Index 
Our species seems to be the only one that uses more calories than it takes to keep our bodies alive. For humans this is about 20 calories per kilogram, or for an average 120 pound (~ 50 kg) person, about 1000 calories. I note that these are dietary or "food" calories which correspond to 1000 calories in physics calculations such as those below. Thus it appears in the US we use about 200 times what it takes to keep us alive (me only 100 times, because I weigh about 100 kg, so eat about 2000 "food" calories). The world in total uses about one fourth as much as the US, noting that many countries such as India use far less than the world average, which of course includes European, American, and Japanese economic powerhouses. So an Indian my weight uses only about 7 or 8 times his energy "needs", still a lot compared to other mammals. Noble Beasts Indeed Table 1. Calories used by each of us per day: (compare to food calories required to live, about 2000 calories or less) | ||||||||||||||||||||||||||||||||||||||||
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Though there are nearly infinite ways to get from annual energy use data to food calories per person, I started with Wikipedia "World Energy Consumption" which listed annual world energy use in petawatthours among others. I converted this data to food calories, which are of interest here. I use the following petawatthour data to first calculate total annual energy in terawatts, TW. Table 2. Energy use in the World, USA and India, 1990 and 2008 | ||||||||||||||||||||||||||||||||||||||||
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columns 2-7 in petawatthours from columns,8-10 in terawatts, calculated from columns 5-7 To proceed to food calories per person, I assumed the following populations in millions, also from Wikipedia. | ||||||||||||||||||||||||||||||||||||||||
which I used in conversions from TW to calories per person |