Last week in Trafalgar Square, British historian and freegan Tristram Stuart served lunch to 5,000 people. The meal was made from 6 tons of food that would otherwise have been thrown away by farmers, supermarkets and wholesalers because of failed cosmetic inspection, overproduction or expired sell-by dates. All of the food was perfectly edible. Although not strictly a hunger relief event, the meal was a practice in mindful eating and food redistribution. In Stuart’s view, we could be doing even more to cut waste on a global scale. His newest book, Waste: Uncovering the Global Food Scandal, demands that we eat all the food we buy and become informed about larger inefficiencies in the food system.

Much of Stuart’s purpose in Waste is gauging the monetary value of discarded food and the volume wasted, as well as the damage caused to nutrients and the environment. But most available statistics are outdated and based on estimates and recent trends. This alone is a convincing illustration and indictment of government indifference to food waste. Still, approximations begin to explain what waste looks like. In the UK, discarded food would be enough to feed 30 million people – at a rate of 250 kcal more per day, easing malnutrition. In the US, retailers, food services and households toss 33% of all purchased grain-based food — sufficient food to feed 194 million people. If you consider the grain used to fatten animals whose meat we throw away in turn, another 1.5 billion people could have been aided.

In the developing world, waste is most apparent at the post-harvest level. “A lack of basic agricultural infrastructure and training” depletes food supply before products reach hungry mouths. India, the third-largest agricultural and cereal producer in the world, wastes around 35-40% of its fruit and vegetables because of poor storage facilities and refrigeration. Still, Stuart calculates the numbers necessary to create potential savings: “if all countries kept their food supplies at the recommended 130 per cent of requirements, and poor nations reduced their post-harvest losses, then 33 per cent of global food supplies could be saved. This level of ‘unnecessary surplus’ would be enough to relieve the hunger of the world’s malnourished twenty-three times over, or provide the entire nutritional requirements of an extra 3 billion people.”

How do we enact change? Stuart argues that education, conservation of our resources, “financial incentives,” supplier transparency, and “even legislation” would force all guilty parties to reform. On what Stuart calls the “islands of hope”—Japan, Taiwan and South Korea—consumers have learned to curtail waste. In Japan, a 2001 Food Waste Recycling Law required food companies to recycle 48% of their food waste—reformers have now upped that number to 66% by 2012.  Targeted businesses are moving toward innovative methods for livestock feed production. Although Japan “currently imports 90 per cent of its concentrated, high-protein, high-carbohydrate livestock feed,” 37% of food recycled is made into livestock feed.

Stuart discusses how certain processing plants are practicing an “organic-retail loop” whereby a food corporation supplies a processing plant with waste to produce swill. The corporation then buys back the pork, fed on the processed animal feed, to sell in its stores. In Taiwan and South Korea, dumping food in landfills is outlawed—some waste is processed for animal feed, some is composted. By prohibiting food from reaching landfills, lawmakers make a powerful planetary statement against methane gas emissions that occur when food decomposes underground.  Stuart also shows how we would erase carbon emissions caused by cultivating land to harvest animal feed, if we fed food waste directly to animals. 1 million liters of water per ton would also be saved.

How much would we have to give up in order to make positive planetary changes? Not that much—eat the food you buy, to begin with. In Stuart’s world of “Good-Eating”: