The x-back is actually CONCAVE, opposite a chair that supports the lumbar region of your back, so if you want to actually support your lower back, you would have to bend your back opposite of its natural curve to do so, which of course, no one does. You could use a pillow to support your back, but that wouldn't look right with this chair. So you'll just have to sit up straight and do your abs, I guess. If I had known this before I ordered six for my dining room, I might have looked elsewhere. Still, they're nice chairs and attractive. I got the dark walnut color.