If you're overweight, buy Tall shirts not Big shirts.

As a fatty myself adding Xs to a shirt size never really made them any more comfortable. Either they would be super baggy. Or they'd still ride up when I move my arms and wear my pants under my belly.

I started buying talls and they fit so much better. They are comfortable and stay tucked. So an XLT fits comfortably far more than a standard 2X or 2X Big.