To build the perfect body, it helps to have the right dimensions. Thankfully, the magic formula for those dimensions has been known for centuries. It's called the golden ratio—a dividend of two measurements that's roughly equal to 1.618-. Its influence can be seen in the shape of a seashell, the spirals of a pinecone, and the Parthenon in Athens. And in blueprints for the archetypal human form: Leonardo da Vinci's Vitruvian Man and Michelangelo's David. In fact, whether you're looking at art or nature, you'll find this ideal proportion turning up everywhere.
So it's no surprise to learn that chicks dig a physique that measures up to the golden ratio. An Archives of Sexual Behavior study reveals that women are most attracted to muscular men whose shoulders measure 1.6 times the size of their waists.
Of course, it's not always easy or practical to measure the width of your own shoulders—you need someone to do it for you. But you can use your chest circumference as a handy stand-in stat. "They're just different measures of the same thing," says Viren Swami, Ph.D., author of The Missing Arms of Venus de Milo: Reflections on the Science of Attractiveness. One of Swami's studies shows that women prefer a chest-to-waist ratio of 1.4 instead of one in which the two measures are closer to each other. (It's a smaller ratio than 1.6 since your chest is narrower than your shoulders.) The bottom line: When women look at men's torsos, the V shape is victorious.
You can figure out your own proportion in three easy steps. All you need is a tape measure and a calculator.
1. Measure your shoulder circumference at its widest point—usually around your shoulders and chest in a line halfway between your nipple and collarbone. (If you're on your own, you can measure your chest at its widest point, just below your armpits.)
2. Determine your waist circumferenceby wrapping a measuring tape around your abdomen so that the bottom of the tape touches the top of your hip bones.
3. Divide the circumference of your shoulders(or chest) by that of your waist.
You don't have to look like a cartoon superhero to hit the ideal proportion: If you use the standard from Swami's studies, you could hit the jackpot by having a 45-inch chest and a 32-inch waist.
To visualize the look, think Muscle Beach 1940, not WrestleMania 2008. (For the sake of comparison, the most popular muscleman from the presteroid era, Steve Reeves, had a 52-inch chest and a 29-inch waist—a way-beyond-golden ratio of 1.8.) Leanness rules over hugeness. What's more, lower-body dimensions don't have the same appeal as those of the top half. "This point is pretty conclusive," Swami says. "When women judge a man's physical attractiveness, lower-body shape plays a negligible role."
Which isn't to say that you should ignore your southern hemisphere, because it's exceedingly difficult to develop a lean, muscular upper body without using your body's biggest and strongest muscles: your hips and thighs. Their immense power to drive metabolism and generate muscle-building hormones will help grow your chest, shoulders, arms, and upper back, too. The trick is to use your meatiest muscles strategically to produce the eye candy women find so tasty. That, of course, is the goal of the three-exercise workout below.
But before you launch into the workout, know that you don't have to achieve picture-perfect results to get the girl. "There's some research to suggest that women aren't too keen on the most attractive men—they consider them too far out of their league," says Swami. The golden ratio is nice to shoot for, in other words, but you won't be disappointed with a silver or bronze.