Is ultra-processed food causing obesity in children, and could it even be addictive? Dr Chris van Tulleken investigates as he undergoes an experiment that shocks the scientists.

Doctors and twins Chris and Xand van Tulleken's experiences through the Covid-19 pandemic have far more personal consequences than either could have imagined.

Chris van Tulleken takes a personal view at why ultra-processed foods are so irresistible and how they have come to dominate food culture.