Eating Lettuce Three Times Worse For The Environment Than Bacon

According to a recent paper put out by scientists at Carnegie Mellon University, following the USDA dietary recommendations to consume more fruits, vegetables and seafood would consume nearly 40% more energy and 10% more water resources on average than it would take to eat the Standard American Diet (SAD).  While I don’t dispute the findings, I certainly think the media hype surrounding this paper is loaded up with a whole bunch of disingenuous nonsense.

Of course, it makes perfect sense that eating a diet of only lettuce would put out three times more greenhouse gas emissions than eating a diet of bacon if you calculate resources used per calorie.  A pound of bacon contains 2077 calories compared to a pound of lettuce which contains 63 calories.  So a person would have to eat 33 pounds of lettuce to match the calories in a pound of bacon.  Obviously that’s an absurdity.  No one would ever eat that much lettuce in one sitting, but people eating a pound of bacon in one sitting is a common occurrence.

Common sense tells us that a normal vegan diet, based primarily on whole grains, tubers and legumes for calories, would ended up using far fewer resources per calorie than the present SAD diet.  Just ask yourself what the cows are eating.  Ever wonder why cows are fed a diet primarily of soy and corn instead of the grass they were born to eat?  That’s because soy and corn are extremely calorie dense vegetables.  A pound of potatoes has 347 calories, averaging just 6 times less the caloric density of bacon.  A pound of corn has 388 calories and a pound of beans has 419 calories.  A pound of soy beans contains 558 calories.

If we make the assumption that beans or potatoes have roughly the same resource cost to produce as lettuce, we could compare them to bacon given the information we already have.  If lettuce is three times worse for the environment at 63 calories per pound, we would need a caloric density of (3 x 63) 189 calories per pound to break even with bacon.  With that assumption, it appears that beans or potatoes would produce twice as few emissions as bacon. My bet is that it’s actually closer to three or four times though, because beans and potatoes don’t have to be refrigerated and they take less water to grow.

The USDA guidelines suggest swapping fish for beef and loading up on green vegetables, fruits and whole grains.  Of course fish are going to be more resource intensive per calorie than beef, and of course green vegetables and fruits are going to be more resource intensive per calorie than chicken. However, that doesn’t mean eating a healthier diet is going to end up destroying the planet or consuming vastly more resources to produce.  Eating a common sense healthy diet does not involve subsisting on lettuce, apples and fish.

Humans were able to escape the equatorial rain forest regions because our brains evolved to the point where we were able to grow and harvest grains, legumes and tubers.  Being able to harness the power of fire to cook these normally inedible calorie dense foods is what took us out of the jungles. Before that, we had to stick to where uncooked food was plentiful, like our great ape cousins do today.

We presently produce enough calories in plants to feed a planet of 10 billion people.  Given that there are only 7 billion people on the planet, the majority share of those crops are being fed to livestock.  If we didn’t eat animals, we wouldn’t need to grow all that feed for livestock.  We could easily reduce our agricultural resource consumption in half by simply eliminating animal products from our diet.

Another common sense point that bears noting is that humans managed to produce enough food to feed themselves without the benefit of modern irrigation, tractors, harvesters, mills or other equipment for hundreds of thousands of years.  Do you think the slaves in Egypt were living off meat and lettuce?  What about the peasant farmers in early America?  They were all subsisting on grains, legumes and tubers.  Meat was predominantly eaten by kings, queens and the land owning class. Livestock was far too valuable to eat.  Those oxen were needed to plow the fields.  Very few resources are necessary to produce enough grains, legumes and tubers to feed everyone.  People have been doing it by hand as far back as historical records go.

Of course, I don’t believe in global warming, but the water and energy resources used to produce all that cattle feed are still very real threats to the health of our environment.  Deforestation, agricultural runoff and water depletion, not to mention the health consequences from saturated fat and cholesterol consumption, are very real problems with major impacts on human health, longevity and living standards. And don’t forget the moral argument.  You wouldn’t slaughter your dog and eat it, would you?

Rather than using the USDA guidelines (that are the product of agricultural lobbyists) as the basis for their research paper, these scientists should have used a bit of common sense and looked at the resources that would be needed to consume a healthy plant based diet.  Had they done that, the results would most assuredly have been the complete opposite of what they presently found.

Oh by the way, here’s a fun bit of trivia for you.  Did you know potatoes are a complete protein and vitamin source?   If you don’t wash them first, you can even get your daily dose of B12 from them. You could literally live on a diet of nothing but potatoes for years (people have actually done this).  In fact, potatoes are also the most filling food per calorie you can eat.  Not only that, potatoes are also low in fat and one of the highest sources of antioxidants you can find.  Oh, did I forget to mention they are also loaded with fiber? Some of the longest lived people on the planet eat a diet primarily consisting of sweet potatoes.  It’s almost a bit scary how good potatoes are for you. Perhaps potatoes are the food humans were born to eat….

  • StrangerThingsHappen

    Thanks for this. That ridiculous article is causing a lot of damage. I’ll respond with this as much as possible.

  • Thorsten Bredberg

    Reading this article is like watching a Michael Moore documentary, omitting important details: the diet of meat has made us humans more intelligent albeit in many cases more agressive. The cultures as described in the above article that were living mainly on a corn and maize diet have lost out to meat eating cultures. That should not really come as a surprise.

    • Actually if you look at the research, it was humans ability to cook starchy root vegetables and grains that allowed us to evolve. The brain runs entirely on glucose, which is very limited in meat. In fact, meat causes arteries in the brain to become atherosclerotic. In cultures like Japan, vast intellectual and industrial advancements were made with virtually no dairy and very little meat consumption. The Japanese didn’t start consuming large amounts of meat until after WWII.

      • Thorsten Bredberg

        The consumption of meat is exactly the difference in the diet that made us more more “human”. Your very example of comparing us with the great apes, who are all mainly herbivores, could be seen as even more evidence in favor of my side of the argument.
        Check out porotic hyperostosis in skulls that have been found belonging to infants that suffered under malnutrition linked to meat-poor diets.
        All soldiers of great armies, be it of Rome, Sparta, Persia or Mongolia, were meat eaters wherever the situation allowed it. The Roman soldiers were known to have herds of cattle, sheep and goats to supplement their diet, which yes, mainly consisted of beans and lentils, but definitely precedes the era of the industrial revolution. And the last time I checked, Rome belonged to the West. Check out the diet of British soldiers in the 1800s, not much changed when compared to the Spartan diet: stew, meat pies and broth.
        Now, a solid point could be made and has been made, that these meat consuming armies were that much more aggressive and successful (think Vikings) mainly because of their diet containing meat.
        And: the Japanese always had a diet rich in fish and organ meats, before and after WW2.