Antipsychotic medication and weight gain


This article, written primarily for people with mental health problems and their carers, is about weight gain with antipsychotic medication. Antipsychotics are a group of drugs that are mainly used to treat schizophrenia and manic episodes in bipolar disorder. In both conditions, they are effective in treating symptoms and reducing the risk of a person becoming unwell again (i.e. having a relapse). Some antipsychotics are helpful in other mental health disorders. Unfortunately, antipsychotics can cause side effects. One of the most common and serious is weight gain. People with schizophrenia are twice as likely to be obese than people in the general population.[1] Antipsychotic medication contributes to this. Other causes of overweight include physical inactivity, an unhealthy diet, other medications and the effect of some symptoms of mental illness. For example, depressed mood and lack of drive can make a person less active and contribute to weight gain. Overweight increases the risk of having a heart attack and stroke and developing many physical illnesses including high blood pressure, type 2 diabetes, sleep apnoea, osteoarthritis and some cancers. In general, the more overweight a person is, the greater their risk of developing these problems. Overweight is associated with reduced self-esteem, reduced quality of life and stigma. People taking antipsychotics regard weight gain as one of the most distressing side effects caused by their medication.

Risk of weight gain with different antipsychotics

The fastest weight gain occurs in the first 6 months after starting an antipsychotic. Weight gain can continue after this but more slowly.  There is no clear relationship between weight gain and antipsychotic dose, at least within the ranges usually used to treat mental health problems.2 Antipsychotics differ in their risk of causing weight gain, and other side effects, but do not differ in their effectiveness in treating symptoms of schizophrenia or mania. The one exception is clozapine which is more effective than other antipsychotics in treatment resistant schizophrenia. This is a form of schizophrenia in which psychotic symptoms (e.g. hearing voices) have not responded to treatment with at least two different antipsychotics.

The table shows the risk of weight gain with different antipsychotics. However, weight change can differ greatly from person to person. With any antipsychotic, some people may gain a lot of weight, some a moderate amount and some may not gain any weight or actually lose some weight. Greater weight gain during the first month of antipsychotic treatment tends to predict greater weight gain in the longer term. Antipsychotics can increase glucose (sugar) and lipid (fat) levels in the blood. The drugs that do this the most tend to be the same ones that cause the most weight gain.

Table: Risk of weight gain with antipsychotics (table adapted from BAP ‘Guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment’[2])
Antipsychotic Risk of weight gain
Olanzapine High
Clozapine High
Chlorpromazine High/medium
Quetiapine Medium
Risperidone Medium
Paliperidone Medium
Asenapine Low
Amisulpride Low
Aripiprazole Low
Lurasidone Low
Ziprasidone Low
Haloperidol Low

Starting antipsychotics for the first time

A person starting antipsychotic medication for the first time is likely to gain more weight than someone starting the same medication who has previously taken other antipsychotics. This is because weight will often have been put on with earlier antipsychotic treatment. In a study of people early in the course of schizophrenia, who received treatment for up to one year, approximately eight out of ten people prescribed olanzapine developed significant weight gain (defined as an increase of 7% or more of their starting weight).[3] This compared to about five or six out of ten people who gained significant weight when treated with quetiapine or risperidone. In a different study of people who had previously received long-term antipsychotics, and were followed for 18 months, significant weight gain (more than 7% of starting weight) occurred in one third of people who started olanzapine with rates about half of this for those starting quetiapine or risperidone.[4] Comparing the two studies shows that weight gain is more likely in people earlier on in their illness. This corresponds to people being treated by early intervention teams in the UK.

How antipsychotics cause weight gain

Weight gain is the result of taking in more energy (calories) from food and drink than are used up through the body’s resting metabolism plus activity and exercise. The extra energy or calories are stored as body fat. Many factors can affect this energy balance and lead to weight gain. The main way that antipsychotics cause weight gain is by stimulating appetite so that people feel hungry, eat more food and take in more calories.  Some people taking antipsychotics report craving sweet or fatty food.

The regulation of appetite and food intake is extremely complex and is controlled by part of the brain called the hypothalamus. The hypothalamus integrates information it receives from other part of the brain and from hormones released from outside of the brain including fat (adipose) tissue and the gut. These hormones include leptin and ghrelin but there are many others. Exactly how this complex system works and how antipsychotics disrupt it are not fully understood. Neurotransmitter receptors in the brain seem to play a part, with evidence implicating the serotonin 5-HT2C and 5-HT1A receptors, histamine H1 receptor and dopamine D2 receptor among others. Antipsychotics differ in their ability to block these receptors and this partly explains their different liability to cause weight gain. Both olanzapine and clozapine, drugs with a high risk of weight gain, bind strongly to the histamine H1 and serotonin 5-HT2C receptors.

