Our 3E games never went past about 14th because they get so "unrealistic" if you're trying to play "lower magic"
I'm thinking 4e would be the same.
jh
The recipe for playing a "gritty" campaign (which is what I understand from your "realistic" comment) is:
1- The only race open to PCs is human... the other races are either monsters, or strange fey folk with alien motivations and intentions.
2- The only power source open to PCs is martial. Divine magic either doesn't exist or is very limited in scope, and Arcane magic is always evil.
The advantage of 4th edition here is that you can play a well-balanced party using only the martial power source.
3- Use Keterys' system of staggered additional bonuses to avoid awarding magic items to PCs.
4- Optionally, you could stick to playing on the Heroic and Paragon tiers. The reason why the tiers are explicitly named and separated is because WotC recognizes the fact that the game changes in focus a low, mid and high levels, and recognizes that some people like playing in some stages better than others. Me? I'd enjoy playing heroic tier games for years on end, but that's just me...
And... that's it basically. The beauty of this is that, with these simple steps you have turned D&D into a Sword&Sorcery, GreyMouser/Conan style game.
In previous editions doing this was much more complicated (and the best approach was to use a different set of rules, like Mongoose's Conan RPG or Iron Heroes). In 4th edition this style of playing is available [almost] out of the box.