>I think friendships, for the most part, are being kept alive by the fact that the friends don't tell each other everything they could.

Then you should go with the "silent option" outlined in >>4.
Unless your friend is, in addition to being "fat and disgusting" (your wording), also a dim-witted dullard, s/he will catch on with what you say anyways, no matter how baroquely or subtly you furnish your hints.