It's an engaging and entertaining book and highly recommended.
Many remarkable characters are featured in the book and among them are two marathoners:
Scott Jurek (42) and Dr. Ruth Heidrich (78). Each has his/her own stories,
"Eat and Run" from Jurek and "Lifelong Running" from Heidrich.
Read about their life struggles and pay attention to their diets. Be well.
P.S. I understand many people struggle with English. I don't have the time to translate.
Take this as an opportunity to discover a world.