Do Antidepressants Cause Weight Gain?
Fear of weight gain is cited as a
common reason for avoiding antidepressant medications, and there are claims all over the internet about how harmful these medications are for your brain and body. Therefore, it's worth our while digging into the evidence to understand how these drugs impact body weight!
Firstly, it's always worth beginning such an exploration by asking "how could a medication like this cause weight gain?". Some potential mechanisms you might come up with could be:
- Reducing the brain's responsiveness to signals of fullness
- Compromising the normal bodily sensation of fullness (e.g. stomach distension)
- Impacting the appetite regulation centres in the brain
- Impacting the reward centres in the brain
- Reducing exercise or non-exercise activity thermogenesis
- Simply improving depression
and associated appetite suppression
There are more potential mechanisms, but the key point to note is that there are many different avenues through which a medication could promote changes in bodyweight. For that reason, outcome evidence is really important, as we otherwise simply get lost in the weeds of mechanistic
speculation.
Antidepressants are not a single class of drugs, and there are many different drug classes under this umbrella, including selective serotonin reuptake
inhibitors (SSRIs), monoamine oxidase inhibitors (MAO inhibitors), tricyclic antidepressants (TCAs), and more. Given that different drug classes have different mechanisms of action, you may wonder if they each impact bodyweight differently. And you'd be right!
MAO Inhibitors (phenelzine, isocarboxazid, etc.): more likely to contribute to weight gain
TCAs (amitriptyline, nortriptyline, imipramine, etc.): more likely to
contribute to weight gain
SSRIs (sertraline, fluoxetine, citalopram etc.): no impact on weight, sometimes contribute to weight loss
SNRIs
(venlafaxine, duloxetine, etc.): no impact on weight
Mirtazapine: more likely to contribute to weight gain
Bupropion: likely to contribute to weight
loss
