This article originally appeared in the Winter 2019 issue of Tufts Nutrition Medicine.

1819 First recorded use of “calorie” to define a unit of heat, in lectures by chemical engineer Nicholas Clement in Paris.

1842 German J.R. Mayer defines “calorie” as the quantity of heat necessary to raise one kilogram of water one degree Celsius, the concept still used on U.S. food labels.
1887 Chemist W.O. Atwater brings the term to the U.S., promoting efficient use of calories to ensure workers are fed in an economical manner. (He estimates an average daily intake of 2,300 calories for women,
and 2,830 for men.)

1917 Starting this year, and continuing through the end of World War I, the Food Administration urges Americans to conserve food. Eating more calories than necessary, it warns, will undermine the war effort. Some restaurants list calorie counts on menus to show their patriotism.

1918 Lulu Hunt Peters, a doctor in Hollywood, California, publishes her best-selling diet book, Diet and Health, which promotes counting calories to lose weight.

1941 The Food and Nutrition Board of the National Academy of Science prepares the first Recommended Daily Allowances, listing recommended intakes for calories, protein, and a handful of vitamins and minerals.

1952 The first no-calorie soda—appropriately named No-Cal—is marketed by the Kirsch beverage company of New York.

1981 Nestle introduces Lean Cuisine, a line of ten frozen dinners with less than three hundred calories. High demand causes the company to have to ration distribution to retailers.

1990 Calorie and other nutrition information appears on all packaged foods, a mandate of the federal Nutrition Labeling and Education Act.

2015 To maintain weight, the Dietary Guidelines for Americans recommends 1,600 to 2,400 calories per day for adult women, and 2,000 to 3,000 calories per day for adult men.

2018 Under a provision of the Affordable Care Act, chain restaurants are required to post calorie counts.

Helene Ragovin

Helene Ragovin, senior writer at Tufts and editor of Tufts Dental Medicine, can be reached at