Leviticus 26:29 is a prophesy that was fulfilled due to extreme hunger during the famines at the siege of Samaria by the Syrians (Deuteronomy 28:53-57) and also at the siege of Jerusalem by the Chaldæans (2Kings 6:28-29).

See also :
Lamentations 4:10
Jeremiah 19:9
Ezekiel 5:10
Zechariah 11:9