Boeing 747s burn kerosene, about 5,000 gallons of the stuff every hour. Each gallon of jet fuel contains 34 million calories, so the big silver bird is consuming fuel at the rate of 170 billion calories per hour. A typical 747 weighs 750,000 pounds (including roughly 250,000 pounds of fuel) so it burns 226,667 calories per hour per pound.
Hummingbirds burn fat. Experiments with hummingbirds in metabolic chambers showed that the little colorful birds consume fuel at the rate of about 1200 calories per hour. A typical hummingbird weighs not much more than a penny, about 4.5 grams of which 2 g is fat. That's about .01 pounds, so a hummingbird burns about 120,000 calories per hour per pound—about half that of a 747. Humans burn about 5
If that sounds like a lot, keep in mind that thermochemical calories and food calories are different. Food Calories (big 'C'), also known as kilocalories, are 1000 times bigger than engineer's calories (small 'c').