If you've ever beaten yourself up after eating an entire pint of ice cream, know this: it's really not your fault. According to obesity researcher and neurobiologist Stephen Guyenet, author of The Hungry Brain and founder of the wellness and science blog Whole Health Source, millions of years of evolution have hardwired us to seek out sugary, fatty, and salty foods. All those calories kept us alive back when we were hunter gathers. Today, they just make us fat. Outside editor Chris Keyes sits down with Guyenet to discuss why we feel so powerless in the face of decadent desserts, how different systems in our brain compete for dominance, and what we can do to combat all this temptation.