Weight Gain on Lithium

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I’ve been on lithium for nearly 2 years since I was diagnosed with bipolar.

background: always slim. Bit of weight gain when had kids but lost afterwards. Mental health fell off a cliff during lockdown when I lost my usual routine, which was doing a better job of keeping me away from the cliff edge than I realised. Put 4 stone on during lockdowns and afterwards, as mental health continued to crumble. Hospitalised with episode of hypomania in summer 2023. Put on olazapine and then lithium. Tapered off olazapine once lithium established. Lost 2 stone. Had a bit of wobble after a year when lithium levels went a bit low. Since then have put on 3 stone.

So overall 5 stone overweight. I lost the 2 stone in the middle without thinking about it and I’d hoped once I was back on even keel that would happen again but it hasn’t. I know weight gain can be a side effect of lithium but I’m not sure why. Is it hormonal (like steroids etc) and therefore weight gain inevitable or is it that is messes with my appetite and I’m actually just overeating without realising? I hate being so fat that it’s uncomfortable bending down to do my shoe laces up. I am active at gym, running and walking but the scales are still ticking upwards. I’m in early 50s so I’m sure perimenopause is adding itself to the mix.

Does anyone have some knowledge or experience of getting weight off when on lithium. Weight loss drugs aren’t compatible with lithium.

As yet I’ve no personal experience. But I’ve have been given the option to try lithium or quetiapine for bipolar 2. My psychiatrist has warned weight gain could be a prominent side effect for me via increasing my appetite. (Currently also have an ED.). My research seems to point to both drugs increasing your hunger (food noise?) so yes, in effect you end up over eating. Strictly watching what you eat and the ever important exercise seems to help. I would hazard a guess that if either drug makes you feel sleepy, exercise may also feel like too much of a chore, so increased appetite and less exercise would result in weight gain. But (good news?) it isn’t inevitable, and some people report being able to lose weight after the initial gain.

unfortunately, as we age we require less calories. Which doesn’t help.

Thanks for your reply. All the best with whatever option you go with.

I have found lithium works well for me in every other way and no other side effects. I do think I’m trying to still eat like I did in my 30s! I am managing to exercise - CrossFit classes - but I’m not walking or running like I used to and often snooze in the afternoon now I’ve given up work - so that won’t be helping. I have always struggled with food - comfort eating - I’ve just always kept ahead of it by being busy I think. If it’s just overeating, I can tackle that. I think I was drinking more water to begin with as I was worried about getting dehydrated so I wonder if that reduced my appetite. I’ll give it a go again.

wishing (unmumsnetty) all the best. Sounds like a good plan to increase fluids as that gives you ‘feel full’ signal to not eat and cannot hurt!
maybe be strict and write down everything that passes your lips in 24 hours and any activity you do - might help you pinpoint those sneaky comfort calories where you might be able to swap your food options for lower calorie options. I definitely cannot eat like I used to either!

I have been taking lithium for about 5 years now. Like you I was taking with olanzapine initially and I gained about a stone. Lost most fairly quickly when olazapine was stopped without any real effort. I believe there are a few speculative mechanisms for weight gain with lithium - possible effect on serotonin which can lead to appetite changes. We know it can cause hypothyroidism which itself leads to weight gain. The neuromuscular side effects - muscle weakness, tremor and fatigue also make exercise a bit more effortful for some people. Obviously kidney stuff such as increased thirst, salt cravings, associated water retention may also contribute. Probably all these things combined result in gradual weight gain for some people although we all tend to gain weight over time anyway. I have definitely found it more manageable compared to anti psychotics where you are fighting insatiable hunger. Personally I find exercise helps but also a more low carb /high protein fat diet works (not keto though). I also find running easier than weights or yoga - I think the lithium has impacted coordination/balance subtly but could be overthinking it. So in sum, I think it does have some effect on weight for some people but shouldn't be a huge barrier to weight loss. Obviously keep an eye on blood monitoring. Your plans sound very reasonable and achievable. Good luck.