Medications Causing Weight Gain/Loss?

gbel1975

I have a general question that comes from a number of threads I've read here on MFP.

Many people state that a medication has caused them to gain weight. You can substitute whatever medication you want for the purposes of this question...Birth control, acne, thyroid, BP, etc., etc., etc.

I'm curious, and hope someone can post a scientifically-based response, how is it that a medication causes weight gain? I mean if calories eaten = calories burned, you should maintain your weight. If calories eaten < calories burned you should lose weight. What is it about a medicine that could cause weight gain and affect the above equations?

Two ideas that might come to mind are 1> the medication slows down one's metabolism and/or 2> the medication causes one to have a higher appetite. I know I've experienced #2 when I've been on anti-inflammatory steroids like prednisone for allergic reactions. However I wouldn't say the medicine CAUSED weight gain. My succumbing to my elevated appetite, on top of being sick and less active, are what caused the weight gain.

Thoughts?