Muscle Theory is the theory that increasing muscle mass and decreasing body fat is the easiest way to get laid for free via online dating in your immediate location. That muscle is more important than height, face, personality, or frame in attracting women, especially if the person isn't severely facially deformed or a midget. According to a study by UCLA, muscle-bound men report almost 3 times as many sexual partners as men without a muscular physique. This theory is promoted by MGTOW youtuber LFA. It is also the dominant mode of thinking on Bodybuilding.com.
William agrees with the theory and takes it a step farther. Suggesting abs is the single most important physical trait in men on online dating apps. While not as quantifiable as regular muscle theory, abs theory is hypothesized based on shirtless men with abs always getting dozens of matches on tinder during catfishing experiments.