Boris Johnson at Southern England Farms in Cornwall for Food Strategy

The Prime Minister denied the proposals fail to tackle obesity and said the best way to lose weight was to “eat less” as he visited a farm in Cornwall on Monday.

Mr Johnson was at Southern England Farms in Hayle, which later on its Facebook page to say: "An absolute honour to host the Prime Minister this morning where he used Southern England Farms to launch the UK's new Food Strategy."

"Even more fun was introducing him to Thomas and Amelia, the next generation. Well done SEF Team, a very proud day, thank you all for all your effort in making this happen."

During the visit the Prime Minister toured the farm, both out in the fields and inside its food production units, getting up close with broccoli and learning to drive a tractor.

Mr Johnson insisted he was “very grateful” for the work done by Leon restaurant co-founder Henry Dimbleby, who was behind the major review into the country’s food system.

But Mr Dimbleby has said some of his recommendations went ignored and the plan, being launched today (Monday), fails to take enough measures to address the UK’s health problems.

A team photo out in the fields Picture: Southern England Farms/Facebook

“I’m very grateful to Henry for all the work he has done. This is about helping to support UK food and farming at a particularly important time,” Mr Johnson told LBC Radio during the visit.

He added that innovation and technology in agriculture could “bring costs down for consumers” and allow for more domestic food production.

The proposals have been attacked for leaving out a sugar and salt tax that could help curb unhealthy eating.

Food minister Victoria Prentis insisted earlier on Monday that such a levy would be a “blunt instrument” to tackle a “complex” problem.

The MP said “voluntary initiatives” could work, despite stark warnings including from Mr Dimbleby that Government intervention is needed to help reduce child obesity.

Weighing in on the obesity debate during his farm visit, the Prime Minister said: “What we don’t want to do right now is start whacking new taxes on them that will just push up the cost of food.”

Boris Johnson talks to farm manger Gordon Stokes Picture: Justin Tallis/PA

He added: “The best way to lose weight, believe me, is to eat less.”

But speaking to the Guardian, Mr Johnson’s food tsar said the plan was “not a strategy”, saying: “It doesn’t set out a clear vision as to why we have the problems we have now and it doesn’t set out what needs to be done.”

The National Farmers Union said ministers had “stripped to the bone” proposals from the Dimbleby review, while Labour said the document was “nothing more than a statement of vague intentions”.

Launching the strategy on Monday, the Government said it had accepted “the majority of recommendations” from the food tsar’s report, with policy initiatives to boost health and secure food supply.

The Prime Minister talks broccoli and brassicas Picture: Southern England Farms/Facebook

One clear priority for ministers is to reduce the distance between farm and fork, with a vision for 50% of public sector food spend to go on food produced locally or certified to higher standards.

The strategy also sets out plans to create a new professional body for the farming and growing industry to boost training and equip businesses with skills needed to work sustainably and profitably.

The review also urged the Government to “nudge” consumers into changing their meat-eating habits.

But Environment Secretary George Eustice confirmed on Monday that ministers did not want people to lessen their consumption, telling the BBC’s Today programme that technologies could be used to reduce methane emissions from livestock production instead.