Medication for eating disorders blog 3: Medication and weight gain

WeightBy Deborah Etienne-Ward

One of the main concerns that our clients often face when considering whether to include medication into their treatment plan is “Will the medication cause me to gain weight?” This is a valid concern, and a possible side effect of medications prescribed to people with eating disorders. You can find more information on the effectiveness of the medications mentioned below for treating the different types of eating disorders in Blog1: Medication for Eating Disorders.

Anti-psychotic medication

The first type of medication to be addressed are anti-psychotics. Anti-psychotics are often associated with weight gain and an increased risk of type II diabetes (Zoler, 1999; McIntyre, McCann,&  Kennedy, 2001; Tschoner et al. 2007). This occurs when anti-psychotics are required to be used on an ongoing basis for people with disorders such as schizophrenia (McIntyre, McCann, &  Kennedy, 2001; Tschoner et al. 2007). Within the area of eating disorders, anti-psychotics are generally prescribed to those with Anorexia Nervosa. This is for the purpose of reducing obsessive symptoms, which might otherwise interfere with treatment and recovery. Therefore, in contrast to the long-term prescription of anti-psychotics when used for treating schizophrenia, the use of anti-psychotics for Anorexia Nervosa is limited to the short-term (Bissada, Tasca, Barber, & Bradwejn, 2008). As a result, the weight gain associated with anti-psychotics is less intense when being used to treat Anorexia Nervosa.

The research on weight gain associated with the use of anti-psychotic medication for people with Anorexia Nervosa has focused on a specific type of anti-psychotic called Olanzapine. One study reported on the weight gain experienced by two females that had taken Olanzapine during a hospital admission for Anorexia Nervosa. These patients experienced a weight gain of 1.2kg and 1.7kg over the course of their 14 week and 22 day admission respectively (La Via, Gray, & Kay, 1999). As these patients were in hospital for the purpose of gaining weight, it is likely that re-feeding also occurred. Therefore, it is difficult to know how much of the weight gain can be attributed to Olanzapine alone.  Nevertheless, both patients continued to use Olanzapine following their discharge from hospital. At follow-up both patients had maintained their weight 6 months and 4 months post discharge respectively. That is, despite continuation on Olanzapine, there was no further weight gain following discharge from hospital (La Via, Gray, & Kay, 1999).

Other research has found that taking Olanzapine whilst also attending psychoeducational groups for 10 weeks led to an average weight gain of 2.6kg (Powers, Santana, & Bannon, 2001). Specifically 10 out of 14 participants that completed the 10-week study had an average weight gain of 4kg. Four participants lost an average of 1kg. Due to the addition of psychoeducational groups it is unclear how much of the weight gain can be attributed to Olanzapine alone. Nevertheless, the research highlights that medication affects each individual differently. Furthermore, Olanzapine appears to result in a relatively small amount of weight gain when considering that the average weight gain of 2.6kg occurred over 10 weeks, and that people with Anorexia Nervosa need to gain weight in order to recover.

What we see from this research is that the weight gain associated with antipsychotic medication for Anorexia Nervosa is steady. Furthermore, the weight gain does not increase any faster than would be expected to occur in psychological treatment (specifically Cognitive Behaviour Therapy). Moreover, the weight gain does appear to stabilise. Lastly, whilst weight gain may be daunting, again it is important to remember that it is essential for recovery from Anorexia Nervosa.

Benzodiazepines (anti-anxiolytics/anti-anxiety medication)

Benzodiazepines are not commonly used to treat eating disorders, however, they are occasionally helpful to decrease anxiety associated with re-feeding in Anorexia Nervosa. Very limited research exists on the effect of benzodiazepines on weight gain and currently, as far as I am aware, there are no studies which have investigated the effect of benzodiazepines on weight gain specifically for people with eating disorders.

Of the limited research which has been conducted on weight gain associated with Benzodiazepines results have been mixed. Some research has reported diazepam (Valium) to have no effect on weight when taken for up to 4 weeks (Jokinen, Koskinen, Selonen, 1984). Other research has suggested that when taken in the longer term, a change in the dosage of diazepam (Valium) does affect weight (Frisbie, & Aguilera, 1995). Specifically, the research found that taking diazepam (Valium) for up to 10 months led to weight gain while cessation of diazepam (Valium) led to weight loss. This research had many limitations which make it difficult to interpret the validity of the results.

