SSRIs can cause weight gain because they do affect metabolism.
Here is an except from
www.netnutritionist.com :
The Relationship between Weight Gain and Medications for Depression and Seizures
by Gay Riley, MS, RD, CCN
NetNutritionist.com
Are Americans now fatter than any other nation on the planet? This topic has been discussed, debated, and researched for the past 35 years. Americans continue to gain weight despite the billions of dollars that they spend annually on diets and diet foods. It is common knowledge that sedentary lifestyles, excessive consumption, and obsessive dieting are major factors in this trend. What else could be contributing to the skyrocketing obesity epidemic in the United States? Could the medications that some Americans take be a contributing factor in the obesity problem?
In the past decade, there has been an increase in the development and use of prescription medication to treat depression, seizures, and sleep disorders. Recently, we have also seen a rise in television, newspaper, and magazine advertisements for prescription medications led by the marketing of antidepressants, such as Prozac.
In 1999 Prozac, Zoloft, and Paxil were among the top 15 prescription medications dispensed in the US. Of the 124 billion dollars generated by the US prescription sales market, these three antidepressants were listed in the top 10 revenue-producing medications. Selective Seretonin Reuptake Inhibitors (SSRIs), Serotonin/Norepinephrine Reuptake Inhibitors (SNRIs), and antipsychotics were listed in the top 6 money makers of the 20 leading prescription products ranked by US pharmaceutical industry sales.
Current studies suggest that long-term use of SSRIs, Prozac, Zoloft, and Paxil is associated with weight gain. The purpose of this article is to list some of the popular psychotropic and seizure disorder medications on the market today and discuss the relationship, if any, these medications may have with body weight changes. A review of several studies regarding exercise and depression will also be reviewed.
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The information presented in this article is not intended to discourage, endorse, or recommend either treatment for depression or any of the products reviewed. It is intended solely as a review of the available information regarding weight changes associated with the products listed. As always, consult your physician or medical professional regarding any questions or medical conditions.
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Many people are not aware that weight gain is one of the most common side effects associated with many antidepressants prescribed today. In fact, medications such as Fluoxetine (Prozac®) and Buproprion HCL (Wellbutrin®) have actually been marketed for obesity treatment.
Antidepressants can affect weight in several ways:
They may increase or decrease basal metabolic rate without changing caloric intake.
They may affect hormonal changes and increase appetite.
Unexpected weight gain can increase the difficulties associated with psychiatric and seizure disorders by further aggravating mood instability and low self-esteem.
The following paragraphs contain brief descriptions of several classes of psychotropic and seizure disorder medications.
Selective Serotonin Reuptake Inhibitors (SSRIs)
SSRIs comprise one of the major classes of antidepressants currently being prescribed by primary care physicians. At first, SSRIs were thought to be associated with weight loss and reduced appetite. For a while, they were even marketed as anti-obesity drugs. It is now known that long-term use of SSRIs is associated with weight gain.
The reason that SSRIs contribute to weight gain is not known. Although it was a widely held belief that drugs that increase serotonin output also decrease hunger, this does not seem to be the case. Patients using SSRIs often report symptoms of hypoglycemia (weakness, dizziness, frequent hunger, and headaches) when they do not eat. Symptoms of hypoglycemia may indicate hyperinsulinemia (elevation of insulin in the blood).
The five most common SSRIs currently prescribed in the United States today are as follows:
Citalopram (Celexa®)
Fluoxetine (Prozac®)
Fluvoxamine (Luvox®)
Paroxetine (Paxil®)
Sertraline (Zoloft®)
Paroxetine (Paxil®) appears to have the most significant impact on weight gain of all of the SSRIs. Studies show that patients using Paxil experience an increase in breast size as well as weight gain and increased serum prolactin. One case report linked cravings for carbohydrates with Citalopram (Celexa®) while other studies showed an average weight gain over time of 15-20 pounds with Sertraline (Zoloft), Fluoxetine (Prozac®), and Citalopram (Celexa®).
However, SSRIs cause less weight gain, fewer anticholinergic symptoms, and less toxic adverse effects than tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs). These findings have led to the increase in SSRI prescriptions by psychiatrists and primary care providers. Primary care providers are not likely to be familiar with the difference between the various SSRIs relative to their possible weight gain side effects.
Tricyclic Antidepressants (TCAs)
TCAs were the most commonly prescribed antidepressants before SSRIs became widely available. Tricyclic antidepressants are often used to treat sleep disorders and to help patients manage pain. Most physicians are aware that TCAs can contribute significantly to weight gain.
Weight gain and other side effects vary from one TCA to another as well as from one patient to another. Many drugs in this class induce slowing of the metabolism and carbohydrate cravings. Factors more clearly understood involve histamine and alpha 1 receptor blocking actions. Appetite stimulation and weight gain make it extremely difficult for the diabetic using a TCA to control blood sugar.
TCAs include the following:
Amitriptyline (Elavil®)
Amoxapine (Asendin®)
Clomipramine (Anafranil®)
Desipramine (Norepramine®, Pertofrane®)
Doxepin (Adapin®, Sinequan®)
Imipramine (Janimine®, Tofranil®)
Nortriptyline (Aventyl®, Pamelor®)
Protriptyline (Vivactil®)
Trimipramine (Rhotramine®, Surmontil®)
Weight gain with TCAs is dose dependent and relative to the length of therapy.
The greatest weight gain among TCA patients has been observed with those using either amitriptyline (Elavil®) or imipramine (Janimine®, Tofranil ®).
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www.prozactruth.com/weight.htm