Fist clenching can be subtle and show hidden insecurity and hostility.
Holding the fists clenched and holding a full arm cross shows hostility, defensiveness and also readiness to attack. It can also be accompanied by a red face, clenched teeth, lowered eyebrows, a forward thrust of the lips or an angry expression. These accompanying signals show that physical aggression is imminent and likely, and ignoring them can be a huge mistake. In business and other context were violence is strictly forbidden we see an abbreviation of the hostile cues listed above. Here we see a more subtly form with the fists clenched tightly and the arms folded across the chest, usually while seated. Other times the dominant hand will make a fist with the other hand clasping the wrist. This is a mental way for the person to ‘hold themselves back.’ In other words, when we lack the right to truly express ourselves due to social norms, we “hold” back our negativity.