We’re not joking here. While it may seem weird, running a microwave with nothing in it can be potentially dangerous. The radio waves that are emitted when a microwave runs with nothing in it are absorbed into the microwave itself.
The microwave is not meant to run without anything inside of it and it is not able to handle all of the waves. This can lead to the machine self-destructing or potentially starting a fire.
Staying fit is certainly a commitment. Besides doing the physical training, there are some other factors to consider, like nutrition