In 2020, the global agricultural output could have supported 15 billion individuals, yet only around half of those calories made it to people’s tables. This figure is expected to have further declined as the efficiency of the global food system diminishes.

Rising meat production, particularly in beef, alongside biofuels like ethanol and biodiesel, primarily drives this inefficiency, according to Paul West from the University of Minnesota and his team. A shift towards healthier diets and a reduction in biofuel production may enhance food availability without the need for additional agricultural land.

While food production is typically gauged in mass, evaluating it from a calorie-centric perspective (the energy content of food) offers greater benefits for comparing different crops and determining necessary quantities for individuals.

The team relied on data from the Food and Agriculture Organization of the United Nations, focusing on the top 50 crops contributing to global calorie production. These crops account for a staggering 97.5% of all calories grown worldwide, including staples like corn and potatoes, oilseeds such as sunflower and rapeseed, and fruits and vegetables like cacao, bananas, and tomatoes.

The researchers then analyzed how efficiently animals convert feed into meat, milk, and eggs, calculating the resulting calorie losses in animal-based food production. To avoid short-term fluctuations, they averaged their findings for 2010 and 2020 over three years.

The data indicated that global total calorie production experienced a 24% surge between 2010 and 2020, yet the edible calorie supply only grew by 17%.

This discrepancy arises from an increase in calories fed to livestock, notably beef, which is less efficient in converting feed into meat compared to chickens. In fact, 45% of the calories produced in 2020 were lost in the animal food production process. Transitioning from beef to chicken could mitigate these calorie losses.

Additionally, 5% of the produced calories in 2020 were allocated for biodiesel and bioethanol production, with a notable 34% increase in the calorie usage of palm oil for biodiesel.

This study does not encompass food waste, which further contributes to calorie losses. It highlights that not all food waste is created equal, particularly noting the significant waste associated with animal products like beef.

“The challenge of feeding 8 billion people today illustrates that the difficulty in sustaining future populations lies not in biophysical limits but rather in distribution and human choices regarding resource allocation,” remarks Hannah Richie from Oxford, who was not part of the study. “Calories aren’t the sole concern; protein and micronutrients also hold significant importance. I hope the team broadens their research to include these aspects.”

New Scientist reached out to West for comments, but he declined to discuss his study prior to its publication in a peer-reviewed journal.