Do anti-deprssants cause weight fluctuations?

Not fluctuation. Weight gain is a possible side effect of nearly all antidepressants. However, each person responds to an antidepressant differently. I have had patients who have lost weight on certain antidepressants, such as wellbutrin (bupropion). However, weight fluctuation, where weight goes up and down, is not typically seen. Consider lifestyle and diet as more probable causes, but bring this up to your prescribing md.