We know that people with mental health conditions are at a higher risk of having obesity, and that people with obesity are at higher risk of having mental health issues. We also know that many medications used to treat mental health conditions cause weight gain, including many antidepressants and antipsychotic medications. Does taking medication for mental health issues put people at a disadvantage for weight loss?

This question was addressed in a recent study, published in the journal Obesity by Wharton and colleagues. They reviewed data from over 17,000 patients enrolled in a health behaviour change (lifestyle) program at the Wharton Medical Clinics in Ontario. They looked at antidepressant use, antipsychotic use, and whether use of these medications had an impact on success with the lifestyle program.

They found that over 23% of people enrolled at the clinic were taking at least one psychiatric medication (this compares to about 7% of the general Canadian population taking these medications). They found that people overall lost a similar amount of weight, regardless of whether or not they were taking psychiatric medications (the average weight loss was about 2.9%, consistent with the typical 3% weight loss seen from long term lifestyle interventions). People taking psychiatric medications associated with weight gain lost a similar amount of weight as those taking psychiatric meds that are weight neutral or associated with weight loss.

Interestingly, while women lost the same amount of weight regardless of whether or not they were taking psychiatric meds, and regardless of what type of psychiatric medication they were taking, the detailed story was not as straightforward for men. In men, they found that men taking antidepressants lost a little less weight (3.2kg) compared to men taking both antidepressants and antipsychotics (5.6kg) and compared to men taking no psychiatric medications (4.3kg).

These findings underscore how common mental health issues (and need for medications) are in people who struggle with weight, with over 3 times more people attending this weight management clinic needing medication for mental health issues, compared to the general population. These results also bring good news, that people participating in a weight management program can lose weight regardless of psychiatric medication use. While the overall data suggest that it didn’t seem to matter much whether people were taking mental health meds known to be associated with weight gain or weight loss, we do encourage selection of medications associated with weight loss where possible (read here for a list of medications associated with weight gain, and alternatives that are weight neutral or associated with weight loss).


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