I'm not sure about what the phrase "a healthy economy in a healthy body" would mean.
However the main sense of "oeconomia" was "household management". The current sense of "resources and wealth of a country" is from the 1650s.
This means that someone is both physically well, and what they busy themselves with is also well and commendable: "healthy body, healthy occupations". I'd like the OP to explain what they want to say exactly, and why they want to say it (eg is this a tattoo request).