Some antidepressants may cause weight loss, according HelpGuide.org. Make dietary changes to prevent weight loss if it is unwanted. If weight gain is significant, talk to your health care provider about whether your weight poses health risk. Your health care provider may suggest a dosage change or different medication.
Types
Types of medications used to treat depression include selective serotonin reuptake inhibitors, or SSRIs, atypical antidepressants, tricyclic antidepressants, or TCAs, and monoamine oxidase inhibitors, or MAOIs. SSRIs are the most widely prescribed and seem to work by blocking the reabsorption, or reuptake, of serotonin by certain nerve cells in the brain. Atypical antidepressants affect the neurotransmitter serotonin and sometimes norepinephrine and dopamine. TCAs inhibit the reabsorption of serotonin and norepinephrine by brain cells. To a lesser extent, they have the same affect on dopamine. MAOIs treat depression by preventing the enzyme monoamine oxidase from metabolizing the neurotransmitters norepinephrine, serotonin and dopamine in the brain.
Effects
Along with weight gain or loss, SSRIs can cause nausea, insomnia, anxiety, restlessness, decreased sex drive, dizziness, tremors, sweating, sleepiness, fatigue, dry mouth, diarrhea, constipation and headaches, according to HelpGuide.org. Serotonin and norepinephrine reuptake inhibitors, SNRIs, are atypical antidepressants that can cause loss of appetite and weight loss, along with anxiety and nervousness, headache, insomnia and tiredness, dry mouth, constipation, sexual problems, increased heart rate and increased cholesterol levels, according to FamilyDoctor.org. In addition to loss of appetite, the atypical antidepressants called norepinephrine and dopamine reuptake inhibitors, or NDRIs, may also cause agitation, nausea, headache and insomnia.
Medications
Loss of appetite and weight loss may occur when taking the antidepressants isocarboxazid, an MAOI, fluoxetine, an SSRI, sertraline, an SSRI, and bupropion, an NDRI, according to a 2002 study published by Yelena Vanina and colleagues in "Psychiatric Services." Zimelidine may also lead to weight loss, according to a 1981 study by R.J. Simpson in the "British Journal of Clinical Pharmacology." Zimelidine has since been banned.
Cause
The effect of isocarboxazid may be due to decreased overeating, according to a 1982 study published by Jonathan Davidson and Craig Turnbull in the "Journal of Clinical Psychopharmacology." Depression may result in weight gain. Weight loss on antidepressants may be because weight is returning to normal, states a 1984 study published by B. Harris and colleagues in the "British Journal of Psychiatry."
Time Frame
Weight loss with fluoxetine occurs primarily during the first four weeks of therapy, according to a 1999 study published by David Michelson in the "American Journal of Psychiatry." Patients who reported initial appetite loss tended to gain more weight throughout the year of the study. The first four weeks is the time that marked symptom improvement is expected. After four weeks, fluoxetine levels should be steady, suggesting improved depression symptoms and acclimation to the drug may play a role in weight loss.
References
- Help Guide: Antidepressants: What You Need to Know About Depression Medications
- Family Doctor: Antidepressants: Medicine for Depression
- Psychiatric Services: Body Weight Changes Associated With Psychopharmacology
- Journal of Clinical Psychopharmacology: Loss of Appetite and Weight Associated with the Monoamine Oxidase Inhibitor Isocarboxazid
- British Journal of Psychiatry: Changes Occurring in Appetite and Weight During Short-Term Antidepressant Treatment
- American Journal of Psychiatry: Changes in Weight During a 1-Year Trial of Fluoxetine
