Since the birth of their trademark toy in 1958, The LEGO Group has produced over 400 billion bricks. But more and more, LEGO bricks aren't just for kids, and some take them very seriously. Adult Fans of LEGO around the globe are unashamedly declaring their love of the brick, brick artists are creating stunning and surprising creations, and LEGO master builders are building human scale and larger structures. LEGO bricks are being used educationally, therapeutically, and have provided a universal system for human creativity and our innate desire "to build." This documentary playfully delves into the extraordinary impact of the LEGO brick, its massive global fan base, and the innovative uses for it that has sprung up around the world.

Horizon investigates the idea that the best way to lose weight successfully is a personalised approach, diets tailored to our individual biology and psychology. In a groundbreaking experiment, Dr Chris van Tulleken and Tanya Byron join a team of experts to put 75 overweight volunteers on diets designed to tackle the specific reasons why they eat too much. The volunteers are put through a series of tests at a residential clinic to understand how their genes, hormones and psychology influence their eating behaviour. They are then put on the diets the experts believe are best suited to them. Can science succeed where other diets have failed?

The final part reveals how our knowledge of cells has brought us to the brink of one of the most important moments in history. Scientists are close to repeating what has happened only once in four billion years - the creation of a new life form.

Michael Pollan looks to the kitchens of India for a lesson in the value of pot cooking and examines the consequences of eating highly processed food.