Who isn’t anxious about how health changes with age? If you’ve recently found yourself fretting over the risk of cognitive and physical decline, Mark Hyman, MD, has some crucial news. In his new book Young Forever: The Secrets to Living Your Longest, Healthiest Life, Dr. Hyman lays out his method for reversing aging and reducing the risk of later-in-life disease. And in this intimate, comprehensive chat with Katie, Dr. Hyman explains how he eats for health, which nutrient-dense foods he loves, and what types of exercise are most sustainable as we age.

Additionally, he elaborates on how you can compensate for nutrient-deficient foods with a simple foundation of supplements: “I think the basic minimum would be a vitamin D supplement, fish oil, and a multivitamin. Then you can get all fancy.” (And yes, he explains what he means by “fancy,” plus how you can tailor and tweak your own supplement routine.)

Katie and Dr. Hyman also delve into what intermittent fasting really means for your body. Spoiler alert: It’s not starvation. “The terminology is confusing for people, but basically, it means time-restricted eating. It’s eating dinner at six at night and then not eating until breakfast at eight in the morning,” he says.

And, as promised, Dr. Hyman explains how you can optimize your morning by noshing on fat and protein — and why your daily oatmeal isn’t as healthy as you think.