Some news in the world of sustainable food: Chipotle is responding to beef supply shortages by considering looser standards. Instead of aiming to avoid all beef treated with antibiotics, the burrito chain and sustainable ag advocate may start accepting cows treated for illness, while still avoiding those given antibiotics as a matter of routine.

It's a defensible place to draw the line. The problem with livestock antibiotics is primarily about overuse, not any use at all.  As Laura Rogers argues, American beef would be far safer if the standard Chipotle is considering were the actual regulatory standard for everyone.

Not that the chain can be expected to follow this standard strictly. They don't follow their current one strictly now. Instead, they get as much of the good beef as they can—and when the supply runs out, they fill out their inventory with other stuff.

In other words: Chipotle's meat standards are not the bottom line. Sales are, and they're growing quickly. And as impressive a company as Chipotle is, it's hard to take their pro-sustainability stance seriously when their spokespeople say things like, "Every year we need 20 to 25 percent more of everything than we did the year before, and the [naturally raised] beef supply isn't keeping up as well."

I don't care if your cows eat strictly lawn mower clippings while jogging in enormous electricity-generating hamster wheels. "More beef" is not a formula for a sustainable future. Yes, we should support better livestock practices, and switching from Burger King to Chipotle may help. But all beef production is extremely resource intensive, so the very notion of sustainable beef requires eating far less of it. And I'd be a lot more impressed with Chipotle if they did more to promote this idea.

I get that there's very little—not even a limited supply of a crucial ingredient—that will make a publicly traded company actively choose not to grow. But Chipotle could use its menu and its advocacy efforts to promote a less meat-intensive diet. For instance:

• Right now, Chipotle's veggie burrito is the same price as the chicken one and only a couple dimes less than the red-meat options. But the veggie burrito alone comes with free guacamole—which, of course, not everyone likes. Why not make the veggie burrito much cheaper than the others, and scratch the free guac? Then push this menu item hard as an affordable, more healthful, extra-eco-friendly option. No one's going to mistake you for a judgmental hippy when the meat's still right there on the menu, too.

• And/or, explain to customers that the supply issues require a tough choice, and here's the choice we've made: We're putting less meat on each burrito (and more other stuff). Include an extra meat helping for an extra charge. Educate customers about the value (again: price, health, planet) of eating less meat, even though they'd have to be crazy to go off the stuff altogether cause it's so delicious when we adobo-marinate it etc., etc. (Unlike a burger, a burrito makes such a move relatively easy and nonthreatening.)

• Introduce a smaller burrito option. My favorite Chipotle burrito—which includes no sour cream and no double-anything—has more than 1,000 calories. Sure, I could get it without the tortilla, cheese, or guacamole, but I don't want a less tasty burrito. I want a delicious one that's small enough to eat for lunch as part of a reasonable, sustainable diet.

Chipotle's known for combining the expectations of fast food—fast, simple, consistent, indulgent—with higher-quality ingredients and attention to sustainability issues. It's frustrating that they treat their menu like such an absolute: What they do is sell enormous burritos, with a few similarly priced options, two of them beef-centered. But they're a brilliantly creative company. If they care so much about sustainability, why not use their position to actively promote a lower-meat diet?