Even inexpensive pedals in most cases will not bend from pedaling forces no matter how much you weigh, because it is your leg pressure, not your weight, on the pedal. Even pedaling out of the saddle does not put your full weight on the pedal, as the bike will rock from side to side, tires will absorb some of the stress, etc.

What WILL bend the pedal, and potentially stress the crank arms and bearings as well, is what I call the Roy Rogers method. Rather than reinvent the wheel I'll point you to Sheldon's page: http://sheldonbrown.com/starting.html where it discusses the wrong and right way to mount and dismount a bicycle.