While we have become sensitized to worrying about weight gain caused by antipsychotics, this side effect does occur with standard mood stabilizers as well. Recently, a comprehensive literature review was published evaluating the weight gain liabilities of medications commonly used to treat bipolar disorder (Torrent et al., Acta Psychiatrica Scand 2008;118:4-18). Here is what they found.

Lithium. Weight gain occurs in about 25% of patients, and ranges from 4.5 to 12 kg over the course of long-term treatment. Possible mechanisms: fluid retention, increased appetite, or lithium-related sub-clinical hypothyroidism. Polydipsia may also contribute to Li-induced weight gain, particularly if the patient drinks large quantities of high-caloric beverages.

Valproate. Weight gain occurs in 20-25% of patients, and ranges from 3-10 kg over 3-12 months, but one study reported a mean weight gain of 21 kg in 11 of 22 epileptic women over 7 years. VPA may cause polycystic ovarian syndrome in women, which may in turn contribute to weight gain.

Carbamazepine. CBZ has been shown to cause moderate weight gain in studies of epilepsy, but this has been less prominent in studies of bipolar disorder.

Gabapentin. One study of bipolar patients reported a mean weight gain of 0.9-3 kg after 12 weeks of treatment.

Lamotrigine. In many large studies, lamotrigine has been shown to produce no weight gain.
Typical antipsychotics. haloperidol, molindone, loxapine, and pimozide cause little or no weight gain in most patients.

Atypical antipsychotics.
Clozapine. Approximately 50% of patients gain at least 10-20% of body weight over several years of followup.

Olanzapine. In short-term trials, patients have gained 2-3 kg over 3-4 weeks of treatment, and about 4 kg after 10 weeks. In head-to-head comparisons, olanzapine causes more weight gain than valproate, risperidone, or ziprasidone.

Risperidone. Studies vary. One study reported a 2.5 kg gain over 3 weeks, while another showed only a 1.4 kg gain over 12 weeks.

Quetiapine. One study reported a 12 week weight gain of 2.6 kg. Another study showed no difference in weight gain between quetiapine and valproate.
Ziprasidone. Little if any weight gain.
Aripiprazole. Little if any weight gain.

Antidepressants. The following can cause significant weight gain: tricyclics, especially amitriptyline and imipramine, the MAOI phenelzine (less so tranylcypromine), paroxetine, and mirtazapine.
Looking for practical information on weight loss strategies for your patients?

The May 2005 issue of TCPR reviewed weight loss programs and medications, including xenical, subitramine, bupropion, and dexatrim.