It sounds like the question of a 4-year-old making his first forays into understanding life, biology, and the nature of the universe: “Mom, why do we eat?” On some level, there’s an answer that’s both basic and true – the kind with which we’d respond to little Junior: “We eat because we’re hungry.” If it – and we – were only that simple…. Beyond the hormonal cues that tell us our bodies need feeding exists an intricate constellation of reasons. They stem from the gamut of higher order thinking, social reference and self-organization that characterize the human mind. And just when you thought the biological picture was at least an easy call, it’s important to note the environmental inputs that can skew our hormonal responses and convince us we need to raid the refrigerator at midnight. (Yes, analyzing human instinct can feel like nailing Jello to the wall.) So, what are the various reasons we eat? What influenced your food intake today? Truth be told, sometimes we’re not even conscious of our simplest motivations. I thought I’d take up the multifaceted question in a series of articles. We spend a lot of time talking about what we eat/should eat, and the why can lead us down some interesting roads in terms of both research and experience. But let’s start today with the fundamental biology behind our food intake.