For almost 3 wks now, I have been eating small meals every 3 hrs. And as of the last couple days, I have my own built in timer... I can be busy doing other stuff and then ill start to feel hungry.. so I go to check the time and every time it is within minutes of being exactly 3 hrs from the last time I ate... Coolest weightloss tool EVER! Lol
that my dear, is your circadian rhythm at work :) (aka internal clock). the human body is designed to work best with a predictable, regular schedule for eating and sleeping. when you eat around the same time every day, your body will learn to feel hungry at those times; same goes for sleeping.
it's also why those who travel across time zones reguarly or don't have a regular schedule always feel "off" -- like constant jetlag or they have digestion troubles (ie. not pooping regularly, never really hungry or hungry all the time).
when your body is set to a regular and predictable schedule, we feel at our best. this is also why it's very important for kids to be on such schedules/routines too :)