What percentage of patients gain about 20% body weight on antipsychotics?

• A. 50% of patients gain 20% (primarily adipose)
• B. 10%
• C. 70%
• D. 25%

Answer: (A)

Weight gain from antipsychotics, especially the second-generation ones like olanzapine and clozapine, is a common and meaningful side effect. The most typical pattern is that about half of patients will accumulate around 20% of their body weight over several months of treatment. That level of gain is primarily fat (adipose tissue), which helps explain why it carries a higher risk for metabolic problems such as insulin resistance, diabetes, and dyslipidemia. Because this risk is real and fairly common, clinicians routinely monitor weight and metabolic parameters and may consider switching to agents with lower weight gain risk or adding lifestyle and metformin-focused strategies to mitigate the impact.