Why do we get middle-aged spread?

About this episode

<p>Two cases today for Drs Adam Rutherford &amp; Hannah Fry to investigate, involving strength and weight.</p><p>The Portly Problem</p><p>"Why do we have middle aged spread?" asks Bart Janssen from New Zealand. In this episode we ponder the science of fat, from obese mice to big bottoms.</p><p>Why do we put on weight in middle age? And are some types of fat better than others? Hannah meets Prof Steve Bloom at Imperial College, London to discuss why pears are better than apples when it comes to body shape.</p><p>And Adam talks to Dr Aaron Cypess from the National Institutes of Health in Maryland, who has created a 'fatlas' - an atlas that maps fat inside the body. </p><p>The Strongest Substance</p><p>"What is the strongest substance in the universe?” asks Françoise Michel. “Some people say it is spider web, because it is stronger than steel. Is it iron? Is it flint? Is it diamond because diamond can be only be cut by diamond?" </p><p>Adam and Hannah put a variety of materials, from biscuits to toffees, under the hammer to test their strength. </p><p>In their quest to find the strongest substance on earth they quiz materials scientist Mark Miodownik, engineer Danielle George and spidergoat creator, Dr Randy Lewis from Utah.</p><p>Please send your Curious Cases for the team to investigate to curiouscases@bbc.co.uk</p><p>Photo: A man works out at a slimming centre in Beijing, credit: LIU JIN/AFP/Getty Images</p><p>Presenters: Adam Rutherford, Hannah Fry Producer: Michelle Martin</p>