The key difference between calories and kilojoules is that one calorie equal 4.184 kilojoules.
Calories and kilojoules are units that we can use to measure the energy. Usually, we use these two words in measuring food energy. It is necessary to indicate the amount of energy contained in each food item on their packaging. Some countries indicate the energies of food in calories, and some countries indicate it in kilojoules.
1. Overview and Key Difference
2. What are Calories
3. What are Kilojoules
4. Side by Side Comparison – Calories vs Kilojoules in Tabular Form
What are Calories?
We can define a calorie as “the amount of heat energy required to raise the temperature of 1 gram of water up by 1 oC.” We use this unit mainly in measuring the food energy. 1 kilocalorie equals 1000 calories. Typically in food packaging, the manufacturer gives the energy value in kilocalories or the word “Calorie”, (note the capital “C” at the beginning of Calorie) which has the same meaning as kilocalorie. Therefore, “calorie” and “Calorie” have two different meanings in food chemistry.
Obesity is a common problem; therefore, people concerns about the calories they take into their bodies. Not only for this, it is important to know the energy amount of food we are taking, in order to maintain a healthy body. We need food for our body to produce energy. For example, 1 g of carbohydrate and 1 g of protein normally contain 4 Calories and 1 g of fat contains 9 Calories. The food we are taking in, undergo a process called metabolism. In this process, the chemical energy stored in food converts into the chemical energy of ATP. Our body needs ATP to provide energy to all the functions in the body.
Furthermore, if there is an excess amount of calorie consumption than the calories burned in the body, then this calorie stores as fat in our body. As a result of that, the body weight will increase. To control the weight gain, people can increase the burning rate of stored fat by exercising. However, if the consuming energy is less than what we want, then the body weight reduces. Different people need different calorie intakes per day depending on age, gender, size, environment and their daily activities. For instance, children, athletes, and hardworking people need more energy than elderly people.
What are Kilojoules?
Kilojoules are the SI unit to measure energy. 1000 joules are equivalent to a 1 kilojoule. Joule has different definitions based on the form of energy that we measure with it. We can define it as the energy needed to apply a 1 force of Newton to move 1 m distance.
In terms of electric energy, it is the work required to move an electric charge of one coulomb through an electrical potential difference of one volt. Furthermore, in terms of food chemistry, 1 kilocalorie/Calorie is equal to 4.184 kilojoules. Likewise, this term has a different definition depending on the type of energy we are going to measure.
What is the Difference Between Calories and Kilojoules?
Calorie is the amount of heat energy required to raise the temperature of 1 gram of water up by 1 oC while kilojoules are the SI unit to measure energy. Though we can use both these terms to measure the energy of food, the values they express are different from each other. Therefore, the key difference between calories and kilojoules is that one calorie equal 4.184 kilojoules. Moreover, a calorie is a larger unit to measure energy when compared to kilojoules.
Furthermore, another important difference between calories and kilojoules is that we use calories to measure the energy of food whereas the unit kilojoule is useful in a wide range such as for electric energy measurements, chemical energy, food energy, etc.
Summary – Calories vs Kilojoules
There are several units that we can use to measure energy. The SI unit is kilojoules. However, regarding food energy, we measure the energy mainly in calories or kilocalories. But we can use the term kilojoules as well. Thus, these units express different amounts of energies. Hence, the key difference between calories and kilojoules is that one calorie equal 4.184 kilojoules.
1. “Kilojoules Explained.” SA Health. Available here
2. “Calorie.” Wikipedia, Wikimedia Foundation, 6 Nov. 2018. Available here
1.”34517645532″ by franchise opportunities (CC BY-SA 2.0) via Flickr
2.”Good Food Display – NCI Visuals Online”By Unknown – National Cancer Institute, an agency part of the National Institutes of Health, with the ID 2397 (image) (next)., (Public Domain) via Commons Wikimedia
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