Which antidepressant is least likely to cause weight gain?

• A. Fluoxetine
• B. Sertraline
• C. Mirtazapine
• D. Venlafaxine

Answer: (B)

Weight changes with antidepressants vary by drug class and even individual. Some medications increase appetite and lead to weight gain, often due to mechanisms like histamine H1 antagonism and metabolic effects. Mirtazapine is a classic example of weight gain risk because it strongly stimulates appetite and has sedating effects that can reduce activity.

Among the options, fluoxetine stands out as the one least likely to cause weight gain. It is often weight-neutral or even associated with weight loss in many patients, likely due to its activating effect and potential appetite suppression in the early phases of treatment. Sertraline and venlafaxine are generally weight-neutral but can be associated with modest weight changes in some people over time, while mirtazapine more reliably increases weight.

So, fluoxetine is the antidepressant least likely to cause weight gain.