Does Taking Prozac Cause Weight Gain?


Antidepressants have long been associated with weight gain.  When Prozac (fluoxetine) first arrived on the scene in 1988, many doctors and patients were hopeful that it might alleviate this problem.  Unlike older antidepressants – such as the tricyclics (TCAs) and monoamine oxidase inhibitors (MAOIs) – it affected mainly serotonin receptors.  Because of this fact, it was hoped that it would not have the same adverse effects, such as dry mouth, drowsiness, and weight gain.


Unfortunately, it didn't work out that way.  While Prozac did not have side effects which were quite as severe as the older antidepressants, it did emerge over time that weight gain could still be a problem.  Although many patients initially did lose weight with this new medication, many would eventually regain those pounds, and some patients would ultimately gain weight if they remained on the antidepressant for a long time

And, Prozac is not alone in causing this dreaded side effect; all antidepressants can potentially lead to weight gain.

Why Prozac Causes Weight Gain

It is not known for certain why Prozac causes weight gain, although it is believed that it may somehow affect a person's appetite or metabolism.  It has also been speculated that some people gain weight simply because they were not eating well while they were depressed and the antidepressant has caused his or her normal appetite to return.

What You Can Do to Lose Weight on Prozac

Unfortunately, there is no magic bullet to help patients lose weight gained while taking Prozac.  The same options for weight loss exist as for those who have gained weight for other reasons:  healthy diet, regular exercise, and weight loss drugs. 

In addition, two experts, Elizabeth J.

Wurtman, Ph.D. and Nina T. Frusztajer, M.D., suggest that eating a high carbohydrate diet, which they outline in a book called The Serotonin Power Diet: Eat Carbs -- Nature's Own Appetite Suppressant -- to Stop Emotional Overeating and Halt Antidepressant-Associated Weight Gain, can be particularly helpful in eliminating weight gained while using antidepressants.  They believe that eating "therapeutic" amounts of carbohydrates can shut off excessive appetite by causing more serotonin to be produced.

Other Options for Dealing With Weight Gain on Prozac

If none of the above work for the patient, another option is to simply change to a different antidepressant.  Certain antidepressants are less likely to cause weight gain than others.  In addition, different people may respond in different ways to the same medication.


Blumenthal, Sarah R. et. al.  "An Electronic Health Records Study of Long-Term Weight Gain Following Antidepressant Use."  Journal of the American Medical Association.  Published online ahead of print:  June 4, 2014.  American Medical Association.

Ferguson, James M.  "SSRI Antidepressant Medications: Adverse Effects and Tolerability."  The Primary Care Companion - Journal of Clinical Psychiatry.  3.1 (February 2001):  22-27.

Nihalani, Nikhil.  "Weight Gain, Obesity, and Psychotropic Prescribing."  Journal of Obesity.  2011 (2011).  

Weil, Andrew.  "Why Do Antidepressants Cause Weight Gain?"  Andrew Weil, M.D.  Published:  February 11, 2011.  Weil Lifestyle, LLC.  

Wurtman, Judith.  "Reversing Antidepressant Weight gain."  Psychology Today.  Published:  July 26, 2010.  Sussex Publishers, LLC.