I'm curious, how big is the difference in metabolism? I've heard this before, but it would make sense that pure fat in it self does not increase your oxygen comsumption that much, especially at rest or minimal movement (diving). Of course it makes a difference when moving around.
But does it actually affect, say, static performance? How big is the difference?
Just asking, no reason
To the original question, without knowing what your definition of over weight is, it's hard to say. But if you're talking about some extra insulation while being reasonably fit, I'd say it's propably more of an advantage, especially if you train in cold conditions. If we're talking about BMI over 30 I'd say I have no idea, but if you have no other apparent health condition preventing you from diving, as Eric said, I see no reason you couldn't excel.
