How the stomach activates the digestive system


The stomach is the first station in the digestive process. Its role is to prepare the food for the intestines and to give the brain the first signals of satiety. However, these signals can sometimes also be deceptive.

Ingenious stomach anato­my: why is the stomach so slanted?

The stomach begins just below the left nipple and ends under the right ribcage. Because it slants, fluids can flow straight past its short side into the small intestine, while food falls onto the large side of the stomach. It is here that the muscular stomach wall starts working like a kneading machine, mixing and breaking down the food. Termed «retropulsion», this process gives the entire digestive tract an extra push.

For this reason, the gurgling sound we hear after a meal shows that the di­ges­tive process has started and explains why we often have to go to the toilet straight after eating.

But the stomach doesn’t only perform mechanical work: acid in the stomach kills many pathogens and bacteria. At the same time, enzymes start to break down proteins and help prepare the food for the small intestine.

A full stomach doesn't equal satiety

The stomach is also the organ that sends the first signals to the body when it is full. To do this, it needs a certain volume of food. When the stomach wall stretches, sensors in the stomach wall transmit an initial feeling of satiety to the brain. If we eat a small piece of choco­late, we've consumed a lot of energy, but we still don't feel full. The opposite is true if we drink a lot: an expanded stomach gives us the feeling of being full. But this is only short-lived.

A rumbling stomach isn't the same as being hungry

A rumbling stomach occurs when the stomach muscles contract. It pushes air that we've swallowed into the small intestine. But this doesn’t automatically mean that we are hungry: the small intestine still has food pulp to digest and wants to clean itself before the next load of food arrives.

Full for several hours, says the intestine

It is the intestines that notice whether we have consumed enough. They produce hormones as soon as the digestion process starts. Cholecystokinin and glucagon -like peptide-1 together with pan­cre­at­ic hormones give the body the signal of long-lasting satiety. But this process is far from the only thing that makes us feel satiated. Whether we're full or hungry depends on many other factors, such as eating habits and the size of the body's fat stores.

Drinking with food: yes or no?

It's a never-ending discussion: should we drink water with food or not? Opinions on the subject vary widely. Hollywood star nutritionist Kimberly Snyder recommends not drinking at all before a meal because she believes liquids dilute stomach acid and this slows down digestion. Others drink a litre of water before a meal in order to feel full faster and lose weight.

Does water at mealtimes dilute stomach acid?

There's actually no study that proves that water can dilute stomach acid and thus have any real influence on digestion. Only extreme amounts of water can have this effect. However, a certain amount of liquid with food, whether in the food itself or through a drink, boosts digestion and helps prevent constipation. The Ayurvedic diet sees the answer somewhere in the middle: drinking sips of (warm) water or herbal tea while eating aids digestion – but too much water beforehand hinders it.

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