Health campaigners have warned an "obesity epidemic" is gripping Scotland as new figures showed almost a quarter of children are at risk of being overweight when they start school - a level which has remained "broadly similar" for a decade.
Official NHS statistics for 2015-16 showed 22.1% of P1 pupils had a BMI level which puts them at risk of being overweight or obese.
That includes almost one in ten (9.9%) youngsters whose weight is so high they are classed as being at risk of obesity.
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While 6.6% of P1 pupils in the least-deprived areas fall into this category, the proportion in the poorest areas is almost double that level at 12.7%.
The NHS warns obesity during childhood "is a health concern in itself", adding the problem "can also lead to physical and mental health problems in later life such as heart disease, diabetes, osteoarthritis, back pain, increased risk of certain cancers, low self-esteem and depression".
Just over three-quarters (76.8%) of P1 pupils in 2015-16 were classed as being a healthy weight, with 12.2% at risk of being overweight, 9.9% at risk of obesity and 1.1% in danger of being underweight.
The statistical report said: "The BMI distribution of children in primary one has remained broadly similar over the last decade."
Professor Linda Bauld, Cancer Research UK's cancer prevention expert, based at the University of Stirling, warned: "The fact that so many children as young as four are entering primary school carrying too much weight is a stark reflection of the obesity epidemic that's gripping Scotland."
She said the Scottish Government "can and must now do more, including tackling the barrage of supermarket multi-buy offers on sugar and fat-laden food and drinks".
Prof Bauld continued: "Obesity is also linked to 13 types of cancer including bowel, breast and pancreatic. If left unchecked, we run the risk of obesity becoming a crippling burden on society and the NHS."
Over the period 2006-07 to 2015-16, the proportion of P1 pupils at risk of being overweight and obese has been between 21% and 23% while between 1% and 2% of youngsters this age are at risk of being underweight.
The 2015-16 figures showed 22.3% of boys at risk of being overweight or obese, compared to 21.8% of girls.
Liberal Democrat health spokesman Alex Cole-Hamilton said: "Children must be given every opportunity to have a healthy lifestyle and be fit for the future.
"However, the rate of primary one children who are overweight or obese hasn't shifted in a decade.
"Scotland isn't winning the battle of the bulge and one of the most important ways to turn this around is to make progress in the early years.
"Ministers must step up their efforts to promote physical activity and healthy eating, giving the children the best start in life."
Scottish Green health spokeswoman Alison Johnstone said the number of youngsters at risk of being overweight or obese was "gravely concerning".
She said: "We already know that obese children are around five times more likely to become obese adults and the condition is linked to cancers including bowel, breast and pancreatic.
"The cost of obesity to the NHS in Scotland is already estimated at £600 million a year.
"There are immediate steps the Scottish Government can take to remedy this, like increasing and improving physical education at school, but fundamentally we have to improve living standards for many of the poorest in our society, a task that will require more than just the Health Secretary to be involved in."
Scottish public health minister Aileen Campbell said: "We are committed to addressing Scotland's excess weight and have announced our intention to consult on the development of our new Diet and Obesity Strategy in 2017, building on our wide range of activity to make it easier for people - including children and their families - to be more active, eat less and eat better.
"We are investing in a range of areas to support healthier lives for children and families, including investing £149 million in free school meals for all primary one to three children, a total of £11.6 million in supporting schools meet our PE manifesto commitments between 2012-2016 and £50 million for Active Schools.
"We recognise we need a shift in emphasis from dealing with the consequences to tackling the underlying causes, such as ending poverty, fair wages, supporting families and improving our physical and social environments.
"That's why we are driving investment in affordable housing and continuing commitments including free prescriptions, concessionary travel and free personal care."