natty

This natty is short for natural and relates to the natural bodybuilding movement which eschews all performance-enhancing drugs, such as anabolic steroids, insulin and human growth hormones.  Rather a natural bodybuilder will rely on diet and training to produce natural anabolic hormones that increase strength and promote recovery.  

Natural bodybuilding is a bit of a mouthful so it has been shortened to natty, as in natty techniques.  You can be a natty, or you can be described as natty. What makes you a natty is a bit unclear since the rules about drugs vary from one competition to another. Apparently there are fake natties, bodybuilders who take drugs but lie about it.  This leads to a confusing situation in competitions.