A weight loss secret may be lurking in lizard spit. Swedish scientists found that exendin-4, 
a compound in the saliva of Gila monsters, reduced food cravings in rats. The reason? Exendin-4 inhibits the dopamine rush that makes you crave sugary, fatty foods. Synthetic versions of the compound are already used to treat type 2 diabetes, but research is needed before it can be used for weight loss, says study author Dr Karolina Skibicka.