Antidepressants were the third most common drug prescribed in the United States between 2005 and 2008, according to the National Center for Health Statistics. In addition to their ability to treat depression, many of these drugs can affect body weight. Some antidepressants, such as amitriptyline and other tricyclic antidepressants, tend to produce weight gain, whereas other antidepressants have no consistent effects on weight. Some may even help reduce weight, although the amount of weight lost is generally small and the loss is usually temporary. Bupropion is the only antidepressant that has been associated with sustained weight loss that persists after the first few months of treatment.
Bupropion (Wellbutrin, Aplenzin or Zyban) combats depression by increasing the amount of two proteins -- noradrenaline and dopamine -- in the brain. These effects may also contribute to weight loss, as both proteins are involved in the regulation of appetite, feelings of fullness and eating behaviors. Indeed, no other antidepressant increases both noradrenaline and dopamine, which may explain bupropion’s unique weight-related effects. Weight loss may also be due to nausea or vomiting, although these symptoms are usually not a prominent side effect of bupropion.
Bupropion: The Evidence
Initial studies conducted before bupropion received Food and Drug Administration (FDA) approval reported that 28 percent of people lost more than 5 lbs while taking the drug, according to Daily Med. A review that compiled the results of 116 studies, published in the October 2010 issue of “The Journal of Clinical Psychiatry," reported that bupropion was the only antidepressant associated with weight loss during both short-term use -- up to 3 months -- and long-term use -- at least 4 months. The average short-term loss was 2.5 lbs, and long-term loss was 4 lbs. Similarly, a study published in the April 2016 issue of the “Journal of Clinical Medicine” compared the effects of several antidepressants to fluoxetine, and found that only bupropion produced weight loss with long-term treatment. The average weight loss after 2 years of treatment with bupropion was 7 lbs, which only occurred in nonsmokers.
Several other antidepressants may produce temporary and less pronounced weight loss. In “The Journal of Clinical Psychiatry” review, the following drugs were found to produce short-term weight loss, lasting up to 3 months: -- Selective serotonin reuptake inhibitors: citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft). -- Serotonin and norepinephrine reuptake inhibitors: duloxetine (Cymbalta), venlafaxine (Effexor). -- Other: moclobemide (Amira). The average amount of weight loss was highest with fluoxetine -- 2 lbs -- and second highest with sertraline -- approximately 1 lb. Weight loss was lowest with moclobemide and paroxetine -- approximately ½ lb with each. None of these medications produced sustained weight loss when continued for 4 months or longer.
When considering the effects of antidepressants on weight, note that research only provides information about people who participated in the studies. The real-world effects in a specific individual may be quite different. Antidepressants may not only directly affect weight, but their effects on depression can have an indirect role as well. Many people with depression will reduce their activity level and either eat more or less. Successful treatment with antidepressants can reverse these changes, leading to changes in weight.
Even with bupropion, the average weight loss is less than 10 lbs. To achieve more substantial weight loss, other strategies will be necessary, including following a healthy diet, avoiding excessive intake of calories and participating in regular exercise over a prolonged period of time. Your doctor and dietitian will help you determine the safest and most effective approach to weight loss in your situation.
Depression may lead to many problems, including suicide, if inadequately treated. Seek immediate medical attention if you feel very depressed or have any thoughts of harming yourself. If you are taking any antidepressants, see your doctor if they do not appear to be effective or are causing side effects. Bupropion tends to produce fewer side effects than many other antidepressants, but it can increase the risk of seizures, high blood pressure, angle-closure glaucoma and psychiatric symptoms such as hallucinations. The FDA has issued a warning that all antidepressants may increase the risk of suicide, especially when used in children, adolescents and adults younger than 24.
Excessive weight loss, especially if it is unintentional or more than expected, may be due to an underlying medical condition that requires treatment. See your doctor if you suspect that you are losing too much weight.