Pretty soon the boxer will pass on the burger. He will deny the cheese. He will skip the sushi that he adores, and he will not—as Sylvester Stallone did so memorably and nauseatingly in "Rocky"—break five eggs into a glass, and slurp them down raw.

Instead, the boxer will embrace the quinoa. He will thrill to the avocado and befriend the almond. He will enjoy the spinach, the tofu, and the $7.95 organic smoothie that bears his not-yet-household name.

And...