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Antidepressants and weight gain
Dear Doctor
I have been on a particular antidepressant (Mirtazapine) for a year and it has worked reasonably well. It is better than any other that I have tried anyway. However, since I have been on the antidepressant, I have put on more than 3 stone and have gone from being a healthy weight to overweight. I haven’t changed my diet much, although I do have a slightly larger appetite now I am on the drug. Other people I know have also put on weight on Mirtazapine. My waistline is now over the healthy limit for risk of heart disease and diabetes that was in the news recently. I also hate being this fat and feel it is affecting my confidence and my mood.
My question is, when do physical health concerns outweigh the benefits of an antidepressant and is weight gain a good reason to come off a drug? I have tried quite a few antidepressants before this and none of them have worked as well as Mirtazapine. I’d appreciate your opinion on this.
Joanna
Dear Joanna
Thank you for raising an important issue that concerns many people on antidepressant medication.
Clearly, mood and appetite are closely intertwined. Expressions such as ‘worried sick’ and ‘eating for comfort’ are used in everyday conversation. An alteration in appetite is, in fact, one of the diagnostic features of a depressive illness.
So, it is not surprising that drugs which affect mood, such as antidepressants, may also affect appetite. Indeed, all antidepressants have the potential to affect appetite and the effect will more commonly be an increase rather than a decrease.
However, it is important to emphasise that even though antidepressants may increase appetite this does not mean that they will automatically cause an increase in weight. The normal approaches to diet and weight control are still applicable, though it can, of course, be desperately difficult to control appetite and weight when the mood is low with depression. It is also worth mentioning that weight can be controlled by increased calorie expenditure, through exercise, as well as by reduced calorie intake through diet. This is particularly relevant in depression since exercise can also have a most beneficial effect on mood.
Generally, the older antidepressants, particularly the ‘Tricyclics’, are more inclined to cause increased appetite than the newer ones, such as the ‘SSRIs’. Of the SSRIs, Fluoxetine (‘Prozac’) seems the least likely to increase appetite. Unfortunately, Mirtazapine, although a newer antidepressant, is often associated with weight gain.
In your case, there are multiple factors to consider: the adverse effect on your self-esteem and mood through having gained 3 stone in weight; the risks to your physical health associated with this substantial weight gain; the fact that Mirtazapine has improved your mood more effectively than the antidepressants you have been on previously; the possibility that a change in treatment may destabilise your mood; and, finally, the possible difficulty of identifying an alternative antidepressant that will help your mood and also make it easier for you to shed some of your unwanted pounds.
Trying to weigh up the risks associated with these various factors is far from easy. Depression can be an extremely severe and debilitating illness and I would generally tend to be more concerned about a current risk of severe depression than about possible longer term adverse effects from being overweight. However, even this very general advice must be tempered by the knowledge that being overweight can itself have a most adverse effect on mood.
Clearly, this is a very difficult question that should be discussed at some length with a doctor who is familiar with the detail of your previous history of depression and the treatments you have received. In the first instance, this could be your GP, who should also be able to suggest forms of advice and support regarding diet and exercise. I would also expect your GP to want to exclude other reasons for your weight gain, in particular under-activity of your thyroid gland. It may well be appropriate for your GP to arrange for you to receive specialist advice from a consultant psychiatrist.
Without being familiar with the details of your past history of depression, I cannot speak with confidence. However, I would be surprised if, having weighed up the pros and cons, any specialist you see does not advise a change of antidepressant.
Yours sincerely,
Gerry McPartlin