Does anything inside the human body radiate energy?
Your body consumes food, a source of energy, and then burns it up to produce some useful work and quite a lot of heat. Also, it produces heat just for the purposes of maintaining a constant body temperature. Both of these sources of heat cause your body to radiate thermal energy, which can be detected with infrared sensors. A recent experiment also shows that humans are very, very slightly bio-luminescent on certain parts of the face, so this is another sort of radiation (but a very weak one). One other radiation source comes to mind… the nervous system of the human body (and all animals that I’m aware of) uses electrochemical signals to relay sensory information as well as for brain function. These electrical signals are fairly weak, and would be difficult to detect more than a few inches away, but they do radiate in the very low end of the electromagnetic radio wave spectrum.