We all enjoy a deep-fried Mars bar with french fries from time to time, but why do we crave these unhealthy foods instead of healthy things like spinach or broccoli? And what is a food craving? The answers lie in a complex blend of our psychology, physiology, and even sociology. BBC CrowdScience presenter Alex Lathbridge savours a mystery-meat crocket with the experts on a quest to discover the hidden sources and sauces of our food cravings. Presenter: Alex Lathbridge Producer: Richard Walker Editor: Richard Collings (Image: Stack of cheeseburgers and French fries. Credit: Dominic Lipinski/PA)