The best thing about formal suits is that you will never look fat in them even though you wear the fitted ones. (outfittrends.com)
Even today, I change clothes 27 times so that I don't look fat or colors match properly. (crazyforcrust.com)
Even if you think that these bottoms look fat on you, then you can add elegant tunic / long sweater or top over them, so you can hide your problem areas. (fashiongum.com)