What kind of seat to buy? What do you have?

[Owlie]

The width you need won't change--it has to support your sitbones with a little wiggle room on each side. Since your sitbones are, well, bone, they don't change with weight. You may find that you sit differently on the saddle as your fitness improves, though.

The Butterfly is pretty much the same as my old saddle--they're made by the same company, just with a different cover and markings. Lots of people on here ride both of them, and love them. It didn't work for me, but that shouldn't discourage you from trying it. Just get it from somewhere with a good return policy!

[Velocivixen]

So today I have ridden a out 11 miles on my Brooks-and I totally forgot that I was supposed to be paying attention to it! That tells me that, for me, it's good. I didn't even notice anything about it.

Good luck on your search.