Many fonts come with several variants that can be accessed from most OS X applications. Here's an example showing several variants of the Latin Modern Roman font.
(These variants in the screenshot are all displayed at 11 pt size, but their shapes/weights are designed to be used at the indicated sizes; hence the names "10 Regular", etc.)
You don't have to install a special font to try this though. Many fonts that come with the OS, such as Helvetica Neue on OS X, have them.
Using Format -> Show Fonts in Mathematica brings up a window where these variants can be chosen. But choosing them has no effect.
Question: Is it at all possible to use these variants in Mathematica 10.3?
I am primarily interested in OS X, but answers for other operating systems are welcome too.