I kind like this definition from Urban Dictionary as it is the most accurate description for me:
noun. When someone is intimidated to go to the gym (or use gym equipment) because the muscleheads are constantly using the weight machines/free weights.
Back in July, my work held a gala. I decided weeks before that I was going to wear my graduation dress to the gala, and the night before I tried it on just to get a feel for how it would look. It didn’t fit – and keep in mind, I only graduated one year ago. I was aware that I had put on some lbs after starting work full time, but not aware that I had put on that much. Daily (oily) sausage omelettes, uncontrollable snacking, and sparse gym sessions are essentially what led me to being the heaviest I’ve ever been. And not just heavy – but generally sluggish with a complete lack of energy.