Thanksgiving is just around the corner, and for many of us that means spending days lounging about with bloated stomachs and nursing hangovers after one too many.

But what’s the science behind such over-indulging and why do our bodies feel so full after eating too much?

The answer is revealed in a video that explains why too much turkey during the festive period can leave you unable to swallow another morsel of food.

Scroll down for video

The video analyses all of the major components of a Thanksgiving dinner - ans shows exactly what they do to our body.

3,000 CALORIES IN ONE MEAL The average adult consumes 3,000 calories and 229 grams of fat in one Thanksgiving meal. A 160-pound person would have to run at a moderate pace for four hours, swim for five hours or walk 30 miles to burn off those calories. Advertisement

The video was created by the American Chemical Society’s YouTube channel Reactions.

'The season of giving is often also the season of over-indulging at the dinner table,' it said.

'As Thanksgiving approaches, Reactions takes a look down at our stomachs to find out what happens when you overeat.'

They explain that, when you eat a big meal, part of the reason you can feel full is down to the size of your stomach.

‘Your stomach can stretch the volume of about one litre; that’s about the size of a burrito,’ the narrator says.

‘When you eat a big meal you fill your stomach to its limits, squeezing against your other organs and making your abdomen feel, well, full.’

When eating your stomach and intestines also fill with gases, not only from food and drink but also gulps of air when you swallow anything.

This additional air adds to the swollen sensation you get after eating.

It also reveals how what we drink affects us - and how carbon dioxide in fizzy drinks can be behind the overwhelming urge to belch at the dinner table

In the video on their Reactions page they detail the processes taking place (illustrated) when we over-indulge in certain foods. Our stomach has a finite size and squeezes other organs when it's full

Fizzy drinks can make you feel especially full, as the gas that makes them fizzy - namely carbon dioxide - can fill more space than the liquid it came in.

Your body can get rid of this gas though - in the form of burps and other methods that don’t need to be explained.

‘For some people another uncomfortable result of a big meal is heartburn,’ the video continues.

IS THE URGE TO EAT TOO MUCH DOWN TO HORMONES? In 2012, Robert Lustig, a professor of clinical paediatrics at the University of California, explained a new scientific theory on why people eat too much. He argues that the urge to overeat and lounge around doing nothing is not a sign of weakness. It is, he says, a hormonal issue, triggered by eating too much sugar. He points the finger of blame at the hormone leptin, which acts like an appetite thermostat. As one of two ‘hunger hormones’ in the body, leptin works to decrease the appetite (its partner, ghrelin, increases appetite). When you have had enough to eat, your fat cells release leptin, which effectively dulls the appetite by instructing the brain that it’s time to stop eating. But Professor Lustig warns that our sweet tooth can send this process haywire and, if you are leptin-resistant, food never stops tasting delicious, no matter how much of it you choose to eat. Advertisement

‘The stomach produces hydrochloric acid to break down food. More food to break down means more acid, which can creep into the oesophagus, leading to that burning feeling.’

Antacid tablets can alleviate this pain using bases, which are at the opposite end of the pH scale, to neutralise the acids.

Doing this, however, can release more carbon dioxide and increase the feeling of being full.

But it’s not just on a physical level that you can feel full; your brain also sends signals to stop you eating when it thinks you’ve had enough.

It releases a hormone called leptin when the amount of fat in your body reaches a certain level, which inhibits hunger.

In addition, the video says: ‘When you eat a high-calorie meal, cells in your intestines secrete a hormone called peptide tyrosine-tyrosine, or PYY.

‘When PYY reaches the brain, it binds with receptors that give you the feeling that you’re full. Maybe even a little queasy.’

The video reveals how Thanksgiving can boost our stomach by up to a litre

Ingesting air and gas can also lead to people feeling more bloated, while our brain also sends out hormones to warn us to stop eating when it detects we've got too much fat in our bodies. The bloated feeling will be felt by many come Thanksgiving (stock image shown)

Other hormones also have a similar purpose, to get you to stop eating when you’ve had too much.

But for some, come Christmas time, there’s simply too much delicious food available for any notice to be given to these hormones.

And instead, they’ll be left to deal with the biological repercussions of over-eating.