Dundee has the worst obesity rate for Primary One children in mainland Scotland, according to official figures.
There were 272 children aged 4-5 in the city clinically assessed in 2017-18 as obese or overweight, which is one in six of its P1 population.
Charities have turned their fire on supermarket price promotions as they warn of the cancer risk to the country’s youngest pupils.
Professor Linda Bauld, from Cancer Research UK, said: “When we’re seeing so many children as young as 4 overweight and obese, it’s clear the need for urgent action has never been greater.
“Supermarket multi-buy offers on junk food and sugary drinks are fuelling this alarming trend, encouraging us to stock up on unhealthy food.”
In Dundee, 17.8% have a BMI that makes them obese or overweight, according to NHS Scotland’s annual child obesity report. Only the Western Isles is higher in Scotland.
The percentage of children in the Tayside city at risk of having those weight problems is a local record of 26.9%, which is the highest in the country.
A Dundee City Council spokesman said: “We work closely with partners including NHS Tayside to help improve the health and wellbeing of all our pupils.
“We want to increase overall participation in physical activity and this includes initiatives like the daily 15 minutes of activity and outdoor learning.
“We also encourage our young people to take up healthy options.
“There is a focus on health and wellbeing across the curriculum to help our pupils learn health lessons for life.”
Alex Cole-Hamilton, for the Scottish Liberal Democrats, said the figures show the poorest youngsters are most in danger of being obese.
“It’s really worrying to learn that children’s backgrounds continue to have such a serious influence over their health. These statistics ought to ring alarm bells for ministers.”
Scottish Conservative Bill Bowman described it as a “health time bomb which is ticking ever more loudly on the SNP’s watch”.
The North East MSP said: “There should be no obese children in Tayside, at primary one or any stage of education.”
A Scottish Government spokesman said: “We’re aiming to half childhood obesity by 2030 through a range of measures designed to help people make healthier choices, including proposals to restrict in-store promotions and marketing of food that is high in fat, sugar or salt but with little or no nutritional benefit.”