight gain with carbamazepine and oxcarbazepine is much lower.8,9) The pharmacological strategy for treatment of lithium-induced weight gain is not clear. We report a young male with bipolar disorder who had significant weight gain with lithium, which responded to metformin.

i see this too

https://www.verywellmind.com/lithium-the-first-mood-stabilizer-380282

&gt;Approximately 25% of people gain weight from taking lithium, according to a review article published in Acta Psychiatrica Scandinavica.1﻿ After analyzing all relevant published medical studies, the authors reported an average weight gain of 10 to 26 pounds among those who experience this troubling side effect.

&gt;Although the biological mechanisms that lead to lithium-related weight gain are not entirely clear, researchers speculate that several processes are likely involved. Additionally, several factors can influence the likelihood of gaining weight while you're taking lithium.