When on a special diet, you should be careful not to exceed the kilocalories that correspond to you per day.
Reading food labels is useful for keeping track of calories, but the trouble begins when dealing with fresh foods or those that do not have nutritional information readily available.
To make your job easier, we offer you an online calculator for kilocalories and nutrients of foods.
To use it, you simply have to enter two pieces of information: firstly, the food and, secondly, the amount of it.
The tool will give you the nutrients, energy, and other characteristics about the specified amount of the product in question.
Manual Calculation of Food Kilocalories
The traditional method for estimating the amount of kilocalories of a food is carried out in a laboratory using a calorimeter. Based on its heat production, its energy contribution is counted.
Currently, food manufacturers, in addition to declaring the caloric contribution of their product, must also specify its nutrients. They do so relying on the scientific method of Willbur Olin Atwater, who was the creator of the first caloric table of foods.
In 1890, Atwater and his team studied about 500 foods approximately, creating a table where they declared the kilocalories, proteins, fats or lipids, and carbohydrates of the foods, as well as water.
In a world in continuous evolution, anyone who has a phone, or a computer, with the right application (like the calculator on this page) can easily calculate and control the kilocalories consumed during a day.
Without the need to resort to any technology, you can also do your manual calculation of food kilocalories.
For this calculation, it is essential to learn and keep in mind the correct way to quickly calculate how many calories a food has, knowing only the amount of lipids (fats), proteins, and carbohydrates it contains.
To do so, you will need to have at hand the numbers we are going to give you in this table:
Macronutrients | Energy value per gram |
Carbohydrates | 4 kcal/g |
Proteins | 4 kcal/g |
Lipids (fats) | 9 kcal/g |
Atwater Factor
The values indicated in the table are the result of a study on nutrition carried out by Wilbur Olin Atwater, who first studied the behavior of the energy released by foods within the organism.
The result showed how the organism was capable of absorbing 97% of carbohydrates, 95% of lipids, and 97% of animal proteins (78% for plant proteins due to the variation of the amino acid profile).
If you want to calculate the calories of a food, you must multiply the numbers from the previous table by the amount of the corresponding macronutrients of the same.
Example of calculation
50 grams of chickpeas contain 31 grams of carbohydrates, 10.23 grams of proteins, and 3 grams of lipids.
Multiply the 31 grams of carbohydrates by 4 Kcal/g, the result is 124 kcal.
Now it's the turn of the 10.23 grams of proteins by 4 Kcal/g, the result is 40.92 kcal.
Finally, the 3 g of lipids by 9 kcal/g, the total is 27 kcal.
Now we just add the three results: 124 + 40.92 + 27, which gives us a total of 191.92 kcal.
The data in the table we showed you above (although accurate) represent an average value and may undergo some variation (up to 9.5%) that are caused by one or more factors, some particular cases would be:
The calories derived from lipids or fats are approximately 9.5 kcal/g, while those from plant-based fats are 9.3 kcal/g.
The calories from carbohydrates (such as nuts) are 3.75 kcal/gram while those containing carbohydrates from cereals, starches, tubers, and fruits are 4.22 kcal gram.
It's not just energy: don't forget the nutrients
Counting calories is very useful for maintaining a balance between the energy you consume and the one you spend. If you want to lose some pounds, the quality of the foods as well as their energy contribution is important.
It will never be the same to follow a 1500 kcal diet that contains fish, chicken, cereals, vegetables, and fruits to one of the same amount of kilocalories in which only pastries and fried foods are consumed.
Many of these data can be obtained with our tool: proteins (amino acids), lipids (trans, saturated, etc.), carbohydrates (fiber, sugar, etc.), minerals, vitamins, water, cholesterol, caffeine, alcohol, and many nutritional characteristics.
Calories or Kilocalories?
It is common to refer to the energy we consume (or that we spend) as calories or kilocalories. Notice how the labeling of foods and nutritional composition tables always appear expressed as kcal.
You might think that calorie and kilocalorie are the same, but that is a mistake. The truth is that a kilocalorie is the amount of energy to raise the temperature of 1 kilo of water by one degree Celsius. When extrapolated to the calorie, it would be the amount of energy to raise the temperature of 1 gram of water by one degree Celsius.
In short: 1 kcal is equivalent to 1000 cal, our body weight is expressed in kilos so it is more practical to say that a person of 55 kg requires 2000 kcal, rather than saying that the same person requires 2,000,000 cal.
Taking that into account, foods must indicate the amount of energy they offer in terms of kilocalories.
We hope this article has helped you solve all your doubts on the subject, if so, do not hesitate to share it on your social networks with all your contacts, thus helping this community to grow.
Finally, if you find errors in this calculator you can contact us so that we can solve it as soon as possible.
Bibliographic references
University Clinic of Navarra. Medical dictionary. Kilocalories. Available at: https://www.cun.es/diccionario-medico/terminos/kilocaloria
Biographies and life. The online biographical encyclopedia. Wilbur Olin Atwater. https://www.biografiasyvidas.com/biografia/a/atwater.htm
Lozano, José. Nutrition is Science. University of Murcia. 2nd Edition. November 2011. Available at: https://www.um.es/lafem/Nutricion/Contenido/Libro_completo.pdf
U.S. Department of Agriculture, Agricultural Research Service. 2018. USDA National Nutrient Database for Standard Reference, Release. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/nutrientdata
U.S. Department of Agriculture, Agricultural Research Service. 2018. USDA Branded Food Products Database. Nutrient Data Laboratory Home Page, http://ndb.nal.usda.gov
