Does the history of food energy units suggest a solution to "Calorie confusion"?

The Calorie (kcal) of present U.S. food labels is similar to the original French definition of 1825. The original published source (now available on the internet) defined the Calorie as the quantity of heat needed to raise the temperature of 1 kg of water from 0 to 1°C. The Calorie originated in studies concerning fuel efficiency for the steam engine and had entered dictionaries by 1840. It was the only energy unit in English dictionaries available to W.O. Atwater in 1887 for his popular articles on food and tables of food composition. Therefore, the Calorie became the preferred unit of potential energy in nutrition science and dietetics, but was displaced when the joule, g-calorie and kcal were introduced. This article will explain the context in which Nicolas Clément-Desormes defined the original Calorie and the depth of his collaboration with Sadi Carnot. It will review the history of other energy units and show how the original Calorie was usurped during the period of international standardization. As a result, no form of the Calorie is recognized as an SI unit. It is untenable to continue to use the same word for different thermal units (g-calorie and kg-calorie) and to use different words for the same unit (Calorie and kcal). The only valid use of the Calorie is in common speech and public nutrition education. To avoid ongoing confusion, scientists should complete the transition to the joule and cease using kcal in any context

A prospective analysis of dietary energy density at age 5 and 7 years and fatness at 9 years among UK children.

OBJECTIVE: To analyse whether high dietary energy density (DED) is associated with increased fat mass and risk of excess adiposity in free-living children. DESIGN: Longitudinal, observational cohort study. SUBJECTS: Six hundred and eighty-two healthy children from the Avon Longitudinal Study of Parents and Children. MEASUREMENTS: Diet was assessed at age 5 and 7 years using 3-day diet diaries, and DED (kJ g(-1)) was calculated excluding drinks. Fat mass was estimated at age 9 years using Dual-Energy X-ray Absorptiometry. To adjust for body size, fat mass index (FMI) was calculated by dividing fat mass (kg) by height (m(5.8)). Excess adiposity was defined as the top quintile of logFMI. RESULTS: Mean DED at age 5 years was higher among children with excess adiposity at age 9 years compared to the remaining sample (8.8+/-0.16 vs 8.5+/-0.07 kJ g(-1)), but there was no evidence of an association with excess adiposity at age 9 years (odds ratio (OR)=1.14, 95% confidence interval (CI) 0.90-1.44) after controlling for potential confounders. Mean DED at age 7 years was higher among children with excess adiposity compared to the remaining sample (9.1+/-0.12 vs 8.8+/-0.06 kJ g(-1)) and a 1 kJ g(-1) rise in DED increased the odds of excess adiposity at 9 years by 36% (OR=1.36, 95% CI 1.09-1.69) after controlling for potential confounders. CONCLUSION: Higher DED at age 7 years, but not age 5 years, is a risk factor for excess adiposity at age 9 years, perhaps reflecting deterioration in the ability to compensate for extra calories in an energy-dense diet. DED tracks strongly from age 5 to 7 years suggesting intervention to alter dietary habits need to commence at younger ages to prevent the formation of preferences for energy dense foods