Consider fitness. What makes a person fit. An early question that should be asked is what the environment demands, because fitness implies that one "fits" into a specific environment. Someone who is fit for polar regions will not resemble someone who is fit for equatorial regions. Most of the queues we pick up on as attractive can be linked back to our fitness, and the attributes that made us fit in a natural setting. I guess it's no surprise that there are people out there that are attracted to people that best resemble potatoes. They are fit to the environment of their sofa.
And always, when in doubt, titties.