a person described as fit can be described as healthy.
the consideration of fit individual being healthy is more related to the physical aspect as they train their bodies to to achieve a certain goal. With said goal the individual gains plenty of pros towards this accomplishment by increasing their stamina, strength and other things along that line.
Some people that are fit also achieve their results by their diet, which plays a big role in a persons health .
With this in mind a person that is decribe as fit can also be considered healthy