Probably this statement means that in simply words if you eat healthy you'll be healthy (my point of view). All the nutrients and proteins that you eat from something wil go ''into'' you and in a way become part of you, and so doe the fat and everything else that the food that you eat might contain, so for example, if you eat a mega huge mchamburger from mcdonald....i hope you don't expect to be thin and in shape...because those kind of food are called "junk food"...and if we go back to the statement, then in simply words it means that if you eat junk food you'll be junk yourself.
....this is very metaphoric
.But in my case, as i am italian....i am made of pasta and pizza
YEEAAH
