On what basis do you claim that an individual eats a fixed amount of food?
If you're worried about how artificially elevated CO2 levels affect agricultural products, then you should start taking issue with commercial greenhouses, which regularly pump CO2 in to increase yields. This is a common practice, and only now is it being viewed as something bad or strange because it's not convenient for the climate change narrative that presents industrial emission of CO2 as the apex threat that requires government-enforced collective action to solve.
If you're worried about how artificially elevated CO2 levels affect agricultural products, then you should start taking issue with commercial greenhouses, which regularly pump CO2 in to increase yields. This is a common practice, and only now is it being viewed as something bad or strange because it's not convenient for the climate change narrative that presents industrial emission of CO2 as the apex threat that requires government-enforced collective action to solve.