The way that we currently measure food security severely underestimates the enormous scale of global hunger.

A new study suggests that if we truly want to put an end to malnutrition by 2030, as per the aim of United Nations' Sustainable Development Goals, then we need to consider a more holistic approach to food systems.

"There are two main issues with how we currently talk about food systems," says lead author Hannah Ritchie, a researcher in malnutrition and sustainable food systems at the University of Edinburgh.

"The first is that we focus our measure of food security in terms of calories (energy), when micronutrient malnutrition ('hidden hunger') affects more than ~2 billion people across the world."

"The second issue," she continues, "is that aspects of our food system are reported in tonnes or kilograms, and it's very hard to put these numbers in the context of how many people this could feed."

The new study is the first of its kind to quantitatively map how calories, protein, fat, essential amino acids and micronutrients make their way through the supply chain and onto our plates.

Gathering data on food balance, nutrient composition and food waste from the UN Food and Agriculture Organization (FAO), the authors of the paper converted all measurements to average per person per day (pppd) for the sake of comparison.

The findings clearly show that we are collectively producing more than enough calories, protein and micronutrients to sufficiently feed the world's burgeoning population. In fact, the results reveal that some nutrients were produced up to five times more than the average requirement.

But despite the abundance of global food production, problems in the supply chain, like food waste, distribution and nutrient losses, ensure that many people in the world remain hungry.

"With large inequalities in food availability, we know that many people will be deficient in several essential nutrients," explains Ritchie.

Today, approximately one billion people suffer from protein deficiency, two billion suffer from hidden hunger and close to 800 million suffer from caloric hunger. All the while, over two billion people are estimated to overconsume.

"This challenge exists across countries of all income levels, with a growing number of developing nations experiencing a "triple burden" - an increase in the prevalence of obesity in parts of the population alongside the wide prevalence of undernourishment and micronutrient deficiencies," the authors write.

Tackling this issue will not be easy, especially in the face of climate change and a rapidly growing population.

"With population growth, intensifying climate change impacts and rapidly changing diets, the need for evidence-based, holistic assessments of our food system has never been more urgent," says co-author and climate scientist David Reay, also from the University of Edinburgh.

The challenge of malnourishment is made even more difficult when problems in the supply chain differ for each specific nutrient.

For instance, the study reveals that we lose most micronutrients, like Vitamin A and C, in post-harvest waste of fruit and veggies, while energy and protein is lost the most when crops end up being used as animal feed and biofuel.

"This is important information to understand," says Ritchie.

"Knowing that the highest-impact interventions for maintaining micronutrients may not be the same as for calories, which may not be the same as for protein, will help to focus our efforts for food security and nutrition."

The paper does not put forward any solutions. It is simply meant to inform and point out areas where sufficiency can be improved and trade-offs can be made.

Dairy farming, for instance, is identified as a particularly difficult conundrum because it simultaneously helps and hinders global malnourishment.

"When you consider that more than ~80 percent of farmland is used for grazing or animal feed production, livestock are clearly an inefficient way of producing food," explains Ritchie.

"But, while livestock are an inefficient converter of feed, they remain the only natural dietary source of vitamin B12 and an important source of high-quality protein and lysine (an amino acid) for many people," she continues.

The authors acknowledge that their data does not zoom in on regional, national or local dynamics. Nevertheless, they maintain that it is replicable and useful on a broader scale.

"This study is just the start," concludes Reay.

"In the future, this replicable framework can be used to map food pathways for specific regions and countries. Our hope is that governments and development agencies can use it to assess food security risks and develop locally specific solutions."

This study has been published in Frontiers in Sustainable Food Systems.