The pharmacology of antipsychotics is not the only factor that determines their effect on weight. As already mentioned, if a group of people take the same antipsychotic there will be differences between them in their subsequent weight change. This reflects differences between people in their diet, level of activity and genetic makeup. Variations (polymorphisms) in a large number of genes, including the gene that codes for the 5-HT2C receptor, have been linked to susceptibility to gain weight with antipsychotics. It is the combined effect of these genes, rather that variation in a single gene, that is relevant to weight gain. Currently doctors and patients choose drugs partly based on their ‘average’ effects seen in clinical trials, for example the risk of weight gain as summarised in the table. In the future, it may be possible to conduct a simple blood test (i.e. a genetic screen) to identify a person’s likelihood to gain weight, and to develop other side effects, when treated with different drugs, so called personalised medicine. This could help people choose the best drug for their treatment. However, such a test is not currently available.

Managing weight gain with antipsychotics

Decisions on choosing medication and managing weight, as with other areas of treatment, should be made jointly by a patient and their doctor. The main approaches to managing weight with antipsychotics are:

  1. Ensure that the risk of weight gain, and other side effects, are considered when choosing an antipsychotic. Wherever possible use drugs with a lower risk of weight gain.
  2. Monitor weight and Body Mass Index (BMI) during antipsychotic treatment. More regular measurements are needed in the first few months of treatment as this is when the risk of weight gain is highest.
  3. Use lifestyle approaches to manage weight gain. These include increased physical activity, exercise and changes to diet and eating behaviours, for example eating regular meals, having smaller portions and cutting down on foods and drinks rich in sugar and fat.
  4. If weight gain with an antipsychotic is problematic, consider switching to an antipsychotic with a lower risk of weight gain. Depending on the drugs involved, this can lead to weight loss. The risks of switching include the new medication causing side effects and being less effective for that person, leading to a relapse of their psychiatric disorder.

Other approaches can sometimes help manage weight gain including adding certain medications to antipsychotics. These approaches are reviewed in a recent BAP Guideline that also considers the broader issue of reducing the risk of cardiovascular disease (i.e. heart disease and stroke) in people with psychosis.2

Some people may consider stopping antipsychotic treatment due to weight gain. The issue of how long to continue antipsychotic treatment is complex. Space only allows some basic comments to be made here. Excess weight caused by an antipsychotic will usually be lost gradually after medication is stopped. Weight put on for other reasons is likely to remain. The downside of stopping antipsychotics is an increased risk of becoming unwell, especially for people with schizophrenia and bipolar disorder. Sometimes relapse occurs suddenly with serious repercussions. A person should never stop their antipsychotic, or alter the dose, without discussing this first with their psychiatrist. Together, the patient and doctor should carefully consider the advantages and disadvantages of continuing medication, stopping medication and other options for managing mental health, weight gain and other side effects. These will differ from person to person and reflect their medical history and current circumstances. The discussion should lead to a jointly agreed management plan that is tailored to the individual. For some people stopping medication is a realistic option but for others it is inappropriate. If a decision is made to stop antipsychotic treatment, then the dose should be reduced gradually. Medication should not be stopped suddenly. A healthcare professional should monitor the person for signs and symptoms of relapse while the dose is reduced and after it is stopped. For people with schizophrenia or psychosis, monitoring is recommended for at least two years after antipsychotics are stopped.[5]

Recent and ongoing research

A great deal of research is trying to improve outcomes for people with mental health problems. This includes developing more effective medications with a lower risk of weight gain and other side effects. Lifestyle modification programmes have a modest benefit in reducing weight gain in people starting antipsychotics and helping those established on antipsychotics to lose weight.[6] An additional advantage is that these programmes can reduce lipid (fat) and glucose (sugar) levels in the blood. These interventions can be given to individuals or to groups or both approaches can be combined. A recent example of a group intervention is the STRIDE study in the United States.[7] In STRIDE, people who were overweight, had a serious psychiatric illness and were taking an antipsychotic were randomised to weekly two-hour group meetings for six months or to normal care alone i.e. a control group. Participants were encouraged to eat a healthier diet and spend at least 25 minutes per day doing moderate activity. At six months, 40% of participants (compared with 17% of controls) had lost at least 5% of their initial body weight and 18% of participants (compared to 5% of controls) had lost at least 10% of their initial weight. It is generally accepted that for people who are overweight, losing 5% to 10% of total weight has health benefits[8], though greater weight loss is more beneficial. The intervention in STRIDE was also effective in reducing weight and lowering blood sugar levels at 1 year i.e. after an additional 6-month follow-up period. The STEPWISE study is currently assessing the effectiveness of a group programme to reduce weight in people with psychosis taking antipsychotics across ten mental health NHS trusts in England.[9]

