According to a significant new study, millions of Americans using a popular medication may be doubling their risk of obesity.
It turns out that about 10% of the U.S. population takes antidepressants for various mental health issues like anxiety and depression, hoping to find relief and improve their well-being.
But this could potentially lead to another serious health problem.
Researchers in Spain analyzed data from over 3,000 adults and discovered that those who had been on antidepressants for roughly six years tended to gain about twice as much weight compared to those who didn’t take these medications.
Interestingly, this finding held steady even when considering factors like diet, exercise, and mental health, indicating that the effects of these drugs accumulate over time.
About one in four participants in the study experienced a weight gain of more than 5%, a level that’s associated with an increased risk of conditions like diabetes, heart disease, and joint issues.
Those who began their antidepressant journey during the study gained around an extra 3% of their body weight, while individuals already on the medication at the outset saw an increase of about 2%.
Dr. Gabriela Lugón, involved in the research at the Hospital del Mar and Pompeu Fabra University, emphasized the need to weigh the pros and cons of prescribing these medications, as the side effects can’t be overlooked.
Average weight gain for the participants, with long-term antidepressant users facing higher odds of obesity.
Depression and anxiety are alarmingly common in the U.S., with around 21 million and 40 million people affected, respectively.
The most frequently prescribed antidepressants, known as selective serotonin reuptake inhibitors (SSRIs), aim to enhance mood by boosting serotonin levels—a hormone linked to feelings of well-being.
While modern antidepressants are generally more effective and come with fewer side effects than older medications, they still have drawbacks. Notably, weight gain can emerge both quickly and as a persistent issue. For many people, unwanted weight is a key reason they decide to stop treatment, creating a challenge for both patients and healthcare providers.
Dr. Víctor Pérez, leading the Psychiatry Department at Hospital del Mar, acknowledged that while these drugs are effective, weight impact can vary significantly among them. Some, like mirtazapine and paroxetine, are particularly associated with substantial weight gain.
The study, initiated in 2005, involved 6,352 adults aged 35 to 79 from northeastern Spain and followed them over six years. Participants were sorted into four categories based on their antidepressant usage: never users, new users who began during the study, those who quit by the follow-up, and long-term users who continued throughout.
Data on their weight, height, diet (based on the Mediterranean diet), exercise, depression symptoms, smoking habits, diabetes status, and blood pressure were collected.
The focus was specifically on body weight changes and the emergence of new obesity cases, determined by a body mass index (BMI) of 30 or more.
Percentage of adults diagnosed with depression in their lifetime.
All participants in the study gained weight, regardless of whether they were on antidepressants or not. However, those who took the medications gained more. On average, individuals who never used antidepressants saw a weight gain of 0.8%, while those who stopped using them gained around 2.2%. New users added about 2.5%, and long-term users gained 1.7%.
This essentially means that those on antidepressants gained at least double the weight compared to non-users.
Dr. Camille Lassale, a researcher at the Hospital del Mar Research Institute, pointed out that all individuals taking antidepressants faced a higher risk of weight gain and obesity, a risk exacerbated for those on long-term regimens.
While the mechanism behind why these medications lead to weight gain isn’t entirely clear, serotonin is a key player. Most antidepressants, including Prozac, Zoloft, Effexor, and Cymbalta, modify serotonin levels to help with mood regulation.
SSRIs work by preventing serotonin from being reabsorbed, allowing more of this “good mood” chemical to linger in the brain. In contrast, serotonin-norepinephrine reuptake inhibitors also impede norepinephrine reabsorption, a chemical that helps regulate energy.
Serotonin not only affects mood but also influences hunger. Initially, when starting an SSRI, serotonin levels increase, reducing impulsivity and promoting a feeling of fullness, which can lead to reduced food intake.
However, after about a year, the brain adjusts by downregulating the receptors for serotonin, leading to what researchers term “serotonin resistance.” This shift can trigger cravings for sweet or carb-rich foods, temporarily boosting serotonin levels but ultimately contributing to weight gain over time.
Dr. Pérez suggested the need for considering other therapeutic options alongside medication due to the weight gain risk, as this can drive patients to stop treatment.
It’s important to note that abruptly discontinuing antidepressants without professional guidance is not advisable; typically, healthcare providers taper patients off gradually over weeks to minimize withdrawal symptoms. These can range from flu-like sensations to severe mood swings and even “brain zaps,” which are jolts of electric sensation in the head.
The findings were published recently in Frontiers in Psychiatry.
