At least seven children were at risk of being morbidly obese in Kirklees and Calderdale last year.
According to figures from the National Child Measurement Programme for 2015-16, four children in Kirklees and three in Calderdale had weight problems which could seriously affect their health.
The youngsters had a body mass index (BMI) of 35 or more, potentially making them morbidly obese if they are also suffering health conditions related to their weight.
One child in Kirklees weighed 14.6 stone and had a BMI of 38.1.
Someone is considered to be morbidly obese if they have a BMI of 40 or more or 35 or more if they are also experiencing obesity-related health conditions, such as high blood pressure or diabetes.
Overall, eight children in England are listed as having a BMI of 40 or more in 2015/16, with a total of 560 with a BMI of 35 or more who could potentially be morbidly obese. All of these children were in Year 6.
The child with the highest BMI listed in the NCMP data had a BMI of 40.8 and weighed 15.8 stone.
Overall two children are listed as weighing 16 stone or more.
The proportion of Year 6 pupils in England who are obese is at its highest level since at least 2006-07 at 19.8%, up from 19.1% in 2014-15.
There was also a small increase in the proportion that were overweight.