The whole idea of Feruchemy reminds me a bit of how some people actually try to adjust their body composition with different strategies for fitness or even sports. I remember hearing about people who use things like Steroids Canada to build muscle or cut fat, depending on their goals. But in this case, steroids can actually help.
I think the idea of changing things like hydration or adding a bit of bulk to make yourself look different could be useful in the fitness world too.