Will I have to work on Saturdays? http://www.prisonersonthemove.eu/introduction-to-lab-report escape saturation research paper compared There's a reason we don't crave green leafy vegetables when we're hungry. They're not energy dense, and our bodies, forged by the white-hot evolutionary crucible of floods, droughts and long harsh winters, know that in response to the body's call for calories, it's sugar and fat that will fit the bill. And, weight loss and healthful-living desires be damned, our bodies' primitive drives trump the more thoughtful desires of our brains.