Our stomachs do important work in breaking down our food. Some people who are very fat get an operation to make their stomach tiny, so they can only eat little bits of food; and they lose weight. There's also an operation where the stomach is totally removed, if it has cancer. The end of the esophagus is then connected to the beginning of the small intestine. The people with this operation have problems with getting enough food and vitamins into their bodies.

The important role of the stomach is to break down food we eat so we can absorb the nutrients. The stomach is very acidic which is important for activating the cellular machinery that breaks down all fats, proteins, and sugars. The body needs nutrients in their simplest form to build new molecules and make energy. Therefore, large molecules that we eat need to be broken down. So without a stomach, food would go straight to your intestines where food is usually absorbed. Since your intestines can only absorb small molecules, a very small amount of the large molecules in food would be used by the body.

Most of the food we eat would pass straight into the feces. Also, the acidity of the stomach is important for killing some bacteria that we eat. So if we didn’t have a stomach, more microbes would get into our intestines and we would get sick far more often.

Do you mean if humans did not have a stomach at all or if your stomach were removed? We can learn the answer to the first question by answering the second one.

Your stomach helps you break down food mechanically (by squishing it) and dissolving it (by releasing acid). However, your intestines do most of the work absorbing liquid and nutrients from what you eat. This is why you can easily survive without your stomach. Some people choose to have all or part of their stomach removed for health reasons (called gastric bypass surgery). However, they do need to change what and how they eat to make up for not having a stomach.

Without a stomach to store eaten food, they may need to eat smaller meals but eat more often. They also need to break up their food in small pieces when eating or avoid food that is difficult to digest, like meats and other proteins.

So what if humans never evolved to have stomachs in the first place? Biologically, we’d be very similar to how we are now. We couldn’t eat as many types of food as we do now and we’d have to be more careful about what we eat. We might need to spend more time finding and preparing food. What do you think? How would your life be different if you took twice as long to find and eat food?