View full lesson: http://ed.ted.com/lessons/what-is-a-calorie-emma-bryce We hear about calories all the time: How many calories are in this cookie? How many are burned by doing 100 jumping jacks, or long-distance running, or fidgeting? But what is a calorie, really? And how many of them do we actually need? Emma Bryce explains how a few different factors should go into determining the recommended amount for each person. Lesson by Emma Bryce, animation by Qa'ed Mai.