Why do we eat and what does it do to us? This week Karl and Adam examine the science of eating and energy. Karl explains how eating determines our body temperature, and he illustrates the theory by showing a marathon runner collapsing just before the finish line (hyperthermia) and his daughter diving into sub-zero Antarctic waters (hypothermia). Adam takes a group of volunteers on a power walk to show just how much work they have to do to burn off their guilty pleasure. Did you know there are 17 teaspoons of sugar in a can of carbonated soft drink? Ruben sets light to a gummy bear to show how much sugar there is in the innocent looking sweet. We decode the Basal Metabolic Rate (the formula will be available on the website) and explain the process of digestion. We meet a fidgetter, whose constant moving and twitching helps him maintain a healthy weight. Karl debunks the belief that you can lose weight by eating celery. An audience member tries to work out which task takes the most energy in the Rank-o-meter (vigorous arts and crafts, surfing, butchering animals, tai chi) which leads to a discussion on the MET rate – which is the rate at which you burn off energy. We reveal Elvis’s diet and the king makes a rare appearance to perform an even rarer original song ‘Burning Hunk of Lard’.