Lying exhausts the brain because it has to track fabrications, remember invented details, and avoid contradictions. The mental strain shows in how liars communicate, making deception spotable if you know what to watch for.
Lies are unnatural, even to a skilled liar, which boils back to this idea of how the brain consumes resources. The human brain wants to conserve resources. If it was up to your brain, your brain would tell the truth. But when someone is lying, their brain has to go into overdrive to reference previous lies, remember details that never actually happened, try to recall what was shared with you and what wasn't shared with you in the past, make an assessment, Of whether or not the lie they're about to tell will contradict something else that you might come in contact with in the near future. Just imagine how much energy that takes. So when you're trying to spot a liar, especially spot a liar in the moment, what you're looking for is the effort that goes into their communication.
