There is growing concern in England that children’s waistlines are expanding because they are copying adults by consuming 200-300 calories too many per day. Those ready meals of pizzas, burgers, savory snacks and sandwiches are just too enticing. Price-cutting promotions of junk food in supermarkets and the advertising of unhealthy food to children through family TV shows are making the eating habits of the young a health hazard.

As a consequence, the health agency Public Health England is to cut excess calorie consumption from all sources in its anti-obesity strategy for children in the UK. It could see the size of products reduced or ingredients changed in food and drinks bought in supermarkets, takeaways and restaurants. The PHE will consider the evidence on children’s calorie consumption and try to use the calorie reduction program to remove excess calories from the foods children are known to consume the most.

The agency hopes to replicate the progress that has been made over the past year on reducing the level of sugar in many products. However, whereas the Soft Drinks Industry Levy, issued to cut down on sugar in food products, was passed into law, the new calorie targets would be voluntary, at least at the start. That means that parts of the British food industry might join the campaign to reduce calories while other companies may not.

It is a choice that has no logic. The drive to make foodstuffs less calorific may fail because companies do not have to take part. If the government will only propose voluntary reductions, that could lead to some manufacturers trying to take advantage by retaining more sugar in their food products. Under the voluntary “responsibility deal” between the David Cameron government and industry, some supermarkets cut the salt in own-brand products faster than others and found they were at a competitive disadvantage.

It would be much better if ministers imposed mandatory cuts to calorie levels in food rather than leaving it up to voluntary action by manufacturers. The only way to achieve the targets that the government has set out is to ensure a level playing field across the food industry.

Although the government proposes targets for food companies to reduce the level of sugar in their products, the fact that these are voluntary and not backed up by regulation, renders them pointless. If the English calorie drive is set to be one of the most important health initiatives of its time, the words it is using in its campaign – “should, might, we encourage” – are too suggestive and too vague, devoid of any mandatory points.

Reducing calorie consumption from sources other than sugar is critical to reversing the worrying obesity trend. The new emphasis on sources of calories from ingredients other than sugar has been prompted by the fact that one in three British students leaves primary school either obese or overweight.

When the UK introduced a sugar tax on soda makers last year as part of an effort to reduce childhood obesity, the measure appears to have worked. Rather than risk higher prices damaging sales, soda companies reduced the sugar content of many of their products. But sugar tax became law; it was not left up to the whims of companies.

With food more readily available than ever before, this is not the time to pass recommendations but to pass laws. Basically, British authorities are saying that if the calorie program doesn’t work, the government would consider making the targets legally binding. The question is why wait until the industry does not respond before preparing to legislate? Fast food chains, takeaways, manufacturers and supermarkets must not wait to start making their food healthier; they should start reducing calories today, by law.