Once upon a time I got injured three days before my 21st birthday, and discovery of Imperial IPAs. Come the end of the semester I stepped on a scale and thought the dang thing was broken.
At first I was horrified at the realization of my fat face, and chafing thighs, but then I was somewhat pissed at my girlfriend for not telling me to quit being such a fat ass. She said something about loving how she could hear me thundering toward her 10 minutes before I entered a room. . . .
Anyway, I feel it's less about your desire to be nice and sugarcoat the truth, so much as to play your role in both communicating what you see, and supporting his health.
(Although, that's easier for me to demand someone else do for me, than actually tell someone myself. . . .)