If psychosis, at least in some people, could be treated by giving antipsychotics for shorter periods than is current practice then it would reduce weight gain and other medication side effects. The RADAR trial is an ongoing randomised trial in the UK that compares a gradual and supported programme of antipsychotic reduction to maintenance antipsychotic treatment (i.e. staying on the current antipsychotic dose).[10] Within the dose reduction group, it is envisaged that some people will eventually stop medication whereas others will stabilize on a lower dose. The main outcomes in the RADAR trial are social functioning and relapse.

There is strong evidence that adding cognitive behaviour treatment (CBT), a ‘talking treatment’, to antipsychotic medication reduces symptoms of schizophrenia further and decreases the likelihood of rehospitalisation.5 Researchers have started investigating CBT as an alternative to antipsychotic medication to treat psychosis. This approach has the advantage of avoiding antipsychotic side effects altogether. This work is at an early stage and at the time of writing its effectiveness is not known, though initial results are promising.[11] CBT without antipsychotic medication, if proven to be effective, would not be suitable for everyone with psychosis. Nevertheless, it would widen treatment choice for some people and represent a major step forward in treating psychosis.


Antipsychotics are effective in treating schizophrenia and mania but can cause a range of side effects. Weight gain is a common and serious side effect, especially due to its impact on physical health. Various interventions can help and a psychiatrist will be able to offer advice on these. Many people taking antipsychotics can lose some weight with simple changes to their diet and lifestyle. Losing even a small amount of weight can have important health benefits. Ongoing research is attempting to find ways to better manage or ideally avoid this problem.

Further information

Body Mass Index: The best way to determine whether weight is ‘normal’, or should be regarded as overweight and unhealthy, is to calculate the Body Mass Index (BMI) using a person’s height and weight. An NHS online BMI calculator is available at:

The BAP Guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment are available at:

An article reviewing these Guidelines is available at:


[1] De Hert M et al (2009). Cardiovascular disease and diabetes in people with severe mental illness position statement from the European Psychiatric Association (EPA), supported by the European Association for the Study of Diabetes (EASD) and the European Society of Cardiology (ESC). Eur Psychiatry 24(6):412-24.

[2] Cooper SJ et al (2016). BAP guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment.  J Psychopharmacol 30(8):717-48.

[3] McEvoy JP et al (2007). Efficacy and tolerability of olanzapine, quetiapine, and risperidone in the treatment of early psychosis: a randomized, double-blind 52-week comparison. Am J Psychiatry 164(7):1050-60.

[4] Lieberman JA et al (2005). Effectiveness of Antipsychotic Drugs in Patients with Chronic Schizophrenia. N Engl J Med 353:1209-1223

[5] National Institute of Health and Care Excellence (NICE) (2014). Clinical guideline [CG178] Psychosis and schizophrenia in adults: Treatment and management [CG178]. Last updated: March 2014.

[6] Bruins J et al (2014). The Effects of Lifestyle Interventions on (Long-Term) Weight Management, Cardiometabolic Risk and Depressive Symptoms in People with Psychotic Disorders: A Meta-Analysis. PLoS One 9(12): e112276.

[7] Green CA et al (2015). The STRIDE weight loss and lifestyle intervention for individuals taking antipsychotic medications: a randomized trial. Am J Psychiatry 172(1):71-81.

[8] Wing RR et al (2011). Benefits of Modest Weight Loss in Improving Cardiovascular Risk Factors in Overweight and Obese Individuals with Type 2 Diabetes. Diabetes Care 34(7): 1481–1486.

[9] Gossage-Worrall R et al (2016). STEPWISE – STructured lifestyle Education for People WIth SchizophrEnia: a study protocol for a randomised controlled trial. Trials 17:475

[10] Registration information for the RADAR trial is available here

[11] Morrison AP et al (2014). Cognitive therapy for people with schizophrenia spectrum disorders not taking antipsychotic drugs: a single-blind randomised controlled trial. The Lancet 383(9926), 1395-1403.

