Amount of energy required to raise one-thousand of water by one degree .

Contrast "Calorie" (with a big "C") with "" with a small "c" where the latter is 1000-fold smaller than the former.

From "Everything you know about calories is wrong" ("Digestion is too messy a process to accurately convey in neat numbers. The counts on can differ wildly from the calories you actually extract, for many reasons") :

At one particularly strange moment in my career, I found myself picking through giant conical piles of produced by —those goofy to the . I was trying to figure out how often seeds pass all the away through the emu intact enough to . My colleagues and I planted thousands of collected seeds and waited. Eventually, little grew. ¶ Clearly, the plants that emus eat have evolved seeds that can digestion relatively unscathed. Whereas the birds want to get as many calories from fruits as possible—including from the seeds—the plants are invested in protecting their progeny. Although it did not occur to me at the time, I realized that humans, too, engage in a kind of with the food we eat, a battle in which we are measuring the spoils—calories—all wrong.