*** #FoodNerdTrivia ***

Q: What energy is equivalent to 4.1868 joules, the heat energy needed to raise the temperature of 1 gram of H2O by 1 K (or, 1°C)?

Answer: calorie, Small calorie, or g-calorie, unit of energy equivalent to the heat energy needed to raise the temperature of 1 gram of water by 1 °C (now often defined as equal to 4.1868 joules). kJ ≈ 0.239 kcal.

Calorie vs. calorie
The big calorie (1 Cal) indicates the amount of energy needed to raise the temperature of 1 kg of water by 1 degree Celsius (1°C).= 1 kcal  1 kcal = 1000 calories = 1 Calorie

The small calorie (1 cal) – shows the same amount for one 1 gram instead of 1 kilogram.

A Kilocalorie is a common unit used to express food energy, namely the specific energy (energy / mass) of metabolizing different types of food. Fat (triglyceride lipids) contains 9 kcal/g, carbohydrates (sugar and starch) and protein contain ~ 4 kcal/g.[29] Alcohol in food contains ~ 7 kcal/g.

History of the Caloric Value
W.O. Atwater utilized the “Calorie” in early 1887 publications on his theory of the nutritional value of food. It was based on experiments with a human subject eating a controlled and limited diet in a small room while being monitored. Nutrition sciences have come a long way. History of the Calorie in Nutrition – The Journal of Nutrition: https://jn.nutrition.org/article/S0022-3166(22)08554-6/fulltext

Calories on the Nutrition Facts Label | FDA
https://www.fda.gov/food/nutrition-facts-label/calories-nutrition-facts-label
Title 21, section 104.20, part d of the Code of Federal Regulations[1]:

“(1) A normal serving of the food contains at least 40 kilocalories that is, 2 percent of a daily intake of 2,000 kilocalories; (3) The food contains all of the following nutrients per 100 calories based on 2,000 calorie total intake as a daily standard…”

Easy, right?
We appreciate all the nutrition scientists out there doing all these conversions.