13 thoughts on “Antipsychotic medication and weight gain

  1. My Sons weight more than doubled in the 5 years that he took Clozapine. He recently passed away and complications of obesity is noted on his death certificate. So much more work is needed in the control of weight gain in these poor souls who are already suffering enough

    1. I’m very sorry to hear about your son. Clozapine can sometimes help when standard antipsychotic medications haven’t worked, particularly in treating distressing psychotic symptoms. It’s very unfortunate that clozapine can also cause serious side effects. I agree with you that more work is needed to manage weight gain associated with antipsychotics. The recent ‘BAP guidelines on the management of weight gain, metabolic disturbances and cardiovascular risk associated with psychosis and antipsychotic drug treatment’ are one endeavour to help with this.

    2. I am a Special Olympic ski coach and one of my dear athletes is extremely overweight from his anti-psychotic drugs. He was recently told he could not stop his meds. I fear for him. I know his lifestyle is unhealthy too and was wondering if we just got him out walking a few times a week would help. Don’t want to overstep any bounds here but I just need to do something.

      1. Walking can help to lose weight. If you increase your physical activity you will burn more calories. If you burn off more calories than you consume through food and drink, then you will lose weight. Increased activity can be achieved in many ways, for example walking, using stairs in preference to taking a lift, taking part in sport or exercising at home or in a gym. The more intense your activity or exercise, and the longer it lasts for, then the more calories that are burnt. Of course, it’s important not to overdo things and activity levels should be built up gradually. Some people can’t take part in vigorous exercise and walking can be ideal for them. Walking is relatively easy to do. Many people find a walk relaxing and if done with others it can be sociable. Regular walking can have other health benefits including lowering blood pressure and reducing your risk of heart disease. Increased activity is more effective in helping to lose weight if it is combined with changes to diet i.e. consuming less calories.

  2. The weight gain from these medications is more detrimental than the illness (Bipolar II) I personally suffer from initially. The weight gain, irregular heart beat, increased blood pressure, sedation and god knows what else what other told they have taken on my body, they are just a horrific group of drugs that I wish the doctors prescribing them would take for a month just to suffer them so they wouldn’t just push them so freely onto people who are already at the depths of dispair!

    1. As you highlight both psychiatric illness and the side effects of antipsychotic medication can cause great distress. Good psychiatric care aims to ensure that people receive effective treatment, experience as few side effects as possible and are fully involved in decisions about their care.

      Shared decision-making by doctors and patients is recommended when choosing treatments. This means that the patient and their doctor discuss the range of treatments available. The doctor’s expert knowledge of each treatment, including its pros and cons, is brought to the table. The patient brings their experience of their illness, including symptoms they want to be treated and particular side effects they wish to avoid. A joint decision on what treatment to use can then be made. This allows treatment to be tailored to the individual. Patients are usually more satisfied when decisions are made in this way.

      As antipsychotics vary in their side effects it is usually possible to reduce side effects by choosing medication carefully. Unfortunately, side effects can still occur. When this happens, the doctor and patient need to carefully consider what to do next. This will depend on how they view the trade-off between the advantages and side effects of the current medication. It may be that the antipsychotic has had clear benefits, for example in reducing or eliminating symptoms of illness and allowing the person to manage better in their everyday life. They also need to consider how the current medication fares again any earlier medications that were used and medications and treatment approaches that have not yet been tried. If the person is well and contemplating stopping medication totally, then the risk of a recurrence of illness needs to be assessed; this will partly depend on the frequency and severity of any previous episodes of illness. When all this information is available, the patient and their doctor can consider the options and make a joint decision about what to do next.

      In some cases, it may be decided that a side effect is worth accepting given the benefits of the medication. In other cases, it may be clear that the side effect is intolerable and that the medication needs to be altered. Many side effects lessen when the dose of an antipsychotic is lowered but weight gain is an exception; the degree of weight gain is usually unrelated to the dose of an antipsychotic. Some side effects can be reduced by changing the time at which the medication is taken. For example, sedation may be less troublesome when medication is taken at bedtime rather than in the morning. Some side effects can be lessened by taking another medication to deal with them. Sometimes the best option to manage an antipsychotic side effect is to change to a different medication with a lower risk of causing that side effect. If the person has schizophrenia or psychosis then one will need to switch to a different antipsychotic. If the person has bipolar disorder then it may be possible to switch the antipsychotic to a different type of medication, for example lithium. This will depend on the person’s individual circumstances and medical history.

      A person should never stop or reduce the dose of their antipsychotic medication without discussing and agreeing this first with their psychiatrist. Stopping antipsychotics and reducing their dose are both associated with an increased risk of relapse i.e. a return or worsening of the underlying psychiatric illness. A period of close monitoring by a psychiatrist, or other mental health care professional, is needed whenever an antipsychotic is reduced in dose, switched or stopped. This is to ensure that the person remains well and that support and help are promptly available should there be any problems, including side effects or early warning signs of relapse.

