#3. Your Friends
It's no secret that your friends secretly hate you. They're probably making fun of you behind your back, and having sex with your girlfriend right now. But could they be subliminally influencing your eating habits, to make you less attractive than they are? Just so they'll look thinner by comparison?
Yes. You should confront them about this immediately.
After all, science has your back. Okay, maybe they aren't actively conspiring to shove food down your unwilling gullet (though we wouldn't rule it out completely). However, in a study that the Psychological Bulletin briefly titled "Effects of the Presence of Others on Food Intake: A Normative Interpretation," it was discovered that each additional person at the dinner table means another 20% or so consumed by all present.
Think about it: assuming you actually like the people you're eating with, chances are you're going to engage in some form of pleasant conversation over the meal. A happy mind is a distracted mind, one that pays less attention to food intake and feelings of fullness.
Of course there's also the way people reinforce each others' bad behavior ("No desert for me. Unless you wanted something... okay, waiter, we're both having the bacon ice cream cake").
Since these folks are your pals, you're probably going to want to linger over your meal, get a dessert or some booze, or coffee. Three slices of stale cheesecake, a bottle of vinegary red, and 90 minutes later and you find yourself wishing for larger pants (when you should probably just wish for healthier friends.)
#2. Your Mom
Remember when your mother told you to clean your plate? You know, because of those starving kids in Africa? Most of us are programmed to eat until we see the bottom of the dish.
But why are we still following Mom's advice well into adulthood? Well, basically your stomach is an idiot. It has absolutely no way of quantifying exactly how hungry you are. Your brain is the smart one, it handles the numbers and shit. Except for the little fact that your brain has no idea how hungry you are either, because your stomach, the stupid one, is pretty much completely in charge of the whole diet operation.
It takes your stomach about twenty minutes to even signal to your brain that it has received food. Having no other information to work with, your brain takes one look at the food you've piled on your plate and thinks to itself "Shit, I guess that looks about right."
Just ask Cornell Food and Brand Lab, who performed a study/prank involving bottomless soup bowls and unsuspecting restaurant patrons (the best kind!). Some diners were given regular bowls of tomato soup, while others were given bowls connected to tanks of soup which was piped invisibly into the bottom of the dish.
The diners eating from the regular bowls consumed an average of nine ounces per person, about the equivalent of a regular can of soup. Diners eating from the bottomless bowls wolfed down at least twice as much, some devouring more than a quart.
The study stops at this point, but we assume that these patrons didn't actually stop eating until soup was pouring so readily from every one of their orifices that no more could be forced in, at which point the researchers giggled and prepared to upload a video to YouTube.
#1. Using the Internet
Yeah, yeah, we know, we can hear you now: "Holy smokes! You mean that sitting nearly motionless for hours on end isn't very good for me?! Be sure to let me know when you work out the whole 'water wet, sky blue' thing, assholes." It's more complicated than that. So quit it with the sass.
There are these neat little communiques between your stomach and your brain called "orosensory signals of satiation." They're the signals your stomach sends off when it's full to let the brain know when it's time to stop shovelling Cheetos down.
Unfortunately, orosensory signals are like anemic little schoolgirls when pitted against all the other things that constantly vie for your brain's attention, and have a nasty habit of getting shoved aside by bigger, stronger signals. Distracting signals like these clog up your brain all the time when you're doing something fun, like surfing the net.
Imagine that the cameraman is your brain. Your stomach is the guy with his hands in the air.
So you're sitting there, eating chips with one hand and moving the mouse with the other. Have you had four handfuls, or five? How full was the bag when you started? Don't ask your stomach, it's retarded. And your brain is too busy handling the sensory information provided by that .gif of the dramatic hamster to care.
So that pretty much leaves... well, no one. According to a study from the American Journal of Clinical Nutrition, the damage works out to eating about fifteen percent more of your snack while distracted. You might as well have a monitor that fires little sausages into your mouth.
Uh, we're going to have to stop now. We have a patent application to fill out.
Avoid being fat and a obnoxious by reading 5 Douchebag Behaviors Explained by Science. Or find out about what most of you have in store in 6 Terrifying Things They Don't Tell You About Childbirth.