You're right, I should have provided a source. In the end, it's basic physics, really. If you make a plant, and feed that plant to an animal, and then eat that

You're right, I should have provided a source. In the end, it's basic physics, really. If you make a plant, and feed that plant to an animal, and then eat that animal, your caloric conversion rate will always be lower than eating the plant directly lest you violate the laws of thermodynamics. But, here's a really good summary by Our World in Data going into more detail: https://ourworldindata.org/land-use-diets https://ourworldindata.org/land-use-diets