There isn't much you can do unless you put a vinyl skin along the wrist/edge area and use a hardshell case. When you're sweating it would be a good idea to clean it as moisture and body oil/salt will slowly wear down/corrode metal. Apple's notebooks aren't the only one, HP wraps/stamps aluminum around plastic shells of several models and their notebooks developed corrosion from ownership too.
Its all about anything interacting with a persons body PH, it can be genetics of a more acidic sweat, medications, diet, salt intake, etc. For example if you eat tomato sauce and certain combos of curry an average persons' body will have a PH spike ~3-6 hrs... if you want to lower the acidic levels, add sliced/chopped carrots or potato in pasta sauce & curry dishes.
As far as my Macs, owned two PowerBook G4s without any corrosion spots and the only damage I ever got was in my mid-undergrad life of a light scratch on my 12" PB. My 2010 13" MBP still looks great for its age, no corrosion or scratches but I put a Speck case onto it to avoid losing the bottom feet--my 12" PB G4 lost two feet, thankfully back then Apple replaced them at no cost but unibody Macs it requires a new bottom case.