The leaked World Food Summit draft declaration falls short of a UN goal of eradicating hunger by 2025. Instead, leaders are expected to to sign a watered down declaration in Rome next week that calls for vague increases in aid for farmers in poor countries but sets no targets or deadlines for action.
Leaders are expected to reaffirm their commitment to the UN's Millennium Development Goal of halving the number of hungry people by 2015 - a target that is unlikely to be reached.
The UN's Food and Agriculture Organisation (FAO), which is organising the three day conference, had hoped to win a clear promise from rich countries to increase the amount they give each year in agricultural aid from $7.9 billion (£4.8 billion) to $44 billion.
But a final draft declaration instead made only a commitment to "substantially increase the share of official development assistance devoted to agriculture and food security based on country-led requests".
"The declaration is just a rehash of old platitudes," said Francisco Sarmento, food rights coordinator for ActionAid.
Campaigners condemned the fact that the summit will be attended by only one G8 leader - Italy's prime minister, Silvio Berlusconi, who is hosting the gathering.
Britain will be represented by two junior ministers, Mike Foster, from the Department for International Development and Jim Fitzpatrick, of the Department for Environment, Food and Rural Affairs.
The US, the world's biggest food aid donor, will send the acting head of the US Agency for International Development.
More than 60 world leaders are expected, including Pope Benedict XVI, Col Gaddafi of Libya, Zimbabwe's President Robert Mugabe and Hugo Chavez of Venezuela.
"It's a tragedy that the world leaders are not going to attend the summit," said Daniel Berman of Medecins Sans Frontières .
Aid groups said the summit was a missed opportunity to tackle malnutrition, which kills a child every six seconds, despite the fact that the world produces a surplus of food. Cereal crops this year are expected to be the second largest ever, after a record harvest in 2008.
According to FAO, the number of hungry people rose this year to 1.02 billion people, as a result of the global economic crisis, high food and fuel prices, drought and conflict.
"This scourge is not just a moral outrage and economic absurdity, but also represents a threat for our peace and security," said FAO's director, Jacques Diouf, who will embark on a 24 hour fast on Saturday to show solidarity with the world's hungry.