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Researchers have found that individuals who took antidepressants for an extended period gained, on average, twice as much weight as those who had never taken them. Even with diet and exercise, this effect intensified over time.
Dr. Gabriela Lugon, a researcher at Del Mar Hospital and Pompeu Fabra University in Barcelona, noted, “We cannot simply prescribe antidepressants for their positive effects without considering this side effect.”
The so-called selective serotonin reuptake inhibitors (SSRIs) are the most common type of antidepressants, and their side effects include weight gain. Their action is based on increasing serotonin levels, a hormone that regulates mood.
While modern antidepressants work better and cause fewer side effects than older versions, they all exhibit drawbacks both immediately and over time. Common negative consequences of these medications include sleep and digestive issues, dizziness, sexual dysfunction, and weight gain.
What Did the Researchers Discover?
The scientists involved 6,352 adults from northeastern Spain, aged between 35 and 79, in their study. The team monitored them over six years.
Participants were divided into four groups based on their antidepressant use: those who had never taken them, those who started during the study, those who stopped taking them, and those who had been using them for a long time.
Throughout the study, nurses recorded participants’ weight, diet, exercise frequency, depression symptoms, smoking status, diabetes status, and blood pressure.
The researchers were primarily interested in changes in the volunteers’ body mass, particularly the number of new obesity cases characterized by a body mass index (BMI) of 30 or higher. All study participants gained weight, regardless of whether they had previously taken antidepressants. However, those who had used them for a long time gained more weight.
On average, those who had never taken these medications gained 0.8 percent of their body weight. Those who stopped taking them gained 2.2 percent, while those who started taking them gained 2.5 percent. Meanwhile, those who had been on these medications for a long time gained 1.7 percent of their weight, which is twice as much as those who had never taken them, reported the Daily Mail.
Dr. Camille Lassalle, a researcher at the Del Mar Hospital Research Institute, stated, “All individuals who took antidepressants had a high likelihood of gaining weight and developing obesity. However, this risk is higher for those who take these medications continuously.”
Experts are not entirely sure why antidepressants lead to weight gain, but they emphasize that serotonin is the connecting factor. Most antidepressants alter serotonin levels in the brain, regulating mood and emotions.
SSRIs block the reabsorption of serotonin, allowing more of the “feel-good” chemical to remain in the brain. This neurotransmitter, which regulates mood and anxiety levels, also acts as a traffic light for hunger, scientists noted.
After the initial intake of SSRIs, serotonin levels in the brain rise, reducing impulsivity and enhancing feelings of fullness, leading the person taking the medication to eat less. However, after about a year of taking the medication, the brain begins to adapt, suppressing the receptors that serotonin binds to, creating what is known as resistance to it. This causes the body to crave quick energy in the form of carbohydrates or sweets, which temporarily boost serotonin levels but ultimately lead to weight gain over time.
However, doctors warn against abruptly stopping antidepressants without consulting a physician. Typically, they will taper off the medication gradually over several weeks. This process is crucial because the symptoms of sudden withdrawal can be severe, including dizziness, mood swings, sleep problems, and “brain zaps,” which feel like electric shocks passing through the head.
The study’s findings were published in the journal Frontiers in Psychiatry.
