Tearfund says some people too weak to work the land are resorting to searching ants' nests for food and have to walk up to 40km to find water.
The organisation say an estimated 5.9 million chilldren in the affected Sahel region - which includes areas of Chad but also stretches west into Senegal - will suffer from acute malnutrition this year.
Mother-of-six in Hillé Bar village, Jumana, said: "We do extreme things to survive. I used to be a very strong woman, but now I have been reduced to thinking only of how I can feed my family."
It is thought conflict, a depletion of natural resources, poor governance, high population growth, market prices and climate change have made the situation in the area worse.
Chad is thought to be one of the world's poorest countries.
Tearfund's chief executive Nigel Harris said: "Tearfund's partner in Chad, PEDC, is doing some powerful work to combat hunger and help people strengthen their resilience to disasters.
"But this is a complex food crisis with multiple causes, so we need to tackle it on a broad front.
Pauline from Tearfund's local partner PEDC: "In the Bible, we see Jesus doing miracles to feed multitudes of people. I believe that if he were here, he would do the same thing to feed the people here."
Listen to Premier's Hannah Tooley speaking to Levourne Passiri from Tearfund: