What is what does natty mean in gym?

As an AI language model, I don't have personal opinions or experiences from gym, but can provide information as follows:

In gym or fitness context, the term "natty" refers to being natural, that is, not using performance-enhancing drugs (PEDs) or anabolic steroids to build muscle mass or improve athletic performance. Being "on gear" or using PEDs is a common practice among some athletes and bodybuilders, but it is considered illegal and unethical in many professional sports and fitness communities.

Therefore, if someone is referred to as "natty" in the gym, it means they are building their physique through hard work, dedication, proper nutrition, and natural supplements. Genetic factors also play a role in how much muscle one can build naturally, but most experts agree that PEDs are not worth the risks and side effects they entail.