By the time these children are between the ages 10-11, more than 1 in 25 of them are likely to fall in the obese category-that amounts to 22,000 out of 556,000 kids.
The figures have shown that 23.6 per cent of year six children London-wide are obese and 10.3 per cent in reception are obese.
"Severe obesity rates vary significantly by area and are highest in children living in the most-deprived towns and cities, and those from BME groups, suggesting a need for the development and evaluation of more targeted interventions".
More than 22,000 children leave primary school "severely obese" and at increased risk of multiple health problems, according to new figures.
According to the report, it is estimated that nearly a third of children between the ages of two and 15 are classified as overweight or obese, and that younger generations are becoming obese early and staying that way for longer.
In Surrey, 2.08% are classed as severely obese in Year 6 compared with 1.09% in reception.
Dr Modi Mwatsama, of the Obesity Health Alliance, said: "This is a superb report that reflects what obesity campaigners have always been saying - the United Kingdom is in the midst of an obesity epidemic and the Government must take strong measures to tackle childhood obesity if we're to prevent this spiralling beyond control".
The National Obesity Forum's Tam Fry said: "Successive governments have failed for decades to take the action required to stop our children becoming unhealthily fat".
"Obesity rates are highest for children from the most disadvantaged communities and this unacceptable health inequality has widened every year since records began".
"The UK is already the most obese nation in western Europe, with one in three 10 and 11-year-olds and one in five four and five-year-olds classed as overweight or obese, respectively".
"Despite budget reductions, councils are spending more on running effective prevention schemes to help children stay healthy, which is key to tackling the child obesity crisis and reducing future costs to hospital, health and social care services", said the report.
"Cuts to councils' public health grants by Government are having a significant impact on the many prevention and early intervention services carried out by councils to combat child obesity".
"This short-sighted approach risks causing NHS costs to snowball due to the ill health consequences of obesity in our younger generation".
The NCMP is a government-run programme of measurement of all primary school-aged children in England and Wales.