The two are Arli Chontei, in the 56-kilogram category, and Farkhad Kharki, in the 62-kilogram class.
International Weightlifting Federation spokeswoman Aniko Nemeth-Mora said Thursday that Kazakhstan is citing medical reasons. However, Kazakh weightlifting official Mendikhan Tapsiruly told AP that "this is most likely to do with the fact they were granted citizenship recently."
Two other lifters in Kazakhstan's team were recruited from China, while one switched nationalities from Russia.
It wasn't immediately clear Thursday who would replace Chontei and Kharki for the weekend competitions.