Short-term users of antidepressants who are stressed and consume a high-fat diet might have a higher risk of long-term weight gain, researchers from the Australian National University in Canberra, Australia, explained on Sunday at The Endocrine Society’s 95th Annual Meeting in San Francisco, California, USA.

Lead author Suhyun Lee, said:

“Our study suggests that short-term exposure to stress and antidepressants, rather than a high-calorie, high-fat diet alone, leads to long-term body weight gain, accompanied with increased bone and spleen weights.”

Hundreds of millions of antidepressant prescriptions are written every year globally. In the USA alone, prescriptions filled for antidepressants rose from 154 million in 2002 to 170 million in 2005. In 2008, more than 12 million such prescriptions were filled in Australia.

In developed and emerging nations obesity rates are rising. Two-thirds of American and Australian adults are obese/overweight today. Obesity/overweight are risk factors for a wide range of serious and chronic diseases, including heart disease, diabetes, some cancers, sleep apnea, etc.

Although antidepressants help with depressive symptoms, they are also associated with weight gain. How much weight a patient might put on varies. Some have gained 7% in bodyweight since starting on their medication.

In this study, laboratory rats went through a two-week period of repeated restraint to induce stress, with one group receiving fluoxetine, an antidepressant, and the other a placebo saline solution (the control group). Then, both groups received a high-fat diet for 295 days.

Lee and team found that the stress-induced mice on fluoxetine gained much more weight than the control animals (rats not on fluoxetine). The rats on fluoxetine also gained bone and spleen weight, compared to the controls.

Lee said:

“These findings may implicate different pathophysiological mechanisms in stress and antidepressant related obesity when compared to obesity that is solely diet-induced.”

The researchers also found that fluoxetine helped reduce symptoms of anxiety in the stress-induced rats.

In 2011, researchers from the University of Amsterdam, the Netherlands, demonstrated in a study that patients using antidepressants continuously were more overweight than intermittent or non-users.

Written by Christian Nordqvist