fitness fanatic in British English (ˈfɪtnɪs fəˈnætɪk ) noun. informal. someone who is obsessed with exercise and keeping himself or herself fit.

A person who is significantly conscious of their health. health freak. health nut. health enthusiast. fitness fanatic.

Gym Rat. Definition: Someone who spends a lot of time in the gym and makes working out their personality. Used in a Sentence: “All he does is lift weights, he's a total gym rat.”

Regular physical activity is one of the most important things you can do for your health. Being physically active can improve your brain health, help manage weight, reduce the risk of disease, strengthen bones and muscles, and improve your ability to do everyday activities.