Fat, joules and iPhones oh my!

So my iPhone 5 has a 5.45Wh battery, 1 watt is 1 joule a second. So the iPhone 5 battery has a potential of 19,620 joules (new)... a kcal (big C calorie, what you see on a food label) is 4184 joules. A pound of fat has around 17,080 joules based on my math (joules per gram of fat sourced from google search, 37.656J per gram of fat)... Quick, convince my body to grow an electrical outlet!!!