The claim was posted on billboards around the country last September as part of a PETA campaign against eating meat. It prompted a furious response from the NFU, which asked the ASA to censure the animal rights group for trying to shock consumers.
But the ASA ruled the campaign was acceptable on the grounds that people expected extreme statements from a lobbyist and would not take it as seriously as the NFU suggested.
The NFU branded the ruling perverse and said it planned to lodge a request for an independent review. "The implication of this ruling is that any extremist organisation can say what it likes because its material will not be taken seriously.
"There is no ground for arguing that eating meat contributes to childhood obesity. For PETA to claim otherwise is wrong and damaging to health."