If you or someone you love has been diagnosed with bipolar disorder, there’s a good chance lithium has come up in conversation. It’s been around for decades, and is still one of the most effective medications for stabilizing mood swings and preventing those intense highs and lows. In fact, for many people, lithium is a game-changer.
But while the benefits are real, let’s talk about the elephant in the room: weight gain. It’s one of the first things people ask when they’re prescribed lithium—“Will I gain weight on this?” or more bluntly, “Does lithium make you gain weight?” And the short answer is: it can, but not always.
The good news? There’s a lot you can do to manage it—and this blog is here to walk you through it. We’ll talk about why weight gain sometimes happens with lithium, what’s actually going on in your body, and most importantly, how to feel more in control of your health while still getting the mental health support you need.
At PsychPlus, we help people every day find balance with the right care plan—one that supports both mind and body. You don’t have to choose between feeling emotionally stable and physically well. Let’s dive in.
What Is Lithium and Why Is It Prescribed?
Let’s start with the basics—what exactly is lithium? No, it’s not just something found in batteries (though you’ve probably heard it there too). In the world of mental health, lithium is a mood stabilizer that’s been used for decades—primarily in the treatment of bipolar disorder.
If you or someone you know has experienced the intense ups and downs of bipolar—those euphoric highs followed by crushing lows—you know how exhausting and disruptive it can be. Lithium steps in to help smooth out those mood swings, making life feel more steady, more manageable, and a whole lot more peaceful.
It works by balancing the chemicals in your brain, and for many people, it’s a life-changing medication. One patient once shared, “It felt like the volume in my head finally turned down. I could breathe again.” That’s the kind of relief lithium can offer.
But like all powerful tools, it comes with a few trade-offs. One of the more common concerns people mention is weight gain. And yes, lithium side effects can include physical changes, especially when it comes to your metabolism, appetite, or fluid retention. We’ll dive into all of that soon—because it’s not the same for everyone, and it is manageable.
If you’re wondering whether lithium might be the right fit for you or a loved one, it helps to recognize early signs that bipolar disorder may be present. You can check out our guide on Recognizing Early Warning Signs of Bipolar Disorder Symptoms to learn more about what to look for and when to reach out for help.
Why Does Lithium Cause Weight Gain?
So, let’s address the big question: why does lithium cause weight gain?
If you’ve recently started lithium and noticed the scale creeping up—even though your eating habits haven’t changed much—you’re definitely not imagining things. This is one of the more commonly reported lithium side effects, but the good news is, it doesn’t happen to everyone and there are ways to manage it.
Here’s what might be going on behind the scenes:
🌀 Changes in Metabolism
Lithium can slow down your metabolism a bit. That means your body might not burn calories quite as efficiently as it used to. So even if you’re eating the same, your body might store more of it as fat. It’s kind of like your engine went from sport mode to eco mode—still running, just at a slower pace.
🍔 Increased Appetite
Some people notice they’re hungrier after starting lithium. Suddenly, snacks look more tempting, and portions quietly grow a little bigger. If you find yourself saying “Why am I always hungry now?”, it could be your medication nudging your appetite up a notch.
💧 Water Retention
Lithium affects the way your kidneys handle fluids. This can lead to your body holding on to more water, which shows up as weight gain on the scale—even if it’s not fat. You might feel a bit puffy or bloated, especially in your hands, feet, or facial area.
It’s important to know that not everyone gains weight on lithium—some people experience only minor changes, and others none at all. Our bodies all respond differently, and that’s totally normal.
If you’re starting to feel frustrated or worried about these changes, you’re not alone. Many people have walked this path—and you don’t have to figure it out on your own either. Lithium might come with a few hurdles, but with the right support system (including your healthcare provider), you can absolutely stay on track with both your mental and physical health.
Coming up next, we’ll look at what you can actually do to manage lithium-related weight gain without giving up the stability the medication offers.
How Common Is Weight Gain on Lithium?
