I was looking forward to this dress because the lines look like an optical illusion but it's the type of material that clings to every curve/bulge.  I am petite and weigh 115lbs.  I bought a small and it fits well in the top half of the dress but it HUGS my pouch. My stomach is not large but I do not want to emphasize the 'pouchiness' of that area.  Based on the way the dress fit, I believe a medium would be too loose in the top part of the dress.  The dress looked ridiculous hugging my curves in that way.