The meat is whole abdomen of the radroach. Since radroaches appear less frequently Fallout: New Vegas than in Fallout 3, radroach meat is increasingly difficult to find. Radroach meat restores a small amount of hit points, and gives an unreasonably high dose of radiation. Consuming it also gives a -1 penalty to Strength. Needless to say, it may be better to avoid this snack altogether than try to consume it.
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