It's stupid to make categorical statement such as 'The only time eating beef makes sense…' because you're making an absolute out of something with so many nuances. However, you seem to be talking about energy efficiency of the production of the food, while I'm talking about the efficiency of eating it.

I don't disagree that cattle may be less efficient to produce than vegetables and grains. However, there's still many reasons to produce cattle, as I pointed out. The by-products and higher energy density of the food for one, and many others, such as variety in your diet. There is a reason people do the things that they do. If we were optimizing everything on one axis, if we were solely concerned with the efficiency of production, we'd live pretty sorry, unfulfilling, colorless and utterly boring lives. We would not take the time to weave patterns into our fabrics, we would not put decorative architectural touches on our houses, and we would not style our hair.

I do not want to live in a world where people are made to feel guilty about eating meat because it's less efficient to produce. I do not want to be an efficiency-bot automaton. I really feel like the deafening push to induce guilt for not reducing your carbon footprint is the new puritanism, in a bad way. If we're going to feel bad about flying on airplanes to go on vacation, we all might as well take the idea to its logical conclusion and deny ourselves every modern convenience of the last 500 years: return to subsistence farming in self-built huts with no electricity. Short of doing that, no token self-denial is going to realistically make an impact.

FYI: people in the rest of the world do eat the way in you describe. i.e., a vegetable-and-grain based diet with a little bit of meat now and again.

The simple fact of the matter is that most of the rest of the world is poor, and we are rich. They eat that way because they have no choice, not because there's something inherently better about it. Not to say, though, that there isn't something better about it — like I pointed out, I eat mostly vegetables and beans. But simply the fact that everyone does it doesn't make it good a good idea in and of itself.

Btw, 1 lb of beef takes 7 lb of corn to produce (cows in America are primarily fed corn). Are you seriously claiming that eating the cow instead of the corn is more efficient?

I made no such claim at all in my post. I simply pointed out that the disparity is not so great as people like to claim. However, now that you've brought it up, I would indeed argue that eating beef instead of corn is more efficient. It all depends on what you define as 'efficient'.

Do you know how long it takes to shovel a dinner plate full of vegetables down your throat four times a day? Like, two hours a day. Think about the fact that beef has twenty times the calories of tomatoes — you have to eat twenty times the number of tomatoes to get the same number of calories. That is a lot! A significant chunk of your day becomes devoted to eating. That's not efficient. That's time I could be spending doing other more important and useful things — like writing software to automate other mindless tasks, making us even more efficient. Of course, I eat that way for other reasons, but I would never argue that it's efficient.

Meat is kind of like the food equivalent of fossil fuels. Oil is the super-concentrated end product of millions of years of sunlight shining down on plants and algae. We can then burn that concentrated end product to power a loom to weave fabric really fast, rather than doing it slow by hand. Similarly, meat is the end product of months of a cow sitting in a field chewing grass and in a barn eating corn. We don't need to sit around eating massive amounts of vegetables because the cow already did that for us.

Simply put, the 7 pounds of corn may not be efficient when you look at it with tunnel vision from the perspective of a single variable (land use), but it very certainly may be efficient when you look at it from others. So don't pretend it's so simple.

I'm not arguing against vegetarianism or eating vegetables, I'm simply saying there are also valid reasons to produce meat. I like everything in moderation.