What are the calories that obsess us so much and how are they measured?

What are the calories that obsess us so much and how are they measured?


We count them, we worry about the ingested ones or those that we burn, and sometimes they torment us because they are the price that we pay for a pleasure.

But, do you know what exactly calories are?

For a calorie is the amount of heat required to raise the temperature of one gram of water from 14 5 to 15 5 degrees Centigrade at atmospheric pressure .

However, the measure used by the American chemist Wilbur O. Atwater, the driving force behind the popularity of calories, was not strictly that.

Atwater’s was the Calorie, with a capital letter, and the difference is important.

The vital force is in the stomach

For centuries it was believed that the heat of animals – humans included – was the result of a mystical life force , until in the seventeenth century the idea that the cause was the combustion of food began to emerge.

In his “De Homine” (1662), the mathematician, philosopher and scientist René Descartes seems to have been the first to enunciate a correct theory pointing out that the change that occurred in the food in the stomach was like that produced when pouring water on quicklime.

But it was Antoine-Laurent de Lavoisier, the father of modern chemistry, who tried it with experiments.

Measuring the caloric content of the food by burning it.  The food is turned on and the heat it bounces increases the temperature of the water in the test tube.  That increase is used to calculate the amount of energy released.
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Image caption Measuring the caloric content of the food by burning it. The food is turned on and the heat it gives off increases the temperature of the water in the test tube. That increase is used to calculate the amount of energy released.

In 1780 he used a guinea pig in his experiments with a calorimeter to measure the production of heat. The heat of guinea pig breathing melted the snow surrounding the calorimeter , showing that the exchange of respiratory gas is a combustion, similar to a lit candle.

The theory of heat that he gave in 1780 his “Memory on Heat” is essentially the same as we have today.

2,000,000 calories per day

Both the instrument – the calorimeter and the measure – the calorie – were used in various sciences and, in the 1870s, the French chemist Marcelino Berthelot observed that there were two definitions for “calorie”.

He decided to define the calorie in lowercase as a g-calorie or small calorie and the Calorie in uppercase to refer to the kilocalorie.

Wilbur O. Atwater
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Image caption At water measured the caloric content of more than 500 foods.

By the time Atwater introduced it as an energy unit for food in 1887, in an article entitled “The potential energy of food”, Calorie was defined as the heat needed to raise the temperature of 1 kilogram of water from 0 to 1 ° Celsius. .

And that, with a capital letter, was the one that best suited his purpose, which was to educate .

A calorie in nutrition is actually 1,000 of the small calories but telling people that they should consume two million calories a day or talking about kilocalories to an audience that was not familiar with metric prefixes was inconvenient.

His article marked a milestone in the science of nutrition and the measure stayed forever.

Beginning in the 1890s, Atwater and his team at Wesleyan University undertook a comprehensive study on the caloric content of more than 500 foods with the intention of finding a scientific and healthy way to maintain weight.

At the beginning of the 1900s, Atwater was one of the leading authorities in terms of food intake and his advice was simple: decrease the excess and ensure a balance between food .

Pineapple with calories
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Image captionBut only if you eat it whole.

The “scientific diet”

Atwater devised a series of formulas to help people get the most energy from the least amount of food.

He united economics and physiology in what he called “the pecuniary food economy” and was a pioneer of the “scientific feeding” movement.

The idea attracted French doctors, who believed that working class families spent too much on meat and wine, says Martin Bruegel, a historian at the French National Institute of Agricultural Research, in an article published by the New York Times.

The result was a “rational feeding” program to instruct the poor to keep food expenses within the limits of their modest budgets.

They were urged to eat protein-rich legumes instead of red meat, pasta instead of sausages, and to replace the wine with sugary drinks.

Fat man and skinny man
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Image caption In a few words.

They were convinced that ignorance was the problem and information the solution.

So to inform !: nutritional information appeared on the menus of the factory canteens and working class restaurants. They even put scales on the entrance to eating places to help clients control their weight.

On boards they listed carefully calibrated culinary options for workers to assemble nutritious meals.

The program failed .

However, the Americans adopted fashion.

Scientific restaurants

In 1914 the Board of Health of the State of New York introduced a “scientific restaurant,” where staff lunches were prepared according to “the most modern dietary theories ,  says Martin Bruegel.

Restaurants across the country began to list the energy and protein content in their menus.

Exterior of one of the restaurants of the Childs chain on Pennsylvania Avenue, Washington, DC, in 1917.
Image caption Exterior of one of the restaurants of the Childs chain on Pennsylvania Avenue, Washington, DC, in 1917. (Harris & Ewing, Wikipedia)

Childs Restaurants, an ancestor of global fast food chains, provided “a complete lesson in dietetics, math, food preservation, patience, economy and patriotism, plus a plate of food” to its clientele.

The demands of the First World War made efficiency even more imperative.

In 1924, the Restaurant Owners Association sought to provide diners with printed advice on well-balanced meals “from the point of view of calories.”

Science without pleasure

None of these initiatives had any effect. For European and American consumers, copious and appetizing meals exceeded scientific formulas.

And is that food is more than a fuel .

The French continued to eat their red meats and drink their red wine because their dishes gave them a sense of belonging to a community , as Bruegel points out.

Similarly, American consumers after World War II saw access to abundant, increasingly cheaper and less healthy foods as proof of the American dream , even if the impact on their waists and their well-being has been disastrous.

Filtered calories

But Atwater’s meticulous work was not lost.

Poster with lady eating ice cream on the beach
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Image caption Little by little we were learning.

From his studies had emerged a general rule: weight-for-weight, fat contains 9 calories per gram, approximately twice as much as proteins or carbohydrates.

This led to the so-called Atwater system , which is still used, to find out how many calories food has without the need for laboratory tests: calculate the proportions of fat, protein and carbohydrates that are contained and multiplied by the relevant factor “Atwater”, which results in the total caloric content.

In addition, the calorie count was filtering in the collective consciousness .

Today it is rare to find someone who does not know how many to eat to stay healthy.

And, no matter how hard we try to avoid reality, there in the back of our mind we know that that half liter of ice cream that we ate absent-mindedly while watching television has more calories than advisable … about 1,300!

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Rava Desk

Rava is an online news portal providing recent news, editorials, opinions and advice on day to day happenings in Pakistan.


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