The goal is part of the Scottish government’s Healthy Weight and Diet plan that will be published this summer.
Currently, 29% of children in Scotland are at risk of being overweight including 14% at risk of being obese.
First minister Nicola Sturgeon said obesity is a serious public health issue that cannot be ignored.
“Evidence shows obese children are likely to stay obese into adulthood and become more likely to suffer health problems such as diabetes and cardiovascular diseases at a younger age,” she said.
“To ensure that the steps we take are proportionate and deliver beneficial outcomes, we will consult widely with consumers, suppliers and retailers following the release of the new plan.”
Two in three adults in Scotland (65%) are overweight and obesity rates are among the highest in the world.
The cost of obesity to the NHS in Scotland is estimated at between £360m (€411m) and £600m (€685m) annually.
Junk food adverts and promotions plus multi-buy deals
Areas of focus include tackling junk food promotions and marketing of unhealthy food, such as multi-buys, that encourage overconsumption.
The Scottish National Party leader announced the target after meeting celebrity chef and health campaigner Jamie Oliver.
Sturgeon was one of the signatories of a letter sent to Theresa May, prime minister, last month that set out thirteen measures to tackle UK childhood obesity and was coordinated by Oliver.
Heather Peace, head of public health nutrition at Food Standards Scotland, said obesity is one of the most serious problems currently faced in the country.
“Food Standards Scotland has recommended a package of measures to urgently address this serious issue, and it’s essential that industry, government and the people of Scotland all work together to turn the tide on obesity.”
Professor Linda Bauld, Cancer Research UK’s cancer prevention expert, said obesity is the biggest cause of cancer after smoking and is responsible for around 2,200 cases a year in Scotland.
“Price promotions play a significant part in what families choose to put into their shopping basket. In the battle to protect the health of future generations, it’s crucial laws are introduced to restrict the damaging supermarket junk food price promotions that are contributing to the nation’s obesity problem.”
SNP MPs will also monitor UK government action on policies reserved to Westminster – such as the sugary drinks tax, regulation of broadcast and digital junk food advertising seen by children and labelling.
Action to reach ambitious target
Obesity Action Scotland said ‘strong and comprehensive’ actions will be needed to reach the target.
“The forthcoming plan must contain mandatory controls to restrict the promotion and marketing of foods high in fat, sugar and salt and improvements to the out of home sector so that we can ensure that healthy choices are affordable and accessible to everyone.”
Chair of British Medical Association (BMA) Scotland Dr Peter Bennie said the target to halve the rate of child obesity is a strong ambition against which to measure progress.
“Restrictions on marketing of unhealthy food and drink, better labelling, changes to planning policy, and the provision of free fruit and vegetables to primary school children are all important actions that doctors are looking to the Scottish Government to include in their coming obesity strategy.”
Dr Donald Macgregor, from the Royal College of Paediatrics and Child Health, said the announcement comes at a 'critical time' but must 'go further' to get a grip on the obesity crisis.
“We know that advertising is a direct driver for obesity so tackling price promotions will be key if we are to get a grip on the obesity crisis,” he said.
“However we’d like the Scottish government to go one step further by recognising that unhealthy fast food sold at pocket money prices is equally as unhelpful. We’d like them to protect child health by preventing new fast food outlets such as chicken shops and chip shops opening within close proximity to schools and colleges.”