They stopped snacking between meals, skipped some meals altogether, replaced heavy foods with lighter fare, and experimented with a number of dieting fads. The Hollywood Day Diet, for example, restricted dieters to a spartan ration of citrus fruits, melba toast, vegetables, and hard-boiled eggs, amounting to calories per day.
Calorie counting reinforced dieting practices already under way and encouraged new dieters by legitimating its promise with science. A physician of the Progressive era—then an unusual profession for a woman—Peters earned a medical degree from the University of California in Her personal struggles with weight and her own relative success with counting calories informed her conviction that managing calorie consumption was the answer to weight control.
By her own account Peters weighed pounds at her heaviest, then lost 70 pounds through calorie restriction. In middle age Peters had the appearance of a perennial, intermittently frustrated dieter. But as would be expected of the doyenne of calorie counting, Peters was unmistakably fashionable. She adorned herself in conspicuous jewelry and furs. Her eyebrows were severely plucked, and her thin, pursed lips enhanced with bold lipstick. Her dark hair was bobbed and ornamented with low-hanging headbands.
In this sense she was just like her acolytes—image-conscious and desperate to be thin. From until her death Peters promoted calorie counting for weight loss through her syndicated column and diet guides.
Like Atwater, Peters was both an adept and indefatigable advocate for herself and the calorie as a precise, infallible measurement of food. In promoting calorie counting as a way of life, she projected an assertive, didactic voice. Hereafter you are going to eat calories of food. Instead of saying one slice of bread, or a piece of pie, you will say calories of bread, calories of pie.
In insisting that dieters reimagine food as calories, Peters encouraged what amounted to a mathematization of dieting. Her mantra was that if dieters learned how many calories they would need to consume in order to lose weight and how many calories were contained in the foods they ate, they would be equipped to melt off the pounds. According to the diet guru, the average person should consume 15 to 20 calories per pound of body weight daily in order to maintain weight.
Dieters were to subtract that total by to calories a day, depending on how rapidly they hoped to lose weight. For example, Taton 7 indicates that Favre and Silbermann coined the term in Others 6 , 18 also credit Favre for defining the calorie.
However, the original publication states that the calorie was a well-known unit of physics digital copies of L. A French etymological dictionary lists the first occurrence of calorie as the —3 volumes of Bescherelle's Dictionnaire national 19 , The listing in the edition defines the calorie as Phys. The definition is similar to Ganot's more precise usage. Thus, French sources do not indicate that Lavoisier defined the calorie. By , the word calorie was being used as a unit of heat 1 , 3 , 4 , Among the students was Sadi Carnot 3 and class notes are available that were taken by L.
Francoeur and J. Baudot 2. Assuming that the mass abbreviation refers to a kg, this defines a modern kilocalorie. This is different usage from the modern kcal, but the passage indicates that the calorie was known to engineers by this time Other engineers began using the calorie by 4 , but the word apparently did not enter physics texts until much later.
It is true that some scientists used heat units that would now be called g-calories in the s. Although Medard states that the kcal was not introduced until 4 , it was used in the context of daily energy expenditure in a U. It is not certain who first named the kcal. The calorie could not be strictly defined without knowing the mass of water contained in a liter, which was based on a cm cube.
This is important because the g-calorie eventually became a practical unit of heat, and the specific heat and mass of a volume of water depend on its temperature Because the kg, g, m, and cm were all defined from the start, it is ambiguous whether the original metric system should be called m-kg-s or cm-g-s. However, the kg was considered to be the base unit of weight in the metric system.
This is because the charge to the commission was to define standards for weights and measures used in commerce, and scientific concerns were secondary. Note that the original definition specified a weight rather than a mass, meaning that the original kg was defined as kg-force, similarly to a pound. Not until was the newton defined as a unit of force so that the kg became a mass unit. Indeed, the thermal g-calorie was not defined as 4. The original metric system was short-lived as a French national standard.
Not until was a law passed to reinstate a metric system based on scientific standards During this same period, European interest in thermodynamics, fuels, and electricity was high. Indeed, one of the reasons that Joule began his experiments on heat was a desire to reduce the cost of running equipment in the family brewery Metric advocates worldwide recognized the simplicity of basing units of measure on the decimal system, and the metric system was promoted at world expositions in London and Paris Also in , the International Geodetic Association formed a committee to investigate the use of the metric system in scientific measurements.
The system was made legal for commerce in Britain and the United States and became compulsory in Germany The International Metric Convention of gave scientists impetus to define accurate standards in electricity, magnetism, and thermodynamics.
This led to the introduction of the CGS in in which the erg, dyne, and joule were defined. In , the newton was added as a unit of force to the m-kg-s system and the joule was defined as 1 N-m of work.
Keesom served as president. From then on, any secondary thermal unit was to be defined relative to the joule rather than to the heating of water at any temperature. The General Conference also recommended discarding the calorie, because it cannot be derived directly from basic units.
In , the SI base units were adopted, and in , the Committee on Nomenclature of the American Institute of Nutrition advised that the kilocalorie should be replaced by the kilojoule kJ in scientific publications 30 , The Calorie probably entered U.
English because W. Atwater learned the term during studies in Germany, and not because it was defined in a newly translated physics text.
Justus Liebig did not mention the calorie as such in his book on animal chemistry 32 or his paper on energy production from foodstuffs However, he published J. Mayer's first scientific paper 34 , which defined a mechanical equivalent of heat. It was in the context of relating physical work against gravity Fallkraft or potential energy; Fig.
