A calorie is not always a calorie.
I learned many years ago that a calorie if the amount of heat required to raise the temperature of one gram of water one degree centigrade at one atmosphere of pressure.
We often see listings of how many calories some food contains. Well that's all a big lie. Dietitians - and industry, and the general public (by default) - use the kilocalory (1,000 of the calories I described above). When they say that a burger contains one thousand calories, it actually contains one million calories. The kilo- prefix is dropped, even though that is the metric they are using.
Have you learned anything today?