On the whole benzodiazepines are not generally regarded to be a psychotropic medication associated with weight gain (Masand, 2000). Moreover, when used for eating disorders they are generally only taken for a short period of time thus reducing the likelihood of weight gain associated with longer term use.

Antidepressant medication

Antidepressants are commonly prescribed to people with Anorexia Nervosa, Bulimia Nervosa, and Binge Eating Disorder. Weight gain due to the use of antidepressants is most significant when taking two types of older antidepressants known as Monoamine Oxidase Inhibitors (MAOIs) and Tricyclic antidepressants (Masand, 2000). According to beyondblue the most commonly prescribed group of antidepressants in Australia are newer generation antidepressants called Selective Serotonin Reuptake Inhibitors (SSRI’s). Some examples of SSRI’s include: fluoxetine, sertraline, bupropion, citalopram, and paroxetine. SSRI’s are much less likely to cause weight gain, especially if taken for less than six months (Masand, 2000). Research has suggested that only 4.2% of people taking sertraline and 6.8% of people taking fluoxetine for 6 months gain 7% or more of their body weight (Fava et al, 2000). Additionally, venlafaxine, another type of antidepressant known as a Serotonin and Noradrenalin Reuptake Inhibitor (SNRI), has also been suggested not to result in significant weight gain in the short term (Silverstone & Ravindran, 1999).

What does all of this mean?

In conclusion, it appears that whilst weight gain is a common concern for people when considering whether to include psychotropic medication into the treatment plan for their eating disorder there is not strong evidence to suggest that weight gain will occur. Each individual person will respond to medication differently. Moreover, research suggests that when these medications are used in the short term (which is common when psychotropic medications are prescribed to people with eating disorders) there is a low chance of weight gain. As was mentioned in a previous blog most people that try psychotropic medications report that they do not regret it. Therefore, if your GP or psychiatrist has suggested the implementation of these medications it may be worth a try.

Disclaimer: The information provided in this article is general only and individual advice regarding psychotropic medication should be sought from your GP or psychiatrist.


Beyond Blue. (2015). Medical Treatments for depression. Retrieved from www.beyondblue.org.au/the-facts/depression/treatments-for-depression/medical-treatments-for-depressionFrisbie, J.H., & Aguilera, E.J. (1995). Diazepam and body weight in myelopathy patients. Journal of Spinal Cord Medicine, 18(3):200-202.

Jokinen, K., Koskinen, T., & Selonen, R. (1984). Flupenthixol versus diazepam in the treatment of psychosomatic disorders: a double-blind, multi-centre trial in general practice. Pharmatherapeutic, 3(9): 573-581.

Masand, P.S. (2000). Weight gain associated with psychotropic drugs. Expert Opinion on Pharmacotherapy, 1(3): 377-389. doi:10.1517/14656566.1.3.377

Zoler, M.L. (1999). Antipsychotics linked to weight gain, diabetes. Clinical Psychiatry News, 27(2): 20.

McIntyre, R.S., McCann, S.M., Kennedy, S.H. (2001). Antipsychotic metabolic effects: weight gain, diabetes mellitus, and lipid abnormalities. Canadian Journal of Psychiatry, 46:273-281.

Tschoner, A., Engl, J., Laimer, M., Kaser, S., Rettenbacher, M., Fleischhacker, W.W., Patsch, J.R. & Ebenbichler, C.F. (2003). Metabolic side effects of antipsychotic medication. International Journal of of Clinical Practice, 61:1356-1370.

Bissada, H., Tasca, G.A., Barber, A.M., & Bradwejn, J. (2008). Olanzapine in the treatment of low body weight and obsessive thinking in women with anorexia nervosa: a randomized, double-blind, placebo-controlled trial. American Journal of Psychiatry, 165(10): 1281-1288. doi:10.1176/appi.ajp.2008.07121900

La Via, M.C., Gray, N., & Kaye, W.H. (2000). Case reports of olanzapine treatment of anorexia nervosa. International Journal of Eating Disorder, 27(3): 363-366.

Powers, P.S., Santana, C.A., & Bannon, Y.S. (2001). Olanzapine in the Treatment of Anorexia Nervosa: An Open Label Trial. International Journal of Eating Disorders, 32(2): 146-154.

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