\u201cEat like an emperor in the morning, like a king at noon, and like a beggar at night\u201d\u2014this old dietary rule sounds more like some\u00adthing from Grandma\u2019s kitchen than modern meta\u00adbolic rese\u00adarch. Yet it\u2019s appar\u00adently not enti\u00adrely without basis. That\u2019s because the body processes a meal differ\u00adently in the morning than it does in the evening.<\/p>\n
When the Body\u2019s Internal Clock Comes into Play<\/strong><\/p>\n After eating, energy expen\u00additure tempo\u00adr\u00ada\u00adrily increases: diges\u00adtion, absorp\u00adtion, trans\u00adport, and storage of nutri\u00adents all require energy. This diet-induced thermogenesis\u2014DIT for short\u2014apparently follows its own circa\u00addian rhythm.<\/p>\n This is demons\u00adtrated by a recent study invol\u00adving 16 adults who were over\u00adweight or obese. To isolate the influence of the body\u2019s internal clock as clearly as possible from sleep, exer\u00adcise, light, and usual meal\u00adtimes, the parti\u00adci\u00adpants spent 36 hours under strictly controlled condi\u00adtions and were given iden\u00adtical meals every six hours. DIT peaked in the biolo\u00adgical morning and reached its lowest point in the evening. The diffe\u00adrence between the peak and trough values was initi\u00adally 44 percent; after accoun\u00adting for resting energy expenditure\u2014which also fluc\u00adtuates circadianly\u2014the diffe\u00adrence was reduced to about 29 percent.<\/p>\n