Sara Mahoney full of Baloney.
Every runner knows you cannot run when eating junk.
3 factors: rest, quality food and running.
Running exercises the heart, lung and blood.
That’s what Jim Fixx missed. He did not change his fuel mix, instead he continued the same junk diet. Still, running bought him several additional years, considering that genetically the deck was not stacked in his favor, since other males in his family died at younger ages.
That all said, as a cyclist competing in masters events, I have found that it is not so much how much fuel you take in, it’s also the quality of the fuel that matters as well. I had worked with a sports nutritionist a number of years ago, dropped a good amount of weight, but even more so, had a huge drop in percent body fat. No change in the quantity, no real change in training, except maybe in the volume I was able to handle since I was recovering better. And no, I was not using the “juice”, since I was potentially subject to testing by USADA. The big change was the fuel mix.