Actually, it's the other way around; having your saddle too far forward requires more of your weight be supported by your arms and causes you to slide even further forward.

When you lean forward while standing, you move your bottom back to maintain balance. Try this with your heals against a wall if you don't believe me.

On a bike, you need your saddle behind the BB for balance or your arms end up supporting your upper body instead of your back.

OTOH, it sounds like you may have other issues to deal with.

Read this article: http://www.peterwhitecycles.com/fitting.htm

-murray