Science Explains: Stuffing yourself at Christmas

Picture this: you’re sat at the dinner table on Christmas Day, having just eaten what probably was your largest meal of the year, and you’re feeling full. Then comes the inevitable, you get offered dessert. Kudos to you if you have the willpower to say no, but if you’ve still got plenty of room – here’s why.

While it may not be medically accurate to say that “dessert doesn’t go to the stomach, dessert goes to the heart”, science does have an explanation for why we always have more room in our stomachs, particularly around Christmas. This is down to a phenomenon called Sensory-Specific Satiety (SSS). SSS allows you to eat one sort of food until you can eat no more, but still have an appetite for something else. This means that our brains override satiety signals (i.e. feeling full) for pleasure (i.e. more tasty food) – and gosh, isn’t this perfect for Christmas!

SSS allows you to eat one sort of food until you can eat no more, but still have an appetite for something else

In the animal kingdom, humans are omnivores – this means that we must eat a variety of food to survive. SSS is an evolutionary mechanism we developed which ensures that we get all the required nutrients we need, instead of stuffing our faces with our favourite meal all the time and risk getting ill.

SSS happens subconsciously, such that even people with amnesia who cannot remember whether they’ve eaten anything at all still express SSS. When presented with two identical meals one after the other, they did eat the second meal but found that it became increasingly unpleasant. But, when we consciously try to override SSS, an internal tug of war begins – though one that seems relatively easy to win. Studies find that to continue to eat our meals a while longer, simply introducing a condiment may be enough. So, next time you’re struggling to get through that pizza, get some garlic and herb dip (or BBQ sauce, we don’t judge) and you’ll be good to go.

But, when we consciously try to override SSS, an internal tug of war begins

So far SSS sounds like a dream, but sadly it backfires in our modern world. With restaurants offering as many courses as you could ever want, and with Christmas dinner leftovers seeming to have no end, SSS makes overeating pleasurable. Although the last thing we want to think about at Christmas is how much weight we’ll put on – save that one for a New Year’s resolution.

Eating the same food every single day, no matter how good, can lead to long-term SSS – also known as monotony. Sooner or later, we’ll get bored of eating the same thing. While one mince pie a day for the whole of December sounds like a good idea at the start, halfway through the month you’ll probably start feeling sick at the thought of even a raisin.

Sooner or later, we’ll get bored of eating the same thing

Now that science has given us an explanation for why we always seem to have a bit of room left for dessert, it’s time to indulge in your Christmas dinner!