The important thing is that while heroin and cocaine and tobacco and every drug and junk food cause dopamine release, there are healthier ways that you can put this into your life. And the three big ones are intimacy ... physical activity ... and the third thing is music.

I thought - being a musician doesn't help your medical credibility really. Although I started to rethink that when I learned that Albert Einstein was quite a violinist and in fact would perform a lot with symphonies. So if it's good enough for Albert, it's good enough for me.

Chimpanzees will eat a little bit of meat. But, they never eat dairy products, and no other animal would do that.

I'm thinking of people in rural Japan and China, where McDonald's hasn't yet arrived. These are the thinnest, healthiest, longest-lived people with the least risk of cardiovascular disease and diabetes.

In my own life, I decided to leave meat off my plate in medical school, but was a bit slow to realise that dairy products and eggs are not health foods either.

The thinnest people on the planet are those who eat the most carbohydrates.

Overall, our population is in the worst shape it's ever been. Children are in terrible shape. We have absolutely unprecedented numbers of obese and overweight children - one in three now. A generation ago it was something like one in ten.