"Why do we have middle aged spread?" asks Bart Janssen from New Zealand.
From obese mice to big bottoms, the duo discovers what science can tell us about fat.
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 apples and pears.
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.
Please email your Curious Cases for the team to investigate to: curiouscases@bbc.co.uk
Presenters: Hannah Fry & Adam Rutherford Producer: Michelle Martin.