Most veggies are mostly water by weight/volume so it wouldn't be a good deal. They also have very little actual calories. What you want is actually cereal. The

Most veggies are mostly water by weight/volume so it wouldn't be a good deal. They also have very little actual calories. What you want is actually cereal. They probably absorb a bit let CO2 than trees but at least you can eat them so that's more useful.