Hi Emma,
Duromine helps lose fat by suppressing your appetite, meaning you don't feel as hungry as usual, hence you eat less than usual. The pills do not burn fat tissue or the fat cells, i.e. it cannot build new fat cells either. You can read more about the effect of
Duromine here. It is true that you can gain weight after ANY diet, but it depends on the lifestyle only. I always say that if you want to maintain your weight loss result once you finished Duromine therapy, or any other successful diet, you gotta be careful and keep tracking what you eat and your physical activity for life. Well, I am sure you already know this
So, IMO your coworker gave you quite questionable information and there's nothing to worry about at this point.