"John Hay (1838 - 1905), one Lincoln's private secretaries, wrote out some of his recollections of Lincoln's daily personal and official habits as President. Hay was in Paris serving as Secretary of United States Legation when he wrote the letter, about a year and a half after Lincoln's death".
"He was very abstemious, ate less than anyone I know. Drank nothing but water, not from principle, but because he did not like wine or spirits."
The conduct of the war contributed mightily to Lincoln's rapidly aging appearance. Look at this photo-essay examining his facial decay year by hear: click here.