Chastity Keeper's Weight Reduction Plans

Hi everyone… I’m looking for some suggestions to mix things up in the weight loss ‘game’. I noticed another thread here that touched on this idea, and it seemed like a good chance to gather your thoughts. At present, I get locked away for about two weeks every couple of months. I’d prefer more frequent locking, but my wife doesn’t mind much (she likes the benefits; she just has low libido anyway). She wants to shed some weight too. While I don’t really push her on it, she aims to lose a total of 3 stone. I probably make it harder for myself since I’m content with overeating and drinking most evenings… So how can we turn this into a game that helps her slim down while keeping me caged? The key is finding a way where she still controls my chastity, but there’s a clear reward linked to weight loss? I imagine a weekly scoring system: Lose more than 2lbs =? Lose between 0 and 2lbs =? Gain between 1 and 2lbs =? Gain more than 2lbs =? Any thoughts? One idea I’ve had is that she wouldn’t mind having sex only once a month, or even less. So if one of the ‘forfeits’ involves her needing to have daily intercourse… Thanks!