Sugar limits for everyday foods such as biscuits, chocolate bars and cereals have been published by public health officials in a bid to make UK children more healthy.
Public Health England is challenging businesses to cut sugar by 20% by 2020, and by 5% this year.
It says the food industry should try lowering sugar levels, reducing product size or pushing healthier products.
But experts question how the targets can be enforced.
Children are consuming three times more sugar every day than they should, which can lead to weight gain and obesity.
Currently, one in five children are overweight or obese when they start primary school and by the time they start secondary school that rises to one in three.
This increases their risk of type 2 diabetes, heart disease and some cancers in adulthood.
Tonnes of sugar
Dr Alison Tedstone, chief nutritionist at Public Health England (PHE), said children from deprived backgrounds were more likely to be affected by obesity.
"Tackling the amount of sugar we eat is not just a healthy thing to do, but an issue of inequality for many families.
"If businesses achieve these guidelines, 200,000 tonnes of sugar could be removed from the UK market per year by 2020."
The guidelines apply to retailers and manufacturers as well as small cafes, coffee shops and fast food restaurants, which are thought to be responsible for an increasing level of calorie intake.
Food in nine different categories will have recommended sugar limits, including cakes, biscuits, chocolate and sweets, ice cream, puddings, yoghurts, breakfast goods and sweet spreads.
The sugar guidelines form part of the government's plan to curb childhood obesity, set out in August 2016.
Officials in Scotland, Wales and Northern Ireland have also been involved in producing the guidelines.
A sugar tax on the UK soft drinks industry has already been announced and will come into force next April.
PHE's sugar reduction programme is voluntary and it has no way of forcing the food industry to comply, but it said many companies had already taken steps to achieve the sugar targets.
It called the figures "challenging but achievable, particularly in higher sugar products".
Nestle, which makes Kitkat and Aero, recently said it had a found a way of reducing the sugar content of its chocolate bars by 10% without changing the taste.
Businesses are being encouraged to meet the sugar reduction guidelines using three approaches:
- cutting sugar levels by 20% across their products
- reducing the number of calories in a single serving or reducing the portion size
- pushing consumers towards "no added" or lower sugar products
This means that some popular chocolate bars and tubes of sweets could shrink in size to meet the targets.
PHE said the guidelines were based on extensive talks with the food industry and public health bodies.
It said the success of its sugar reduction programme would be judged on measuring the net amount of sugar removed from the nine food categories, starting in March 2018.
'Change in attitudes'
Graham MacGregor, professor of cardiovascular medicine at Queen Mary University of London and chairman of Action on Sugar welcomed the sugar reduction targets and urged companies to meet them.
"We've seen over recent weeks that some companies within the food and drink industry have made great progress whilst others are seriously lagging behind and others claiming wrongly that they can't do it.
"Doing nothing is no longer an option - we need transparency from them about how they are meeting the targets with clear nutritional information made available for restaurants, catering companies and other out-of-home eateries."
Sue Kellie, deputy chief executive of the British Dietetic Association, said people's behaviour needed to change as well.
"The government needs to further restrict the advertising of high fat, sugar and salt foods before the 9pm watershed and ban promotions on those same products.
"If we are to successfully tackle obesity and reduce its long term costs to the NHS and wider economy, we need to change attitudes and habits over the long term - there's no quick fix," she said.
Dr Amelia Lake, public health nutritionist from Durham University, said PHE was doing the right thing.
"This is an excellent approach using strong research evidence and we are being world leaders on the international stage in our sugar reduction programme.
"Not only are these foods commonly consumed by children - but also by the whole family."