A calorie is a calorie

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"A calorie is a calorie" is a tautology used to convey the speaker's conviction that the concept of the "calorie" is in fact a sufficient way to describe energy content of food.

The tautological phrase means that regardless of the form of food calorie a person consumes (whether a carbohydrate, protein or fat calorie) the energetic value of such a calorie, is identical to any other. One dietary calorie contains 4,184 joules of energy. With this knowledge, it is easy to assume that all calories have equal value.[1]

However, good human nutrition measures foods for other values than just energy in calories.{{Cite web|url=Richard_D[citation needed]

Weightloss pyramid.svg


In 1878, German nutritionist Max Rubner crafted what he called the "isodynamic law".[2] The law claims that the basis of nutrition is the exchange of energy,[3] and was applied to the study of obesity in the early 1900s by Carl von Noorden. Von Noorden had two theories about what caused people to develop obesity. The first simply avowed Rubner's notion that "a calorie is a calorie". The second theorized that obesity development depends on how the body partitions calories for either use or storage.[2] Since 1925, a calorie has been defined in terms of the joule. The definition of a calorie changed in 1948, which became one calorie is equal to approximately 4,2 joules.[4]

The related concept of "calorie in, calorie out" is contested[5] and despite having become a commonly held and frequently referenced belief in nutritionism, the implications associated with "a calorie is a calorie" are still being debated.[6][7][8] The wisdom and effects of skipping meals in an attempt to limit caloric intake is also still largely debated.[9][10][11]

Calorie counting[edit]

Calorie amounts found on food labels are based on the Atwater system.[12] The accuracy of the system is disputed, despite no real proposed alternatives. For example, a 2012 study by a USDA scientist concluded that the measured energy content of a sample of almonds was 32% lower than the estimated Atwater value.[13] Furthermore, it is known that some calories are lost in waste, without ever having been chemically converted or stored. The driving mechanism behind caloric intake is absorption, which occurs largely in the small intestine and distributes nutrients to the circulatory and lymphatic capillaries by means of osmosis, diffusion and active transport. Fat, in particular is emulsified by bile produced by the liver and stored in the gallbladder where it is released to the small intestine via the bile duct. A relatively lesser amount of absorption, composed primarily of water, occurs in the large intestine.


Wake Forest University Research[edit]

In 2007, a group of Wake Forest University researchers published a report from a six-year longitudinal study in which they fed two groups of monkeys the same number of calories and dietary levels of fat, with the only difference being that one group was fed foods higher in trans fat. The high trans fat group gained 30% more belly fat compared to their lower trans fat counterparts.[14] The researchers concluded that the type of calories consumed do affect body weight.[7]

The physical activities of the monkeys were not taken into account during this study.[citation needed] The sample size was 38.[citation needed]

Harvard University Research[edit]

In 2011, a group of Harvard University researchers published the results of a study in the New England Journal of Medicine that followed 120,877 highly educated men and women over a period of 12 to 20 years. The study focused on factors that influence weight gain including diet, exercise, sleep, smoking, alcohol intake and television watching. Participants began the study as healthy adults. Every two years, they would complete detailed questionnaires about their eating and other habits. The results found that an array of factors influenced the fluctuation of a person's weight. The average participant gained about one pound per year. Among the results of the study, it was found that the types of foods people ate had a larger effect on weight gain than physical activity.[15] According to the researchers "Consumption of processed foods that are higher in starches, refined grains, fats, and sugars can increase weight gain." and "These results suggest that future policies and research efforts to prevent obesity should consider food structure and processing as potentially relevant dietary metrics."[16] The lead author of the study concluded in an interview that trying to count calories, in an effort to lose weight, would be futile unless one is examining the kinds of calories being consumed.[15]


One dietary Calorie contains 4184 joules of energy. The human body is a highly complex biochemical system that undergoes processes which regulate energy balance. The metabolic pathways for protein are less efficient than the metabolic pathways for carbohydrates and fat.[citation needed] Protein contains four calories per gram, although a large part of the calories are lost as heat when metabolised by the body.[1]

It may be easy to consume 500 calories worth of ice cream or chocolate in one sitting, although it may be difficult to eat 500 calories of eggs or carrot in one sitting.[1]