As translated by Lindsay 37 the quotation is: When substances endowed with considerable chemical affinity for each other combine chemically, much heat is developed during the process. The quantity of heat necessary to raise 1 kilogramme of water 1 degree is called a unit of heat, Calorie. Caloric equivalent of work done against gravity. Mayer's views became known due to his dispute with Joule for priority in the discovery of the caloric equivalent of physical work 37 , for which he was awarded the Copley medal in , 1 y after Joule.
Presently, it seems that an amateur has claim to the first definition of the Calorie in German science! Mayer may have learned of the Calorie because he studied in Paris and purchased a library that included French and German physics and chemistry texts of the period Despite this, Voit began using the g-calorie in lectures on human calorimetry in and stated that daily metabolism of 1 male subject was 2.
At that time, Pettenkofer and Voit 40 were using indirect calorimetry to study human and animal respiration and Voit was conducting nutritional balance studies It was this juxtaposition between measuring human energy output and the energy content of foods by bomb calorimetry that gave the German school impetus to define daily energy intake and output in terms of calories. By —5, Max Rubner had published papers using the g-calorie to define heats of combustion for food and heat produced in respiration studies 42 — In the same period, Henneberg and Stohmann were developing methods for the proximate analysis of livestock feeds at the Weende Experiment Station Stohmann initiated calorimetric work in and conferred with Rubner concerning experiments in which the energy content of sugars, fats, and egg white was measured in g-calories Note that different German scientists varied in using either the g-calorie or the Calorie.
The German school of physiology introduced proximate analysis and calorimetry to determine the least expensive sources of nutritionally balanced foods and animal feeds This approach appealed to the American Wilbur O. Atwater, who visited Voit's laboratory in —3 and conducted postdoctoral studies along with Rubner In their report on nutritive values of foods, Atwater and Woods 48 specifically credit the Weende method of proximate analysis including fuel analysis as developed by Henneberg and Stohmann Atwater returned to the US and gave a presentation on economic aspects of the protein and energy content of foods It is not evident why Atwater selected the Calorie rather than the g-calorie as used in publications from colleagues in Voit's laboratory.
The articles on nutrition were published the same year that the U. His interest in establishing a rational basis for food selection led to work on the proximate analysis of foods and their physiological energy value Graham Lusk also visited the Voit laboratory and set the tone for nutrition education in the United States with his text, The Science of Nutrition , which emphasized energetics James P.
Joule did not use the calorie as a unit of heat in his published papers until 29 , Calorimetric studies by Smith 53 measured energy usage in terms of the carbon dioxide formed in metabolism but did not refer to calories. Frankland's heat units were identical to g-calories 9 and he stated that his work measured calorific values of foods.
In , Fick and Wislicenus observed that protein metabolism accounted for only a minor part of the energy required by muscular exertion during a mountain climb They calculated the energy content of protein albumen in heat units that equal modern kcal. In the ensuing international discussion of the study, the kg-m was consistently used as a unit of energy or work rather than the calorie Fig.
Kleiber's book explained that energy expenditure can be estimated by multiplying men's body masses in kg times the vertical distance of the climb and adjusting for mechanical efficiency The usage of kg-m or ft-lbs as units of energy persisted until the joule was adopted as a standard for all energy.
From to , a committee of the British Association for Advancement of Science met concerning standards for electrical measurements. Among other tasks, the committee solicited international opinion concerning heat units. In , it defined the dyne and erg and recommended that the CGS be adopted Food can contain components such as fiber that will burn in a calorimeter but are not absorbed into the bloodstream and therefore do not contribute calories.
Because carbohydrates contain some fiber that is not digested and utilized by the body, the fiber component is usually subtracted from the total carbohydrate before calculating the calories. Thus the label on a 45 gram KitKat that contains 3 g of protein, 29 g of carbohydrate 22 grams of which are simple sugars and 12 g of fat would read Calories. Some interesting data emerges from such calculations. The calorie content of a doughnut, about Kcal is found to be close to that of a stick of dynamite.
The difference of course is that the energy from the dynamite is released instantly when ignited, while the doughnut releases its energy content in the body more slowly. The evils of overeating may not be felt at once, but sooner or later they are sure to appear perhaps in an excessive amount of fatty tissue, perhaps in general debility, perhaps in actual disease. While Atkinson and Atwater were advocating for dietary restrictions based on calorie contents, it took some time before the idea of calorie counting became a mainstay in American diets.
In , American physician, author and philanthropist, Lulu Hunt Peters changed the face of dieting for the next century. Seeking to write a diet book targeted towards American women, Peters latched onto the idea that calorie counting was an effective means of enacting healthy weight loss.
With this idea in mind, Peters got to work. Proving popular with her audience, namely middle-aged American women, Peters was encouraged to collect her writings into one neat volume, something she did in Fortunately for Peters, one book was all she needed. Interestingly for athletes and bodybuilders, Peters advice on gaining and losing weight will seem very familiar.
To calculate your basic caloric needs, she recommended multiplying your bodyweight by to find the magic number. If you needed to lose weight eat calories less and to gain weight eat calories more. Fun facts, aside, Peters was undoubtedly hugely influential in popularising calorie counting for the general public. A trend that began in the late s and continues to this very day.
What you will find is a strong emphasis on eating natural, unprocessed foods.
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