A recent study led by the Hospital del Mar Research Institute and published by Frontiers in Psychiatry demonstrates the link between antidepressants and weight gain.Using follow-up data from participants in the REGICOR study (Registre Gironí del Cor), researchers quantified an average 2% increase in body weight among individuals undergoing this type of treatment. The study involved researchers from the CIBER for Pathophysiology of Obesity and Nutrition (CIBEROBN) and the CIBER for Cardiovascular Diseases (CIBERCV), as well as from Ramon Llull University, the University of Vic-Central University of Catalonia, University College London in the UK, IDIAP Jordi Gol, and the Girona Biomedical Research Institute Dr. Josep Trueta (IdIBGi). This is the first study of its kind conducted in Spain.

The study followed 3,127 adults over six years, including 1,700 women, with an average age of 55. Among the participants, 16.4% reported taking antidepressants, either consistently throughout the study period (5.1%), starting them during the study (6.2%), or taking them at the beginning but later discontinuing them (5.1%). Over the six-year follow-up, all participants gained weight (an average increase of half a kilogram), but the weight gain was more pronounced among those on antidepressant treatment.“All individuals taking antidepressants had a higher likelihood of gaining weight and developing obesity. This risk is even greater for those who use these medications continuously,” explains Dr. Camille Lassale, a researcher at the Hospital del Mar Research Institute and the Barcelona Institute for Global Health (ISGlobal), a center supported by the la Caixa Foundation.

2% Weight Gain

The study considered the well-known bidirectional relationship between depression and obesity, as well as other associated factors, such as poor adherence to healthy diets and lack of physical exercise. However, the link between antidepressant use and weight gain remained independent of age, sex, socioeconomic status, lifestyle, and the presence (or absence) of depressive symptoms. Participants who took antidepressants at the beginning and later stopped experienced an additional 1.8% weight gain compared to those who never took them. Those who started antidepressants during the follow-up and those who continued taking them throughout the study gained 2% more weight. In the latter group, the risk of developing obesity doubled. Participants who used antidepressants continuously were more frequently women, older adults, and individuals with a less healthy lifestyle (diet and physical activity).

Gabriela Lugon, a researcher at Hospital del Mar and a resident physician in the Preventive Medicine and Public Health Teaching Unit at Hospital del Mar, Pompeu Fabra University, and the Barcelona Public Health Agency, highlights that these findings underscore the need to consider this association when prescribing antidepressants and to monitor weight changes accordingly.“We cannot simply prescribe antidepressants for their positive effects without also considering this side effect,” Lugon states. For this reason, the authors of the study stress the importance of monitoring weight changes in individuals undergoing antidepressant treatment, along with other cardiometabolic health markers.

Dr. Víctor Pérez, head of the Psychiatry Department at Hospital del Mar, emphasizes that antidepressants are highly effective for treating some of the most common mental illnesses. However, “their effect on weight is not universal, although certain medications, such as mirtazapine and paroxetine, can cause significant weight gain.”He also warns that “due to the risk of patients discontinuing treatment because of weight gain, we must consider alternative therapeutic strategies to complement pharmacological treatment.”

Depression affects 280 million people worldwide and is the most prevalent mental disorder, impacting women twice as often as men. Weight gain is one of the main reasons why people discontinue treatment. At the same time, 650 million people worldwide suffer from obesity, highlighting the strong bidirectional relationship between these two conditions. Spain, along with Sweden and Portugal, has the highest antidepressant consumption rates in Europe.

Reference Article

Lassale C, Lugon G, Hernáez Á, Frank P, Marrugat J, Ramos R, Garre-Olmo J, Elosua R. Trajectories of antidepressant use and 6-year change in body weight: a prospective population-based cohort study. Front Psychiatry. 2024 Dec 24;15:1464898. doi: 10.3389/fpsyt.2024.1464898. PMID: 39777198; PMCID: PMC11703859.