From FAO "The Right to Food"
The right to adequate food as a human right was first formally recognized by the United Nations in the Universal Declaration of Human Rights (UDHR) from 1948, as a part of the right to a decent standard of living. In the UDHR Article 25 it was stated that:
"Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing, housing and medical care and necessary social services, and the right to security in the event of unemployment, sickness, disability, widowhood, old age or other lack of livelihood in circumstances beyond his control."
It was further recognized in Article 11 of the International Covenant on Economic, Social and Cultural Rights, a binding instrument for those states having ratified it.
In 1999, the right to food was interpreted by the Committee on Economic, Social and Cultural Rights (CESCR) in the General Comment 12 establishing that:
"The right to adequate food is realized when every man, woman and child, alone or in community with others, has the physical and economic access at all times to adequate food or means for its procurement."
In addition, the United Nations Special Rapporteur on the Right to Food also defined the right to food:
"The right to have regular, permanent and unrestricted access, either directly or by means of financial purchases, to quantitatively and qualitatively adequate and sufficient food corresponding to the cultural traditions of the people to which the consumer belongs, and which ensure a physical and mental, individual and collective, fulfilling and dignified life free of fear."
List of countries and their signatory/ratification status of CESCR:
FAO, "The Right to Food," http://www.fao.org/righttofood/about-right-to-food/en/ More source embedded in text