Heat Energy in Foods

All foods contain heat energy. The unit of measurement for the heat energy in foods is called a calorie. When in motion (such as exercising), the human body transforms this heat energy into mechanical energy. The balance between energy input (the intake of food) and energy output (exercise) is essential for maintaining a healthy lifestyle.

Where Heat Energy Comes From

• The heat energy in the foods we consume originally comes from the sun. Through the process of photosynthesis, plants create a sugar called glucose by using the sun's energy to recombine the atoms from water and carbon dioxide. Heat energy is stored in the glucose's chemical bond. In order to recapture this energy, the glucose's molecular bond must be broken, which is most commonly achieved by burning.

Measuring Heat Energy in Foods

• The calorie can most accurately be measured using a calorimeter. This device measures the heat output and heat capacity of food when a chemical reaction is induced. The most effective way to induce such a reaction is through burning the food under a known mass of water. The output of joules, a unit for measuring heat, results in a specific temperature rise in the water, which is recorded by the calorimeter. Energy is released from the food through an oxidation process called respiration (a process similar to combustion). The energy value of food as expressed in calories per gram can most succinctly be calculated as the temperature rise of the water multiplied by the water's volume over the mass of the food sample in grams.

Varieties of Heat Energy

• The heat energy in foods comes from three main varieties: carbohydrates, proteins and fats. Using vitamins and hormones, the human body will turn fats into proteins, then proteins into carbohydrates, and eventually carbohydrates into energy output. An excess intake of fats creates increased body weight because the body is unable to convert it all. You can more quickly convert food's heat energy by reducing the amount of fats the body takes in.

Getting the Energy You Need

• The exact number of calories a person needs is dependent on a number of factors, from body size to activity level to body weight goals. Younger, more active people with a higher metabolic rate, for instance, can generally convert food energy into energy output at a greater level than older people with a less active lifestyle and a slower metabolic rate. It is important to understand the changing needs of your body and adjust your diet accordingly in order to stay healthy.

The Most Important Meal of the Day

• Breakfast is often called the most important meal of the day because it provides the necessary energy input that our bodies need after the body has been dormant all night. A proper breakfast that meets the body's nutritional needs and provides energy will include foods from the fruit, dairy and grain groups.