The former Beatles star and two of his daughters, fashion designer Stella and photographer Mary, are heading the Meat Free Monday initiative, which persuade Britons to drop animal products from their diet for one day per week.
Macca insists that if people eat less meat it will help to improve the environment. However, officials at the National Farmers Union (NFU) have criticised the idea, insisting the star has overestimated the environmental problems caused by manufacturers.
"Diet is a lifestyle matter, and individual choices must be respected, but this campaign has a rather gimmicky air to it," the Daily Express quoted a spokesperson for the NFU as saying. "It greatly overstates the contribution that British livestock make to climate change, compared to, for example, transport where emissions have been rising rapidly in recent years," the spokesperson added.