Not the End of the World: How We Can Be the First Generation to Build a Sustainable Planet

by Hannah Ritchie

This simple relationship is useful: smaller animals are more calorie-efficient. Fish and chickens tend to be the most efficient, then pigs, then sheep, then cows.vi Unfortunately this means the opposite for animal welfare: you’d need to kill more of them to get the same amount of meat. How you balance that moral quandry is up to you. Measuring ‘calorie efficiency’ tells us what percentage of the calories we feed an animal is converted into ‘eatable’ products for humans. These figures are quite shocking. For beef, it’s just 3%.16, 17, vii This means that for every 100 calories we feed a cow, we get just 3 calories of meat back in return; 97 calories are effectively wasted. For lamb, it’s around 4%. Better than cows, but still crushingly bad. Pork is almost 10%. For chicken, it’s 13%. Even for the most efficient of animals, the vast majority – more than 80% – of calories are wasted. That fact is quite hard to stomach. Can you imagine buying a loaf of bread, cutting a slice, and throwing the rest – more than 90% of it – in the bin? When it comes to calories, that’s pretty much what we’re doing with meat.