The Department of Health and Social Care said the guidelines are are voluntary – but said the government may take further action if the 2024 targets are not met.A spokesman said the industry was being asked to “do the right thing” and cut the calorie content of their foods by a fifth. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. A Cabinet minister has urged health officials to leave the public alone, in a backlash against planned calorie limits on restaurant and supermarket meals.Liz Truss, chief secretary to the Treasury, expressed frustration after The Daily Telegraph revealed proposals to cap the maximum calories in thousands of common foods.It came as think tanks criticised the plans drawn up by Public Health England (PHE) with the Adam Smith Institute and Institute of Economic Affairs calling for the body to lose its funding.Under the plans, the food industry has been given until 2024 to cap calories to new limits, with a maximum of 554 calories for a ready meal, 550 calories for a sandwich and a limit of 951 calories for a main course in a restaurant.Ms Truss was among those expressing horror at the proposals, which come days after the country’s chief medical officer proposed a slew of taxes on sugary and salty foods.In a tweet on Boxing Day she urged PHE to “leave us alone” joking that she was “too busy eating to engage with this”.Sources said she was “exasperated” at the use of public money to lecture the public, and feared that the latest proposals to cap calories in common foods would result in extra regulation, driving up costs to shoppers. Last month, a survey commissioned by PHE found that that the public thought the greatest responsibility for tackling obesity lies with individuals, ahead of government or the food industry.Ninety per cent of people thought individuals and families should take a great deal of responsibility for tackling obesity, with 72 per cent seeing government should take a role, and 80 per cent seeing industry as responsible.Tam Fry from the National Obesity Forum, backed the idea of a cap on calories. But he said the specific proposals seemed unrealistic, suggesting the limit for a main meal should be closer to 800 calories. Diet versions of ready meals are likely to pass muster, under the proposed rules Tam Fry from the National Obesity Forum, backed the idea of a cap on calories. But he said the specific proposals seemed unrealistic, suggesting the limit for a main meal should be closer to 800 calories. The draft proposals from PHE set out recommended limits for thousands of dishes, including a limit of 134 calories for a vol-au-vent or onion bhaji and a cap of 145 calories for salad dressing.Final recommendations are due to be published this spring, following consultation with the food industry.Manufacturers and retailers have already been set targets to cut the sugar content of common foods by a fifth by 2020.Last week Dame Sally Davies, chief medical officer, said companies were failing to make sufficient progress, and should be hit with new taxes on sugar and salt if the targets are not met. The Treasury minister has already criticised Government plans for mandatory calorie labels on restaurant menus, saying the policy would be too burdensome for small independent cafes and restaurants. A consultation is now considering whether exemptions to this policy should be made.