  3. I am struggling on arirprizole, and my mood swings have not got better on it. They tend to be connected to my menstrual cycle. I am hungry all of the time and it makes me tearful. Despite not eating more on the medication, and going to the gym, swimming, eating healthily, I still have a great deal of fat on my body and people are telling me I look ‘well’, which is the usual euphemism for ‘a bit fat’. It is horrible. I want to do my job as an actor and I have lots of additional body fat that gets in my way when I am exercising.

  4. A very helpful article. I personally suffer from psychotic depressive episodes, for which I am prescribed a low dose of olanzapine. As you can see it is at the top of the weight gain list and I have put on about 4 or 5 stone over the 4 years I’ve been taking it. When I most recently stopped taking it, after a long period of stability, I became severely delusional about a month later, resulting in a hospital admission. So, I have concluded that I need to be on antipsychotic medication to keep sane. However, 3 months before the admission, I was using ketamine and magic mushrooms. So the recreational drugs may have had more of an impact than the lack of medication. Anyway, I am keen to lose weight so if anybody can offer advice on going drug free, switching drugs, or simply dieting and hitting the gym, that would be great.

  5. I have been on Divalproax for 3 yrs.I feel like a vegetable. Lathargic,loss of interest in everything, never happy,extreme weight gain.It’s easy for someone to tell patients to join a gym but how do we get there if we don’t have the energy to get out of a chair? Memory loss! What can I do ? I want to feel normal again. What started this was my addiction to alcohol.I havent had a drink in 3 yrs.anychance suggetions

  6. I have serious weight gain from quetiapine. I went from fit and slim 14.5 stone to 20.5 stones in about 5 months when I switched to the quetiapine. I find the biggest problem is carbohydrates. If I don’t eat them my huge belly swelling reduces quickly. Not the weight as a lot of it is muscle as well. I do find that cutting down on food in take works abut but I get very sore stomach that kicks in at about 4 am. I feel very shaky and this doesn’t go away until I get up and eat a really good breakfast. Even then it’s the same the next night and the next and my anxiety starts kicking in. I feel there is direct link between carbohydrates and quetiapine. If I remove the carbohydrates the swelling around my abdomen reduce dramatically but I start to feel down and everything is ok until that happens.
    The passive abdomen swelling is the biggest pain as I lose the weight the pain starts and vice versa. I eat very healthy and don’t touch sugary food or alcohol pretty much accept once a week.
    I once read that to go on a low carb diet in very bad while on quetiapine as it undermines the effectiveness of the medication. It’s like the quetiapine needs the carbohydrates to work and I feel that’s pretty much bang on.
    I don’t know if this is well understood but might bandage the prescription of these medicines if that link was better understood. It’s a shame because it stops people making choices and informed decisions if these relationship are not accepted.
    I’ve taken these meds for 20 years and have monitored exactly how I felt during this period. Every time I try to discuss this with my doctors I get the same answer . Don’t stop taking them. That’s why I don’t think they understand what is going on chemically with these meds and default to the same response.
    That’s ok until I finally get something nasty like diabetes or some other horrible condition. I normally do quite a lot of hard training and need food to keep me feeling fit and strong but the weight and the huge belly bloating just doesn’t go away until I remove the carbohydrates.
    I keep trying to lose the belly but it goes back to huge when I eat carbohydrates. There is the cycle. It’s bloody hard to take when before I took quetiapine I was pretty slim and had great difficulty actually putting weight on.
    A happy medium is what’s required. Either I take less meds or I find a way to stop the pain and be able to eat less carbs without upsetting the mental health balance.
    Any chance someone has good advice around this area.

  7. When medicines are prescribed surely it makes sense to understand the implications for that person so far as is possible. Including their physiology. I don’t think they know enough about these medicines. The only person who knows is the patient. I think they use hammers instead of nut crackers.

  8. Hi I was diagonised with acute pyschosis, after 4 months of gradual increase in intake of zyprexa(olanzopine) from 2.5mg to 20 mg I was able to get back to normal life, however,I gained weight like 13kgs in a span of 3 months, and I had issues with memory and drug induced sleep. I decided to quit medicines, however my psychaitrist wouldnt let me do that, I tapered it down by myself and gradually reduced it in a span of 2 weeks and stopped it. Its been a month now. I had lightheadedness for few days after medicines were stopped now I feel perfectly normal, I indulge in 2 hours of physical activities in a day and keep myself busy. Got back to my job too. Practising meditation helps. I have stopped gaining weight. its all about mental stength.

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