Serotonin connection to weight loss

Question
If antidepressants increase levels of Serotonin, and increased levels of serotonin create feelings of fullness; why do most people gain weight or have trouble losing weight while taking antidepressants?

Answer
Hello Amy,
Great question.  And I do have a theory for you.  However, it has not yet been confirmed in enough studies to say it is a fact.  But I will share it with you anyway.  

You are quite accurate that The SSRI medications prescribed for depression (and anxiety, and PMS) elevate the circulating Serotonin levels in the blood.  they do so by blocking receptor sites that would normally take the Serotonin out of the blood stream.  I have had hundreds of people come to me for weight reduction while on an SSRI medication.  I have also had people begin taking an SSRI medication while on my weight loss program.  I see the same thing each time. So here is my theory.

The increase of Serotonin in the blood stream causes a change in the way that carbohydrates are metabolized.  Now, carbohydrates are a precursor to Serotonin.  So eating carbs can increase the manufacture of Serotonin. With both carbs and an SSRI medication, the carbs are more easily stored as fat.  I have seen this to be especially true for Paxil.  

Before I had so many experiences with this I believed that the people who took the medication were just becoming more happy and as a result had an increased appetite for life, and also for food.  They then were getting out of their house more, going to eat with friends, etc.  And this was causing the weight gain.  However, my experience with patients has shown me there is a carbohydrate - SSRI medication connection.

The solution that I have found to be most effective has been to have the weight loss individual utilize a carbohydrate controlled diet.  What has been most effective is a ratio of 40% carbs, 40% protein, and 20% fat.  In addition, exercise really seems to accelerate weight loss in these people.  More often than not, people who begin eating this way find that they are able to eventually taper off and discontinue their medication.

I would recommend anyone who is taking an SSRI and having difficulty losing weight try this macronutrient ratio.  Record their food for a week and see if when they level carb intake to equal protein intake they lose weight.

I have utilized this approach so many times now with patients, that I have a number of psychiatrists that refer patients to me so that I can teach them this way of eating.

I hope that I have been helpful in my explanation, and please do not hesitate to follow up with any additional questions, especially if you are wondering about the diet specifics that I utilize.  It is possible to take an antidepressant and still lose weight, just as long as the person is willing to make some dietary changes.

Best of health,
Dr. Bret  

1. Prev:Gradually Decreasing Weight
2. Next:Taking wheat out of my kids diet