Your Digestive System: Energy, Macros & Micronutrients

Your body needs energy to function, but how does that happen? It starts with the foods you eat. Whether you eat a cupcake, kale or a T-bone, food provides calories, essential macronutrients (e.g., fat, protein, carbs), vitamins and minerals. 

How do you get energy from food?

During the digestive process, foods are broken down into macronutrients and micronutrients. Eventually, you’re left with glucose molecules, the prime source of energy for your body. Your blood delivers glucose and oxygen to cells. Those cells release carbon dioxide and water into your lungs and kidneys, where they are eliminated. 

ATP (adenosine triphosphate) is left over. This tiny molecule is the simplest form of energy, and it fuels every process in the body. Your mitochondria, or cellular powerhouses, can also make it.

What are macronutrients? 

The foods you eat provide macronutrients. There are four (plus water): carbohydrates, proteins, fats and fiber. 

Carbohydrates: Carbs are sugar molecules that are either simple or complex, based on their chemical bonds. (Fiber is technically also a complex carb.) Carbohydrates serve as an energy source (especially for the brain), they help maintain blood glucose and they assist with the metabolism of cholesterol. 

Fiber: There are two basic forms of fiber, soluble and insoluble. There’s also fermentable fiber, an indigestible carbohydrate the gut microflora can easily metabolize. Fiber promotes regularity, satisfies hunger and supports the work of probiotics.

Protein: Proteins are chains of amino acids linked together. Throughout the digestive process, those chains are broken down into the most basic structures. They support tissue growth and maintenance (including muscle tissue), carry messages between cells and tissues, help store and transport nutrients and form the structure of cells and tissues, among other roles. 

Fats: Dietary fats are saturated or unsaturated based on their chemical structure. Fat is an important energy source for the body. Fatty acids are the building blocks of dietary fats. Fats play a role in skin and hair health, and they help with the absorption of fat-soluble vitamins (vitamins A, D, E and K). 

What are micronutrients? 

Micronutrients are the vitamins and minerals provided by food. They are called “micro” nutrients because the body only needs small amounts of them. These vitamins and minerals are “essential” because the body cannot produce them, so they must be obtained through food or supplements. 

They include: vitamins A, C, D, E and K and the B vitamins; calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, sulfur, cobalt, copper, fluoride, manganese and selenium.