In the last year, my FI has gone from a completely sedentary lifestyle to being completely obsessed with mountain biking. I'm so proud of him and his accomplishments! However, he is clueless about nutrition. He openly admits he very much prefers all things processed. (I had to recently explain what "processed" meant.) And he is not interested in eating healthier just because it is healthier for you.
He mentioned after today's trail, "Man, that was really tough. I don't know why it was so hard! Do you think it could be because of all the junk I've been eating in the last couple of days?" He's finally starting to make the connection.
However, I think something like Tosca Reno's books won't motivate him. I think a book on "here's how it will improve your athletic performance" will. Any recs?