The calorie is the unit that expresses thermal energy .
Calorie is a unit that does not belong to the International System of Units . Its function is to express thermal energy , indicating the amount of heat needed, with normal pressure, to increase the temperature of 1 gram of H2O by 1ºC (from 14.5 to 15.5°C).
In the International System , the calorie must be replaced by the joule (one calorie is equivalent to 4.1855 joules), although its use is preserved since it has become popular to express the energy power that foods possess.
Types of calories
It is possible to differentiate between two specific classes of calories: the gram-calorie (also known as small calorie ) is the heat energy that is necessary to raise the temperature of 1 gram of H2O by 1º Celsius.
The calorie-kilogram (or large calorie ), on the other hand, is the heat energy required for the temperature of 1 kilogram of H20 to increase by 1º Celsius. This distinction, however, has fallen into disuse in recent years.
Importance in nutrition
The notion of calorie is important to explain how the food process works. Living beings need energy to survive; This energy is obtained from food . Food, therefore, is the most relevant source of energy for living organisms.
The energy obtained from nutrients found in food is converted into calories or, more precisely, kilocalories (that is, thousands of calories). The body uses calories in diseases , stress situations and metabolic processes.
Many people choose low-calorie foods to avoid gaining weight.
The obsession with calories
The number of calories present in a food must be specified on its label. This amount is responsible for informing the energy value of the food and is very important both to maintain the ideal weight and figure, and to try to recover them. When preparing a dish, it is essential to know how to differentiate between the different types of ingredients, use the appropriate proportion of each and choose the best cooking method.
Regardless of weight problems, many people have developed a kind of obsession regarding the calorie content of foods. The main reason is that at present we have access to a lot of information about the effects of foods on health , as well as their relationship with certain chronic non-communicable diseases, among which are diabetes, hypertension and cardiovascular disorders.
Understanding the nutritional properties of foods is essential to direct our diet in a healthy direction and to ensure that this becomes a lifestyle and not a simple passing practice. To understand each of the values indicated on the packages, bottles and wrappers, it is highly advisable to ask a nutritionist for help.
Analyzing the energy value
Many times, due to lack of information and tools to understand the energy value of foods, they are judged incorrectly and more calories are ingested than expected. A clear example is avoiding eating one chocolate cookie and replacing it with twenty cereals.
It is very important to know the distribution of the so-called macronutrients in each food and the number of calories per gram they provide: carbohydrates and proteins, 4; fats, 9; and alcohol, 7. To facilitate the comparison of the calorie content of various products, it is always calculated based on 100 grams of the food in question.
The more water a food contains, the less energy it provides; In the case of vegetables, for example, almost 95% of their weight is wet. On the contrary, products such as bread and nuts have a high energy value, given the small proportion of liquid present in their composition. Fats, on the other hand, are the nutrients that add the most calories; This is the case of oils , butter and margarine, among others.