John Hoddinott is a Senior Research Fellow and Deputy Director of the Poverty Health and Nutrition Division at IFPRI.

In a few days’ time, high level representatives from governments, business, scientists, and civil society will meet in London to make ambitious commitments needed to tackle undernutrition. Why now? After all, photographs of hungry children seem to have been with us forever, and while these evoke sadness, they have never been enough to generate serious and sustained attention to this topic.

But this time, things really could be different. A growing body of evidence—amassed by nutritionists, neuroscientists and economists—is showing that undernutrition in the first few years of life has consequences that last a lifetime.

Undernutrition—the inadequate intake of nutrients from food often combined with repeated infections—has devastating effects on health, productivity, and mental function. More than 175 million pre-school aged children worldwide suffer from stunting, a direct consequence of chronic undernutrition. They will never fully catch up to their well-nourished peers. These children are growing up with spatial navigation, memory, and other neurological impairments and will grow up to be less productive workers, making a lower income. Those with a deficiency in specific nutrients, such as vitamin A, iodine, and iron can suffer from mental retardation, vulnerability to disease, and even death. But all of this is preventable. Research over the last ten years has shown that a bundle of interventions, including those addressing micronutrient deficiencies, dissemination of information on good nutrition practices to mothers, deworming, and, as needed, the provision of complementary foods and the management of acute malnutrition, can prevent undernutrition.

This costs money: $3 billion per year would allow 100 million children to live their lives free of malnutrition. Three billion dollars might still seem like a lot of money, but it’s a drop in the bucket—less than 5 percent of the $125 billion the world spends annually on development aid. But development spending is hard to grasp sometimes so here is another way of thinking about it. Every year, the average American spends about $350 each on fast food. But if everyone gave up a mere 3 percent of this—$10 or about three Big Macs a year—there would be more than enough money to meet this cost.

But cost is only part of the issue. Economists like me look at both the costs and benefits of actions. In a paper prepared for the 2012 Copenhagen Consensus—work that built on earlier efforts by economists such as Jere Behrman, Susan Horton, and my IFPRI colleague Harold Alderman—my colleagues Mark Rosegrant, Maximo Torero, and I found that the benefit-cost ratios of investing in proven nutrition interventions are large. When we presented this to a panel that included four Nobel economics laureates, the panel concluded that in economic terms, fighting undernutrition was the single most important investment the world could make—a recommendation that was included in the United Nation’s post-2015 development agenda. Of course, as we learn more about these interventions, these numbers will change – but what will remain true is that investments in reducing undernutrition can leverage great impacts.

Eliminating undernutrition has always been an intrinsically valuable goal. But we now know that its good economics. Let’s hope that all those meeting in London see it the same way.