You know the feeling. You finish a full mealand are like…"I’m never eating again."But then, out comes a beautiful piece of cake.And, well…."You said you were full!""Not for dessert."Turns out, you really can "make room” fordessert.And there’s a scientific reason why.The thing that gives you room for dessertis called “Sensory-Specific Satiety.”Satiety! It’s one of those words.That’s Dr. Barbara Rolls. She’s a nutritionalscientist,and she’s been studying Sensory-Specific Satiety since the ‘80s.It’s a really important, basic and veryreproducible finding about human eating behavior.Dr. Rolls says it’s why we often misunderstandthat “full” feeling.So, to see it in action, we ran an experimentsimilar to ones she’s done before:We gave six people a giant plate of mac andcheese..."Wow. That is a lot of macaroni and cheese."...and told them to eat until they were full.And then, for the second course, we gave them…more."Nooo!""I’m not happy with this experiment."Then, on a different day, we did it all overagain.Except this time, after they were full, wegave them ice cream."Ice cream!""Yes."On average, after they said they were fullon mac and cheese,each person could eat just one more ounce of it in their second serving."I got a solid two bites in."But when we gave them ice cream instead, somehowthey could eat three times as much.They "made room" for dessert.The experiment shows that when you feel full,it’s not necessarily that your stomach is physically full.It’s more about howinterested you are in eating more.Sensory-specific satiety is that change inhow much you like a food, how much you wantto eat, as you’re eating it.And to really show that, we asked our participantsto rate, on a scale of ten,their interest in mac and cheese before their first course..."Probably like a six.""Five.""I love macaroni and cheese, so...25."...and after."I can’t eat anymore.""Probably like a one.""Yeah, zero."They all started pretty interested in themac and cheese. But after their first course,they were less interested. Even less so aftertheir second helping.But we also asked them, throughout the experiment,to rate their interest in ice cream.And even after getting full on mac and cheese,they stayed interested.The only thing that made them lose interestin ice cream, was having ice cream.I’ve just had enough of that food, I wantsomething else,is really what Sensory-Specific Satiety is.And that instinct has a purpose: It’s meantto keep us healthy.So it’s a good thing. We're omnivores andwe need to eat a variety. So it’s goingto help to guarantee that you’re going toeat the variety of nutrients that you need.It also means that there are certain situationswhere it makes us extra susceptible to overeating.It can backfire though of course, becauseif we are presented with a variety of foods,it encourages us to keep eating.Ever eat too much at a buffet?Or on Thanksgiving? Yeah, me too.That’s because, when we have a lot of variety,we stay interested in eating for longer.This change in the appeal of foods duringa meal keeps us going, keeps us eating.In another experiment, Dr. Rolls gave differentfour-course meals to two groups:One where every course was the same food, and one where every course was very different.The people with different foods ate 60% more.Sensory-Specific Satiety is why you’ll eatmore french fries with condiments than without.Why you’ll eat more ice cream if you getmultiple flavors than just one.It’s also why kids will eat more veggiesif they can eat a variety of them together,than if they only have one option."That’s interesting.And it only took me eating a ridiculous amount of mac and cheese to learn it."There's a scientific reason behind your "second stomach." Become a Video Lab member! http://bit.ly/video-lab How is it that, after stuffing ourselves full at dinner, we somehow find room to eat again once dessert comes around? Turns out, the thing that makes us do this has a name: It's called "sensory-specific satiety," and it's actually supposed to keep us healthy. Vox.com is a news website that helps you cut through the noise and understand what's really driving the events in the headlines. Check out http://www.vox.com. Watch our full video catalog: http://goo.gl/IZONyE Follow Vox on Facebook: http://goo.gl/U2g06o Or Twitter: http://goo.gl/XFrZ5H