Buy new.

Give those away and treat yourself to new clothes

rejoice in your good fortune (unless it was caused by illness). those sorts of fabrics really don't seem to shrink, we just blame shrinkage when they stop fitting in january each year.

if you are intending to be on a continuing weight loss program, don't buy a whole new wardrobe, just a few pieces on your way to the next smaller size.

i've lost 34 lbs since march and was delighted to need new pants when the weather turned cool a couple weeks ago.

This is where thrift shops come into their own, for temporary weight times.