Anatomy and Physiology


Lt Col Phillips
In order to understand how people can accumulate excess weight, it’s important to know why our bodies need food in the first place. To explain the process of digestion, let’s check in with Dr. Bethea.

Dr. Bethea
Thank you, Dr. Phillips. Every part of our body needs energy to work, whether it’s our muscles, brain, or lungs. This energy comes from the foods that we eat.

Digestion begins as soon as we start chewing because the enzymes in our saliva start to break down our food. This process continues in the stomach as acids and other fluids are mixed with what we’ve eaten. The carbohydrates in the food are then further broken down into a type of sugar called glucose.

This glucose is then absorbed into the bloodstream through the stomach and small intestines, and once glucose is in the bloodstream, the body can begin to use it for energy. Any excess glucose that is not immediately used can be stored as energy to be used at a later time.

In order to both store and use glucose for energy, the body needs a hormone called insulin. When glucose enters our bloodstream, the beta cells in the pancreas are triggered, releasing insulin into the bloodstream. The insulin then travels to the body’s cells in order to open the cell doors, allowing glucose to enter. This is where the glucose is either converted into energy for immediate use, or stored for later use.

So, if you eat a large meal, some of the glucose will be used for a variety of functions as soon as it’s converted to energy, whether it’s physical activity, cell repair, or even the energy required to eat. After the body determines how much energy it needs for immediate use, the insulin converts the excess food into larger bundles of glucose called glycogen, which is stored in the muscles and the liver. Once the insulin has done its job of delivering glucose into the cells, the pancreas will detect the lower levels of sugar in the blood, and will slow down the creation of insulin. This rise and fall of blood sugar occurs many times during the day and night, depending on when and how much we eat.

In addition to handling glucose, insulin also helps our bodies store fat and protein. Protein is used when our bodies work and grow, and fat helps to protect nerves, as well as manufacture other important hormones. And, fat can be used as an energy source as well, so it’s important to note that not all fat is bad.