Zoloft, Effexor and Serzone cause little or no weight gain, and Wellbutrin can actually cause weight loss. Naltrexone may help prevent weight gain when used with antidepressants, according to WebMD.
Selective serotonin reuptake inhibitors, medications that affect levels of serotonin within the brain, are the antidepressants that most commonly cause weight gain, states the New York Daily News. Another class of antidepressant medications, tricyclic antidepressants, are less likely to cause weight gain.
Another less common type of antidepressant, known as monoamine oxidase inhibitors, is also less likely to cause weight gain, according to the National Institute of Health. Phenelzine is the drug in this class most likely to cause weight gain, while isocarboxazid and tranylcypromine are less likely to have an effect on weight.
Researchers from Harvard Medical School have conducted studies showing that the average amount of weight gained as a side effect of antidepressant use is minimal, usually around 2 pounds. Subjects who used citalopram experienced the most weight gain. Some test subjects actually lost weight, so weight gain is not always a side effect of antidepressant use. The researchers recommend that people suffering from a specific type of depression known as atypical major depression avoid antidepressants known to cause weight gain because weight gain is already a symptom of atypical major depression and may be exacerbated by the antidepressant use.