Dear DOCTOR Owen:

My doctor prescribed Prozac for depression and said that this drug might help with weight loss. Obesity in itself is depressing! I have a friend who swears that Prozac made her gain weight. What is the latest word on this issue? I will be more depressed if I gain weight.

Dumpy and Depressed

Dear “Dumpy”:

There has been conflicting information on this in the past, but new information is emerging all the time. The most complete review of this subject to date is found in Primary Psychiatry, Vol. 7, No. 5. The entire month’s issue was devoted to a review of this topic—the most comprehensive to date on the subject.

You raise a valid point. Your physician should be concerned about weight gain as a side effect of the Prozac. The emotional aspects of obesity could worsen your self-image and aggravate your depression. But my concern, as a physician of Internal Medicine, is what the weight gain might do to your health. People with a Body Mass Index (BMI) (see the Appendix in the back of this book) of 27 or above have a 72% chance of developing a chronic disease related to diet and weight. Such diseases and the medication required to treat them may cause depression. The cost of treatment is also depressing. Those are real problems—not just related to your appearance.

SSRIs (selective serotonin uptake inhibitors) are the most widely prescribed and most popular antidepressants ever used because they are highly effective and have a lower risk of side effects than the older tricyclic antidepressants. SSRIs improve serotonin levels in the brain, with improvements in mood and other symptoms.

Initial studies of these agents looked at the short-term (less than 6 months) effects of SSRIs on weight. The SSRIs appeared to be weight-neutral and, in some cases, induced weight loss in the first six months. In longer-term studies, the opposite occurred, with a trend of weight gain. Differences were seen between the individual compounds constituting the various SSRIs, but there was nothing to indicate that one was more weight-promoting than another.

SSRIs include Prozac (fluoxetine), Zoloft® (sertraline), Paxil® (paroxetine), Luvox, (Fluvoxamine) Celexa, Remeron, Serzone, and Effexor. New and improved SSRIs seem to enter the market weekly. Each claims to reduce the risk of weight gain more than the next but, in reality, few long-term studies exist. I can safely say that they do not reduce weight. I can further safely say that, in selected cases, clear and serious weight gain does occur.

Theoretically, those SSRIs that block the histamine receptor, and that cause dry mouth, constipation, or drowsiness, might be more likely to cause weight gain. Histamine, one of the most prevalent chemicals in the brain, has effects on many other brain chemicals.

Finally, researchers have shown the immediate effects of SSRIs are on the small number of serotonin-producing nerve cells at the bottom of the brain, located within emotional centers. The effect of the SSRIs on these nerve cells might cause weight loss initially. It has also been shown that long-term use of SSRIs is associated with a “sprouting” of these nerve fibers to grow like “vines” on trees. The nerve vines continue to form new “leaves”‘ and “flowers” over time. Therefore, you might expect different results, such as weight gain, over much longer periods of time. I do indeed see different side effects over time with these agents.

If the risk of obesity is greater to you emotionally or physically than the depression, a lengthy discussion with your doctor or psychiatrist is in order. Fortunately, many treatment options exist now, which were not available several years ago.