A World Food Programme survey on nutrition and food security in Darfur has found that almost half of all families are not getting enough to eat.
The WFP is aiming to provide food and vitamins for children under five
The survey confirms aid agencies' fears that the western Sudanese region is facing a serious food shortage.
The conflict between rebel groups and militias backed by the Sudanese government has forced more than 1.5 million people to leave their homes.
At least 70,000 people are believed to have died.
The survey is the first comprehensive assessment of food availability since the crisis began some 20 months ago.
The agency found that:
Almost 22% of children in camps for internally displaced people are malnourished
Almost half of all families are not getting enough to eat
Ninety-four percent of the displaced in Darfur are completely reliant on food aid for every mouthful they consume.
Much still to do
But the WFP said more than just food was needed to solve the crisis.
"While much has been done for months now to feed as many people as possible in Darfur, the survey underlines how much remains to be done," Ramiro Lopes da Silva, WFP country director in Sudan, said in a statement.
"But food alone is not enough - the response also has to be significantly stronger on water, sanitation and health."
The WFP went to all regions of Darfur and assessed those who had stayed in their villages as well as those in the camps.
For people who remained at home, food is scarce too. Prices at the markets have risen by 60%.
There will be at best only half the expected harvest in November and many farmers have no seeds or tools for planting for the next season.
The survey suggests the number of people relying on food aid will increase in the coming months, possibly up to two million.
The WFP wants to introduce full daily rations for displaced people, and food and vitamin supplements for all children under five and pregnant or breastfeeding women.
Mr da Silva said that until recently the WFP had been unable to do this because so many people were hungry and there was barely enough to go round.
Succeeding in this enormous task could save thousands of lives.
But the BBC's Imogen Foulkes says it will be logistically very difficult, not least because the security situation in Darfur remains volatile and aid workers cannot always go where they are needed.