"I love chocolate and ice cream, and I have those things once in a while. It's good to indulge cravings and your tastes once in a while...as long as you balance those things with healthy foods." Sometimes, she'll opt for a piece of dark chocolate for a snack or a glass of Diet Coke.

With Twitter as his Excalibur, the president takes on his doubters, powered by long spells of cable news and a dozen Diet Cokes. But if Mr. Trump has yet to bend the presidency to his will, he is at least wrestling it to a draw. Watching cable, he shares thoughts with anyone in the room, even the household staff he summons via a button for lunch or for one of the dozen Diet Cokes he consumes each day.