Do Fats Provide The Most Concentrated Source Of Energy?

Do Fats Provide the Most Concentrated Source of Energy?

Mar 6, 2011 | By Laura Niedziocha

Macronutrients describe food sources of proteins, carbohydrates and fats. You may have heard the term energy-dense to describe a food. When a food is energy-dense, it usually means that it has a large proportion of fat to its volume. Fat provides the largest amount of energy compared to any other macronutrient.

Calories

A calorie is the amount of energy that the nutrients you eat provide. When you take in nutrients, your body liberates the energy and either uses it or stores it for later use. Your body uses a set number of calories each day to function. How many calories you take in determines what your body does with the calories from the food you eat.

Fat and Calories

You can measure calories using a device called a bomb calorimeter. This machine measures the amount of heat released by a macronutrient when it combusts. Heat production is directly related to the amount of energy in a nutrient. One gram of fat is equal to 9.5 calories. Both carbohydrates and protein provide only 4 calories per gram, making fats the most concentrated source of energy.

Digestion of Fats

The digestion and liberation of calories from fat begin with your first bite. Salivary glands in your mouth secrete an enzyme called lipase that begins digesting fat. Digestion continues in the stomach as the acidic stomach juices further activate the lipase enzyme. Once the fat moves from the stomach into the small intestines, it is transformed into droplets that are degraded by bile. Fats are broken down into two free fatty acids and a glyceride and absorbed into the bloodstream. The free fatty acids are the molecules that provide stored energy.

Using Fats for Energy

Fat is the go-to form of energy storage for your body. Not only do fats provide the largest amount of energy per gram, they are also an easy way for your body to store energy for times of famine. Your body relies on fat to provide most of its energy. In fact, during periods of sustained, light activity, like resting, sitting at the computer or doing laundry or light cleaning, your body uses fat to produce this energy.