You Can Instantly Tell Someone Is A Liar If They Do These 5 Weird Things With Their Body, Says FBI Agent

An ex-FBI agent says liars give themselves away without realizing it.

Last updated on Oct 08, 2025

Liar does weird things with body. Amin Naderloei | Unsplash
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While plenty of relationships are built on trust, sometimes people tell lies in an effort to get what they want. Sure, it’d be easier to spot if all liars turned into Pinocchio at the end of the day, but sadly, that isn’t the case.

In a University of Massachusetts study, researchers discovered 60% of adults can’t have a ten-minute conversation without lying, averaging three lies per every 10-minute session. Those numbers are not only shocking, but seemingly worse for those whose parents were compulsively lying growing up. According to another study, by the age of four, 90% of children have grasped this sneaky distrustful concept, and it only gets worse from there.

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Do you know you know how to spot a liar? Though we can detect lies about 54% of the time accurately (coin flip, anyone?), we think it's valuable to know a few more reliable ways to catch a liar.

You can instantly tell someone is a liar if they do these 5 weird things with their body, says FBI agent:

1. Skin picking, nail biting, etc.

Joe Navarro, founding member of the FBI’s Behavioral Analysis Unit and author of the international bestseller, What Every Body is Saying: An Ex-FBI Agent's Guide To Speed-Reading People, advises paying close attention to body language since there is never one dead giveaway. Instead, liars illustrate multiple behaviors indicative of psychological discomfort, anxiety, or distress when asked a question. 

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Research also suggests that because the muscles in our face are not under complete conscious control, certain muscles will betray the liar, especially in highly emotional situations.

RELATED: 7 Subtle Ways To Detect Someone Is Telling A Bald-Faced Lie, According To Longtime Detective

2. Purse their lips

woman who is telling a lie as she purses her lips stockfour / Shutterstock

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When our lips are pursed, it often illustrates information trying to be held in. Indicative of extreme anxiety, withholding aggression or anger, our mouths say a lot when we’re nervous. 

As they become dry, liars find themselves licking their lips and swallowing more than usual as they struggle to find the appropriate words.

RELATED: Psychology Says People Who Are Good At Reading People Always Use These 7 Tricks

3. Hide their thumbs

When someone is lying, they will begin to fidget — a lot like a child sharing tall tales. Signs of insecurity include touching the nose and eyes, turning the body away, turning the feet toward an exit, and lowering or hiding thumbs. 

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Sometimes liars might even unconsciously place objects between the two of you in an effort to move away.

4. Avoid any eye contact

man who is a liar as he breaks eye contact Studio Romantic / Shutterstock

While breaking eye contact is not a real indicator of lying, liars will often avoid looking people in the eye. However, if they maintain an abnormal amount of eye contact, they’re working harder to maintain the lie. Conversely, if the person has darting eyes, it’s a sure-fire signal of distress and subconsciously looking for an escape route.

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RELATED: How To Read A Person's Face And Easily Predict Their Behavior, According To Master Face Reader

5. Their sentences seem to never end

A Harvard University study discovered that people who lie tend to use a lot more language than those who tell the truth. This is because of a need to convince the listener of what is said, rather than telling them directly. Researchers call this the “Pinocchio Effect”—the length of a sentence grows with a lie.

In addition to taking a guarded tone and perhaps telling their story in a strict chronological order, liars won’t use contractions in their denials, but they will either avoid or confuse pronouns. While giving very specific negations (“I never cheated on anyone in my entire life”), liars also tend to overemphasize their truthfulness with qualifying language like “Honestly,” “To tell you the truth,” or “I swear.”

In addition (unless professional actors), liars will usually stutter or hesitate when they speak, and answer questions with a question, while keeping things very brief. In the case of online relationships, Brigham Young University discovered an easy way to spot dishonesty in digital messaging is — wait for it — the pause right before a lie is sent. 

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RELATED: 10 Lies Your Guy Is Telling You — And What He's Hiding

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