Boston Children's Hospital Clinical Trial[edit]

In 2012, the Journal of the American Medical Association published the results of a clinical trial performed by a group of researchers that investigated whether dietary composition affected weight loss.[17] The study tracked 21 individuals. The individuals first lost at least 12.5% of their body weight, and were then placed on one of three different dietary regimens:

  1. A diet high in protein and fat, but with fewer carbohydrates
  2. A diet low in fat, emphasizing whole grains, fruit and vegetables
  3. A diet with a low glycemic index, focusing on the type of carbohydrates consumed

The results showed that the first group burned the most calories, but also displayed increased markers of stress and inflammation in the body, which can lead to cardiovascular disease, among other health problems. The second group burned fewer calories than the other two groups, and also displayed certain metabolic indicators that typically precede weight gain. The third group burned a reasonable number of calories, but notably did not display increased markers of disease-causing stress. The researchers concluded that the type of calories consumed does affect the number of calories burned by an individual. This conclusion is in direct contrast to what the commonly held belief implies.[2][7][8]

See also[edit]


  1. ^ a b c "A calorie is NOT a calorie". Authority Nutrition. 2016.
  2. ^ a b c Taubes, Gary (30 June 2012). "What Really Makes Us Fat". The New York Times. Retrieved 25 April 2013.
  3. ^ The Biochmeical Journal, Volume 16. Biochemical Society. 1922. p. 751.
  4. ^ Andrews, A. (2015). "Calorie". Black's Veterinary Dictionary.
  5. ^ Taubes, Gary (24 September 2007). "The Scientist and the Stairmaster". New York Magazine. Retrieved 8 May 2013.
  6. ^ Sass, Cynthia (7 February 2013). "Why Calorie Counts are Wrong: 6 Diet Myths, Busted". health.com. Retrieved 25 April 2013.
  7. ^ a b c Gann, Carrie. "For Calories, It's All About Quality Over Quantity, Harvard Study Says". ABC News. Retrieved 25 April 2013.
  8. ^ a b Nesheim, Malden. "Is a Calorie a Calorie?". NOVA. PBS. Retrieved 25 April 2013.
  9. ^ Zeratsky, Katherine. "Breakfast: How does it help weight control?". Mayo Clinic. Retrieved 28 April 2013.
  10. ^ "Breakfast is 'most important meal'". BBC News. 7 March 2003. Retrieved 28 April 2013.
  11. ^ Reinagel, Monica. "Is Skipping Breakfast Bad For You?". Nutrition Diva. Retrieved 28 April 2013.
  12. ^ Maynard, Leonard (1944). "The Atwater system of calculating the caloric value of diets". 440 - 443.
  13. ^ Nesheim, Nestle, Malden, Marion (2012-09-20). "Is a Calorie a Calorie?". PBS NOVA. Retrieved 2013-05-08.
  14. ^ Kavanagh, Kylie; Kate L. Jones; Janet Sawyer; Kathryn Kelley; J. Jeffrey Carr; Janice D. Wagner; Lawrence L. Rudel (July 2007). "Trans Fat Diet Induces Abdominal Obesity and Changes in Insulin Sensitivity in Monkeys". Obesity. 15 (7): 1675–1684. doi:10.1038/oby.2007.200. PMID 17636085.
  15. ^ a b Brody, Jane E. (18 June 2011). "Still County Calories? Your Weight-Loss Plan May Be Outdated". The New York Times. Retrieved 7 May 2013.
  16. ^ Mozaffarian, Dariush; Tao Hao; Eric B. Rimm; Walter C. Willett; Frank B. Hu (20 June 2011). "Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men". The New England Journal of Medicine. 364 (25): 2392–404. doi:10.1056/NEJMoa1014296. PMC 3151731. PMID 21696306. Retrieved 7 May 2013.
  17. ^ Ebbeling, Cara; anis F. Swain; Henry A. Feldman; William W. Wong; David L. Hachey; Erica Garcia-Lago; David S. Ludwig (21 June 2012). "Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance". The Journal of the American Medical Association. 307 (23): 2627–2634. doi:10.1001/jama.2012.6607. PMC 3564212. PMID 22735432. Retrieved 25 April 2013.