Michael Mosley and the doctors are back. Giles Yeo tests the extraordinary claim that eating less can boost your memory. Alain Gregoire discovers our body's secret built-in stress-buster. Zoe Williams reveals how to spot a hidden illness that can cause stillbirth. Michael uncovers how a simple magnet can save the sight of people with glaucoma. And in a special report, Dr Javid Abdelmoneim investigates what's really in the cannabis-based health products you can buy over the counter.

Michael Mosley runs an experiment to test whether an extra hour a week in nature improves your physical and mental health. Alain Gregoire investigates a mysterious illness that can transform a child's personality overnight. Zoe Williams discovers the hidden body fat that can make us thin. Giles Yeo investigates whether trendy plant-based milks are any healthier than dairy. And Guddi Singh witnesses pioneering cancer surgery – using an intelligent knife that can detect tumours.