I had surgery almost 8 years ago, I'm now 35. It was brought on then by steroid use(a little but none the less, lesson learnt). However I haven't touched any ever since & aren't on any medication. The only supplement i take is an over the counter pre-workout. I noticed it started up slowly in my right nipple(the dr said he had left a little behind for contouring) about 2 years ago & nothing in the left up until now, literally in the last 2 months the left is almost the same size as the right, just out of nowhere. The only thing I can think of that may have brought this on is I have picked up about 20lb over the last year or so. Can't understand why this is?

Linkback: https://www.gynecomastia.org/smf/index.php?topic=31649.0

My guess is that it is related to your weight gain. Otherwise you need a more thorough history and exam.

Just catching up on a few older posts--Depending on what pre-workout items you're using, I have noticed in the past couple of years an increase in the number of cases I've treated related to "pro-hormones" and other testosterone boosters and pre-workout products as compared to regular steroids.  The pro-hormones and other testosterone boosters are getting "better" in terms of altering hormone levels, but with that comes increased risk of side effects, including gynecomastia.  I caution all of my patients about supplements, since products that contain "proprietary blends" of items might include hormonally active agents that are not otherwise detailed in the contents. This can provide a gynecomastia surprise!
Alternatively, and probably more commonly, a factor in "recurrent" gynecomastia is related to weight gain.