ROME — Sustainable development will not materialize so long as hunger and malnutrition persist, according to a document prepared by the Food and Agriculture Organization of the United Nations in advance of the Rio+20 Summit to be held this month in Rio de Janeiro.

“We cannot call development sustainable while this situation persists, while nearly one out of every seven men, women and children are left behind, victims of undernourishment,” said José Graziano da Silva, F.A.O. director general. “The quest for food security can be the common thread that links the different challenges we face and helps build a sustainable future. At the Rio Summit we have the golden opportunity to explore the convergence between the agendas of food security and sustainability to ensure that happens.”

Mr. Graziano da Silva said despite major progress in economic development and food production, hundreds of millions of people lack the means to either produce or purchase food needed for good health and productivity.

This problem forms the backdrop for the report, “Towards the future we want: end hunger and make the transition to sustainable agricultural and food systems.” In it, the F.A.O. urges governments to establish and protect rights to resources, especially for the poor; incorporate incentives for sustainable consumption and production into food systems; promote fair and well-functioning agricultural and food markets; reduce risks and increase the resilience of the most vulnerable; invest public resources in essential public goods, especially innovation and infrastructure.

Hunger reduction is inextricably linked to protecting the environment, the paper said. Noting that 30% of the world’s energy consumption is tied to agriculture and food systems, the F.A.O. said the crop and livestock sectors account for 70% of water use.

Rural areas are home to three quarters of the world’s poor, most of whom depend on agriculture for their livelihoods.

“Forty per cent of the world’s degraded lands are in areas with high poverty rates,” the F.A.O. said. “Hunger puts in motion a vicious cycle of reduced productivity, deepening poverty, slow economic development and resource degradation.”

The report said impediments to success for the 500 million small farms operating in developing countries need to be addressed, including the lack of food and nutrition for growers.

“They need clear tenure rights to promote equitable access to and sustainable management of resources like land and water,” the F.A.O. said.

Offering a “big picture” objective, the paper said more must be achieved with less when it comes to food consumption and production. Nutritious diets must be produced and made available with a smaller environmental footprint, and food losses/waste must come down from the current 1.3 billion tonnes per year, the F.A.O. said.

The importance of addressing these issues is heightened by the looming growth in the global population to 9 billion by 2050 and expected heightened food demand associated with rising incomes.

“Pressure on the world’s agricultural and food systems and the resources they use will grow,” the paper said. “Worse, unless purposeful action is taken, the increase in food production of 60% needed to meet effective demand will still leave behind over 300 million people who are expected to suffer from chronic hunger in 2050 because they will remain without the means to access food.”

Feeding all the of the world’s population is possible if bold policy decisions are taken on enhancing poor people’s access to food, reducing levels of food waste and addressing how agriculture is used for non-food purposes, the F.A.O. said.

“All depends on the choices made today in managing agricultural and food systems,” the paper said.

A good starting point for creating a sustainable food and agriculture system will be improved governance, the paper said.

“Part of the debate around good governance will also need to decide who pays for these costs,” the F.A.O. said.

The paper describes “fair and effective governance systems” as ones that are transparent, participatory, results-focused and accountable — at the global, regional, national and sub-national levels.

The Rio+20 event, formally named The United Nations Conference on Sustainable Development, will bring together world leaders, together with participants from governments, the private sector, non-governmental organizations and other groups to explore approaches to reducing poverty, advancing “social equity” and ensuring environmental protection.