You’re not alone if you’ve typed something like “Is weight gain inevitable with lithium?” into Google at 2 a.m.
The truth is, weight gain is a common—but not guaranteed—side effect of lithium. According to several studies, about 20% to 60% of people taking lithium experience some weight gain. That’s a big range because it depends on a bunch of factors: your dosage, how your body responds, your activity level, and even your genetics.
In real-life clinical settings, it’s not unusual to hear patients say things like:
“I felt better emotionally, but I didn’t expect the physical changes.”
Or:
“I was worried I’d gain a ton of weight, but it wasn’t nearly as bad as I feared.”
So, is it inevitable? Not at all. It’s just something to be aware of and proactively manage—which leads us to the next (and super important) part.
4. How to Manage Weight Gain on Lithium
How to manage weight gain on lithium without giving up the progress you’ve made with your mental health:
🥗 Stick to a Healthy, Low-Sugar Diet
Focus on whole foods—fruits, veggies, lean proteins, whole grains—and try to limit sugary snacks and processed foods. You don’t need to be perfect; just aim for balance. A food journal or app can help you stay mindful of your habits without getting obsessive.
🏃 Move Your Body—Even a Little Helps
You don’t have to become a gym rat. Walk the dog, dance around the living room, do some gentle yoga—whatever keeps you moving. Regular activity helps boost metabolism and can improve your mood, too.
⚖️ Keep Track of Your Weight—Gently
Check in with your weight every week or two, but don’t stress over daily fluctuations. Tracking can help you spot trends early and make small changes before things snowball.
🧠 Talk to Your Psychiatrist
Always bring up side effects—especially weight gain—with your provider. Sometimes, adjusting the dose or exploring alternatives can help. At PsychPlus, we encourage open, judgment-free conversations about how you’re feeling—physically and emotionally.
And if you’re unsure who to talk to or what type of provider to see, check out our guide on When to See a Psychiatrist or Therapist to help you figure it out.
Should You Stop Lithium Because of Weight Gain?
It’s a totally valid question—and one we hear often:
“If lithium is making me gain weight, should I stop taking it?”
Here’s an honest and gentle answer: Please don’t stop taking lithium without speaking to your doctor first. Even if the weight gain feels frustrating, quitting suddenly can lead to serious mood destabilization, including relapse or hospitalization in some cases.
We get it—feeling good mentally but struggling with physical changes can feel like a trade-off you didn’t sign up for. But here’s the hopeful part: bipolar medication and weight gain can be managed together. You don’t have to choose between your mental wellness and your physical well-being.
One of our patients once put it perfectly:
“At first, I felt like I had to choose—either be emotionally stable or fit into my jeans. But once I opened up to my psychiatrist, we created a plan that helped both. I didn’t have to choose after all.”
Your care team can help you find that balance, too. Whether it’s tweaking your dosage, adjusting your lifestyle habits, or exploring other treatment options, you do have choices.
Support and Next Steps
If you’re feeling overwhelmed by changes in your weight after starting lithium, know this: you’re not alone—and you don’t have to manage it by yourself.
It’s completely okay (and actually really helpful) to talk openly with a psychiatrist or mental health provider about your concerns. Whether it’s about weight, appetite, or any other side effects, these conversations are essential in making sure your treatment plan fits you—your mind and your body.
At PsychPlus, we specialize in personalized mental health care, including support for medication management and side effect concerns. We’re here to listen, guide, and adjust as needed.
👉 Book an Appointment today to speak with a provider who understands the balancing act between mental wellness and physical health. You deserve care that sees the whole you.
Conclusion
So, let’s recap the big picture:
✅ Yes, lithium can cause weight gain—but it’s not a life sentence.
✅ There are practical, sustainable ways to manage weight gain while staying emotionally stable.
✅ Most importantly, your mental health is worth prioritizing, and support is always available.
You don’t have to navigate this journey on your own. For more resources, real stories, and expert guidance on topics just like this one, be sure to check out the PsychPlus Blog. There’s a whole community here rooting for you.
