I ain't gonna lie, I stay on my wife about her weight. Occasional subtle reminders go a long way. She knows better to ask me if she is gaining wait, I always say yes even if its not true. Sometimes at night I will start pinching her stomach as we are going to sleep. She is like I know, I know. Next morning she is downstairs in the gym working out.
She has a pretty active job so she's not sitting on her butt all day long which helps her keep her weight down where it needs to be. You got to stay on top of your woman, don't let her get lazy. Take her for walks and find activities that require her to move around and encourage fitness.