Dartford and Gravesham have the largest percentage of older primary school children in Kent who are overweight or obese.

The latest health figures show a massive 38.9% of 10 to 11-year-olds resident in Gravesham fall into this category, with Dartford only slightly slimmer at 35.6%.

The figures, published by government-sponsored agency Public Health England (PHE), reveal Gravesham weighs in as having the largest percentage out of 13 local authorities in Kent, with Dartford in second place.

Based on calculating body mass index (BMI) by using weight and height, they also make bleak reading as far as younger children are concerned.

Dartford has 25.6% of Reception Year pupils – four to five-year-olds – classified as obese and overweight, again the highest in Kent It is also above the Kent average of 22.5% and national average of 21.9%

The figures improve for the same age category in Gravesham, which is ranked seventh with 22.5%. However, in respect of 10 to 11-year-olds both boroughs are above the county average of 32.8% and national average of 33.2%.

Gravesham also has the highest percentage of obese Year 6 children at 22% while Dartford narrowly beats Thanet in respect of obese Reception pupils with 11.1%.

Swanley, which is covered by Sevenoaks council, has the lowest percentage of obese and overweight Year 6 youngsters with 27.5%, and the joint second lowest of 20.6% of Reception children.

But while the figures have been branded “concerning” by Dartford MP Gareth Johnson (Con), he issued his own warning over the statistics.

“While it’s essential to promote healthy eating and exercise among children, we need to approach this issue with caution,” said the father-of-two. “I have always felt uneasy about the current definitions of what constitutes obesity.

“Very often both adults and children are told if they are above a certain weight then they are obese but in reality they look perfectly normal.

“We must not fall in to the trap of pressurising children to look like a stereotypical, skinny celebrity.”

More than 30,000 children in Kent and one million in England were measured as part of the National Child Measurement Programme to categorise youngsters as underweight, healthy, overweight or obese.

However, when calculating BMI in children, age and sex appropriate growth references are also used to correctly determine weight status.

On these centile charts, the 50th centile is seen as the average. Overweight is any weight on or above the 85th, with obese starting at the 95th.

The findings have been published as the pressure for the government to impose a sugar tax mount, with some health experts saying it should be as high as 50%.

But Mr Johnson said he was not convinced such a levy was the solution and that obesity should be tackled in other ways.

The number of people diagnosed with diabetes in Dartford, Gravesham and Swanley, has reached 12,831, an increase of 6.33% in the past three years, according to research.

The figures, released by Diabetes UK extracted from GP patient data, show the growth is higher than the increase in prevalence of the disease nationally of 5.93%.

In the UK, the number living with diabetes has tipped the four million mark for the first time. The charity also believes there are a further 549,000 people who have type 2 diabetes but are yet to be diagnosed.

Health officials have warned that many youngsters are consuming their own body weight in sugar each year, not only leading to weight problems but also tooth decay and type 2 diabetes.

On average, children aged four to 10 are consuming 22kg of added sugar a year – approximately 5,500 sugar cubes and more than the weight of an average five-year-old.

Public Health England has now launched a free phone app aimed at parents and which helps counts the amount of sugar in food or drink.

The calls for a sugar tax are not new and last year Dr Manpinder Singh Sahotacorr, from the Pelham Medical Practice in Gravesend, went so far as to say all sugary drinks should be banned.

Branding them lethal, he added: “I see too many kids and adults drinking these drinks when they are already very overweight.

“These drinks are one of the main reasons Gravesend and Dartford have high levels of obesity and high rates of diabetes.”

Last year, the figures revealed Gravesham had the highest percentage of obese and overweight four to five-year-olds countywide with 24.8%, while Dartford was placed sixth with 21.9%.

The Kent average for 2013/14 was 20.8% and nationally 22.5%.

Year 6 children living in Dartford were ranked the highest in the county with 36.8% considered obese and overweight, while Gravesham was second highest at 36%.

The Kent and national averages were 32.7% and 33.5% respectively.