This. The actual rule is:
A character needs one pound of food per day and can make food last longer by subsisting on half rations. Eating half a pound of food in a day counts as half a day without food.
Now, I'm not defending the way it was written - it seems designed to mislead because the implication to most native English speakers is that they are equating half rations to half pounds. But given that the sentence does not exist in isolation (the book says a ration is 2 lbs and that you need 1 lb per day), if we look at it carefully we can see they are not saying that a half ration counts as half a day without food.
The interpretation we're left with is that rations are 2 lbs, you ought to eat the whole thing, you can eat 1 lb but the negative effects are not sufficient to affect the game, and if you eat 1/2 lb it starts to have game effects.
Again, poor wording but not actually contradictory.