Lithium is one of the most effective treatments for bipolar disorder and other mood disorders. However, many people who use it wonder if it causes weight gain , a frequently discussed side effect.
The reality is that not everyone gains weight with lithium , although it can happen in a percentage of those who take it, especially during the first months of treatment.
Why can lithium cause weight gain?
Weight gain associated with lithium does not have a single cause, but studies point to several factors that may play a role:
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Increased appetite: Lithium can alter the balance of neurotransmitters related to hunger and satiety, causing you to eat more without noticing.
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Hormonal changes: In some cases, lithium can reduce thyroid function (hypothyroidism), which slows metabolism and promotes fat accumulation.
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Fluid retention: Some people notice bloating or a feeling of "extra weight" due to water and sodium retention .
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Increased thirst: Lithium can increase thirst, and if this is quenched with sugary or high-calorie drinks, it contributes to weight gain.
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Reduced physical activity: fatigue or lethargy that may accompany treatment also have an indirect influence.
How much weight can you gain with lithium?
Studies indicate that between 20% and 25% of people taking lithium experience some weight gain , which can range from 4 to 10 kilos during the first months or years of treatment.
In many cases, weight stabilizes after the first two years , and some people even manage to reverse it with small adjustments to their lifestyle.
How long does this weight gain last?
Weight gain typically occurs during the first six months of lithium treatment and may continue as long as the medication is taken. However, when treatment is discontinued or adjusted under professional supervision, weight usually decreases gradually .
How to avoid or control weight gain from lithium
If you notice you're gaining weight, there are effective and safe ways to control it without stopping your medication:
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Maintain a balanced diet: prioritize fruits, vegetables, lean proteins, and whole grains. Limit ultra-processed foods and sugary drinks.
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Stay properly hydrated: drink plenty of natural water or unsweetened herbal teas to avoid fluid retention.
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Exercise regularly: walking, swimming, or practicing yoga for at least 30 minutes a day helps keep your metabolism active.
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Monitor your weight regularly: this way you can detect changes in time and adjust your routine if necessary.
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Consult your healthcare professional: if weight gain is significant, the professional may review the dosage, evaluate thyroid function, or consider alternative therapies.
Should I be worried about this effect?
Weight gain can be bothersome, but it doesn't mean the treatment is failing . The important thing is not to stop taking lithium without consulting a healthcare professional, as doing so can cause a serious mood imbalance.
In most cases, with a balanced diet and consistent physical activity, it is possible to maintain a healthy weight during treatment.
In summary
Lithium can cause mild to moderate weight gain in some people, especially at the start of treatment. This effect depends on many factors (such as dosage, metabolism, and thyroid function), but it can be managed with healthy habits and proper monitoring.
If you are taking lithium and notice changes in your weight, don't be alarmed. Talk to your healthcare professional . adjust the treatment and prevent side effects without compromising your mental well-being.
