Green’s Dictionary of Slang

1. scars on one’s wrist denoting a failed or insufficiently committed suicide attempt.

1972		B. Rodgers Queens’ Vernacular 163: ‘Hesitation marks’ = scars on wrists of attempted suicides. Gaining weight is enough to make some queens suicidal, so, instead of saying ‘putting on a few pounds, dear?’ one may subtly dig the knife deeper with a ‘putting on a few hesitation marks, precious?’.
2001		Court TV 🌐 The medical examiner who told detectives about the marks on Katie’s thigh changes his theory. He now believes the indentations might be self-inflicted ‘hesitation’ marks – created by Katie as she got up the nerve to stab herself.

2. (US gay) excessive weight [the idea that extra weight is enough to make gay men suicidal].

1972

see sense 1.