Everything radiates infra-red radiation. The amount we radiate depends how hot we are. The hotter we are the more we radiate.

Look up the Stefan–Boltzmann law which describes how much power we radiate - we radiate pretty much like Black Bodies in the Infra-red

How human body is acting as electro magnetic wave generator in terms of electronics and also as antenna

Wikipedia says " Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation."

Look up the rest of the article on Thermal radiation.

Thanks