We hear about calories all the time: How many calories are in this cookie? How many are burned by doing 100 jumping jacks, or long-distance running, or fidgeting? But what is a calorie, really? And how many of them do we actually need? Emma Bryce explains how a few different factors should go into determining the recommended amount for each person.
This week, we meet a girl whose heart has formed outside her ribcage, a man who can spend nine minutes underwater without taking a breath, a woman who is growing a second skeleton and a paralysed man who is regaining movement thanks to a chip implanted into his brain that can 'read' his brain signals.