It's a little surprising that Mario hasn't done away with his big-boned physique after all these years of strenuous athletics, but even Luigi has to admit that his brother needs to hit the gym as hard as he's been hitting the cakes Peach bakes him every week.
That's where an underground team of government scientists steps in. By using science to turn Mario into a buff freak with a rage complex and the reflexes of a caffeinated ninja cat, they'll have created the perfect super soldier. The only question is: whose side will he be on in the coming war between man and cyborg? That will probably depend on who can bake a better cake, to be honest.