The world is affected by an obesity epidemic, but why is it that not everyone is succumbing? Medical science has been obsessed with this subject and is coming up with some unexpected answers. As it turns out, it is not all about exercise and diet. At the centre of this programme is a controversial overeating experiment that aims to identify exactly what it is about some people that makes it hard for them to bulk up.

The world stood in fear of an emerging new disease that threatened to kill millions. A new flu variant H1N1 had arrived. If this latest pandemic has taught anything, it is just how little is understood about the invisible world of viruses. But that has not stopped scientists trying. Horizon follows the leading researchers from across the world, who are attempting to unravel the many secrets of viruses to understand when and why they kill.

In this film, which spans all episodes of the series, Michael Mosley takes a fascinating journey around the human body to find out how it works. What makes our bodies work and what is really happening on the inside when they go wrong? Using the latest science and medical innovation, Michael delves inside our bodies to reveal the extraordinary marvels which lie within.
In each episode, Michael is on the case to find out about a new breakthrough which is dramatically changing how we view or understand the human body. From how new organs might soon be 3D printed to gene therapies that promise to reverse blindness. From test that could predict heart problems years in advance to cold water swimming benefits and risks. Along the way, Michael delivers extra insight in his inimitable way, by offering up his own body for ground-breaking demonstrations. Made by an award winning science and factual production team, this series is packed full of amazing visuals and fascinating facts.