Despite a common belief that medications treating mental illnesses are connected to weight gain, new data shows an individual in a weight management program will lose weight whether or not they are taking antidepressants or antipsychotics.
Sean Wharton, MD
New research shows that individuals taking antidepressants and/or antipsychotics in weight management programs will lose weight regardless of their medication use.
A team led by Sean Wharton, MD, the Medical Director of the Wharton Medical Clinic, analyzed 17,519 adults enrolled in a lifestyle weight loss intervention at the Wharton Medical Clinic in Ontario using a sex-stratified multivariable linear regression analysis to discover the association of taking antidepressants and/or antipsychotics with weight loss when adjusting for age, initial weight, and treatment time.
The participants referred to the weight management program needed to have a body mass index (BMI) ≥ 27 kg/m2 with at least 1 weight-related comorbidity or a BMI ≥ 30 kg/m2. The individuals with a BMI ≥ 25 kg/m2, attended a diabetes management clinic, as well as a weight management program.
Each participant was required to attend at least 3 follow-up appointments with weight and blood pressure measurements. A ≥ 250‐kcal/d calorie deficit was prescribed at the second follow-up, based on their predicted resting metabolomics rate using the Mifflin-St. Jeor equation.
Using electronic medical records, the investigators extracted data on age, sex, initial BMI, initial and follow-up weight, treatment time, and psychiatric medication use.
They then grouped the participants between those taking only antidepressants, taking only antipsychotics, taking both classes of psychiatric medication or not taking any psychiatric medications.
Patients were also categorized as being overweight (25.0‐29.9), having class I obesity (30.0‐34.9), class II obesity (35.0‐39.9), or class III obesity (≥ 40), according to their initial BMI.
About 77% of patients in the study did not report taking any of the medications, while 84.4% of the 4094 patients taking at least 1 type of medication took only antidepressants, 4.2% took only antipsychotics, and 11.4% took both.
Regardless of psychiatric medication use, the investigators found that patients lost a significant amount of weight (P > .05) and women taking psychiatric medications lost a similar amount of weight as women who were not taking psychiatric medications (P > .05).
The team also found that men taking antidepressants lost slightly less weight than men taking both types of medications or neither class of psychiatric medication (3.2 ± .3 kg vs. 5.6 ± .9 kg and 4.3 ± .1 kg; P <  .05).
“Consistent with these findings, our study observed significant reductions in weight for all patients regardless of whether they were taking psychiatric medications,” the authors wrote. “This may suggest that weight management interventions may be as equally beneficial in populations taking psychiatric medications as in those who are not.”
According to a 2006 study, individuals with mental health disorders have up to 1.5-times greater odds of being obese, with several antidepressants and the majority of antipsychotics associated with significant weight gain.
However, the symptoms of mental health disorders often impede an individual’s ability to lose weight for a bevy of reasons, including increased appetite and sleep dysregulation.
It is unknown whether these factors represent additional barriers for individuals with mental illnesses trying to lose weight.
“Thus, the objective of this study was to compare weight loss outcomes of patients taking antidepressants and antipsychotics (or both) with those of patients not taking any psychiatric medications in a physician‐led lifestyle weight management program,” the authors wrote.
The team said further studies are needed to corroborate some of the findings, including the sex differences in the effect of psychiatric medication on weight loss.
The study, “Effectiveness of a Community‐Based Weight Management Program for Patients Taking Antidepressants and/or Antipsychotics,” was published online in Obesity.