Taxing sugar and salt in products is about reducing the “enormous harm” they do, not pushing up costs for hardworking people, the author of the proposal has said.

Henry Dimbleby’s National Food Strategy calls for a sugar and salt reformulation tax as a key part of efforts to transform the nation’s diet to include less sugar, salt and meat to protect health and the environment.

It warns that what we eat, and how it is produced, is doing “terrible damage”, with poor diets contributing to 64,000 deaths a year in England and costing the economy an annual £74 billion.

Current food systems are also driving wildlife loss and climate change, which in turn puts food security at risk, the National Food Strategy report said.

But after Boris Johnson said he was not attracted to the idea of extra taxes for hardworking people, Mr Dimbleby said the plans were designed to force manufacturers to reduce the amount of sugar and salt in products.

High levels of sugar and salt are harming people and putting an intolerable strain on the NHS, he said.

His comments come after the Prime Minister was quizzed on the move in a question-and-answer session following a speech in Coventry.

Mr Johnson said: “I will study the report. I think it is an independent report. I think there are doubtless some good ideas in it.

“I am not, I must say, attracted to the idea of extra taxes on hardworking people.”

Mr Dimbleby, food entrepreneur and co-founder of Leon Restaurants, said: “The Prime Minister said that he’s not attracted to the idea of extra taxes for hardworking people. I couldn’t agree more.

“But the sugar and salt reformulation tax is not about pushing up costs for hardworking people.

“It is designed to force manufacturers to reduce the amount of sugar and salt in their products, which are causing enormous harm to the people of this country and putting intolerable strain on the NHS.”

He added: “It is time to act and solve this crisis and I am delighted that the Prime Minister has said he will carefully study the findings of the National Food Strategy report.”

The report says some money raised by the tax should be spent on addressing the inequalities around food, by expanding free school meals, funding holiday activity and food clubs, and providing healthy food to low-income families

It also urges the Government to run trials giving GPs the option to prescribe fruit and vegetables for patients suffering from poor diets or food insecurity while food education should be central to the national curriculum, to reverse declines in cooking skills and knowledge.

While the report says meat consumption should be cut by 30% in a decade to cut emissions and free up land for storing carbon and preserving nature, it rules out a meat tax as politically impossible and unpopular.

Instead, the review urges the Government to “nudge” consumers into changing their meat-eating habits, for example by investing in alternative proteins.

It also calls on ministers to make sure the budget for payments for farmers to deliver environmental benefits, such as restoring nature, preventing floods and improving soils, is guaranteed until at least 2029.

And the payments need to be generous enough for land managers to make the switch from conventional farming to more sustainable options.

Food standards must be protected in any new trade deals to safeguard British farmers from unfair competition or even being bankrupted, and to prevent environmental damage from food production exported abroad, the strategy says.

The report also warns of the huge toll of disease caused by poor diets while the food we eat accounts for around a quarter of greenhouse gases and is the leading driver of habitat and wildlife loss.

In the UK, agriculture alone accounts for 10% of emissions, while contributing less than 1% of economic output, and livestock accounts for 85% of the farmland that feeds the UK both here and abroad, some of which domestically must be freed up for climate and nature initiatives such as creating woodlands.

To meet existing Government targets on health, climate and nature, by 2032 fruit and vegetable consumption will need to increase by 30% and fibre by 50%.

At the same time, consumption of food high in saturated fat, salt and sugar will have to go down by 25%, and meat consumption should reduce by 30%.

The National Food Strategy estimates its recommendations will cost around £1.4 billion a year and bring in £2.9 billion to £3.4 billion a year in direct revenue to the Treasury, with a long-term economic benefit of up to £126 billion.

The report has been backed by campaigners, including TV chef Jamie Oliver who said: “If both Government and businesses are willing to take bold action and prioritise the public’s health, then we have an incredible opportunity to create a much fairer and more sustainable food system for all families.”

Shadow environment secretary Luke Pollard said the report is a massive wake-up call to fix Britain’s broken food system, but accused the Government of being incapable of ending the food bank scandal and obesity crisis, and of making trade deals that betray British farmers.

The Environment Secretary George Eustice has said the Government will study the report’s findings and respond with a white paper setting out priorities for the food system within six months.