lettuce watered
Vegetables tend to have a low calorie count in comparison to meatsReuters

Meat eaters have had a hard year. The WHO officially called red meat cancerous and even the well-known protein fan, Arnold Schwarzenegger, said that people need to eat less meat to stop the coming environmental disaster. No wonder everywhere jumped on a study that said lettuce is worse for the environment than bacon! *Phew* We can keep that sarnie and stop global warming!

But here's the thing about scientific studies, you generally need to read them to understand them, especially before you write gloating lines about vegetarian diets being worse for the environment. If you are about to write those lines, it's best to see what the study said about vegetarian diets.

This particular study mentions vegetarianism in only one section. In that section, the study says, quite explicitly: "The results of these studies demonstrate that adopting a vegetarian diet or even reducing meat consumption by 50% is more effective in reducing energy use, the blue water footprint, and GHG [greenhouse gas] emissions through the food supply system than adopting a healthier diet based on regional dietary guidelines."

The study itself actually compared current US diets with the recommended diet of the United State Department of Agriculture (USDA) – a diet that includes meat (though decreased) and fish (increased) – not a vegetarian one.

Lettuce yum
Eating the recommended amount of calories, regardless of diet, reduces the environmental impact.Reuters

What the study did was compare recommended diets in the US with current diets in the US based on their environmental impact per calorie. That's the important part – per calorie.

Per calorie, fruits and vegetables have an incredible high environmental impact because, well, they don't have many calories. To take this and then presume that vegetarian diets are worse for the environment makes the false assumption that people who eat less meat are packing their plates full of more and more vegetables to get those calories. One hundred grams of pan-fried bacon, for example, contains 541 calories – to get 541 calories from lettuce you would have to eat 3.6kg of lettuce. KILOS. And no-one is doing that. Calories are made up with things like grains and pulses, which – according to this same study – have low impacts.

Not completely useless

But before we dismiss the whole report as useless, it actually had some really interesting and important points about our dietary habits. Firstly, it once again confirmed that meat, seafood and dairy were the top three food groups in terms of greenhouse gas emissions.

As Anthony Froggatt, a research fellow at Chatham House, said, "I think that meat production is in general more resource intensive than for other food groups. in addition to its water/energy use and emissions, there are significant implications for land use, with around 75% of the world's agricultural land and 23% of its arable land used to raise animals, through growing crops for animal feed and through the use of pastures as grazing land. It is important to note that the study confirms, that meat, poultry and egg food groups as a whole are relatively high sources of GHG compared to vegetable, grains, pulses and sugars. Therefore, reducing consumption of the former food groups, which is also recommended from a health perspective, in this, and other studies, can be an important opportunity of GHG emissions savings."

Secondly, it had another very pertinent finding – we eat too much. Eating the recommended amount of calories, regardless of diet, reduces the environmental impact. Its a very simple equation: if we eat less, we produce less and impact decreases. This study estimated that Americans on average eat 200 calories more than is recommended. Eating less would not just reduce our environmental footprint, it would help with other issues in the Western world – e.g. the obesity epidemic.

Unfortunately, that very important lesson from the study was overshadowed.

A well-made diet?

One other interesting point was whether the USDA dietary recommendations are intelligently designed. According to the study, similar research in European countries had found that the environmental impact of switching to state recommended diets was beneficial, which questions whether the USDA's recommendations are simply not taking environmental issues into account.

bacon sizzling
There are no vegetarians substituting those two rashers of bacon for the caloric equivalent 2 heads of lettuceReuters

The way we talk about food is incredibly important. Our diets can have massive effects on our lives, from simple things like our energy levels to larger issues of putting ourselves more at risk of fatal diseases – the need to talk about these things in an informed manner is potentially life-threatening, and doing so well can be life-changing.

This is not just an issue of reporters looking for an eye-catching headline, it's also about how scientists now present their papers. A study from the University of Utrecht found that scientists now feel like they need to use 'positive' language more and more to prove the importance of their work, which ends up meaning that non-sensational studies don't get the attention they deserve.

Whatever it is that gives people their prejudice against meat-free diets, it shouldn't overshadow good science. On the flip side, ethical decisions made about not eating meat don't make it right to spread bad science (no, cheese is not addictive).

So finally, no, there are no vegetarians substituting those two rashers of bacon for the caloric equivalent two heads of lettuce… what a breakfast.