Dear Dragan, although this is not my area of expertise, recently I came across few studies that you may find useful.

DOI: 10.3109/17477166.2010.530664

DOI: 10.1519/JSC.0000000000000722

DOI: 10.2478/v10038-012-0012-7

DOI: 10.1007/s005860000230

With regards,

Aleksandar Gadžić

This will be useful for me. Thank you Aleksandar!

Best regards 

Hello, those articles may be helpful, even if it's not specific on children...

DePalma MJ1, Ketchum JM, Saullo TR.Multivariable analyses of the relationships between age, gender, and body mass index and the source of chronic low back pain.Pain Med. 2012 Apr;13(4):498-506.

DIO: 10.1111/pme.12039 

DIO: 10.1111/j.1469-7580.2011.01444.x

Best regards

Not aware of true epidemiologic research, there is a anatomic- physiologic relationship. 

Children that live a sedentary life and do sit only in flexed positions develop thoracolumbar kyphosis , that can become fixed and introduce all sort of shearloads in the lower spines. 

But in a flexed postion or with a fixed kyphosis, the diafragm and the loose hanging abdominal muslcles will not create a physiologic intra abdominalpressure ( sensoring in peritoneum and by plexus solaris. The hindered function of diafragm and rectus are underestimated factors in the obesity problem

So the sensation of "being full"will never reach their brains. 

In my 30 year of practice i did not see obese children   without these postural problems as a consequence of their sedentary lifestyle. It must be easy to do research inthis direction by assesing posture and neuromuscular tightness comparing obese and non obese children. 

pvl 

Dear Piet van Loon,

Thank you for answer. Aim of my research is to investigate relationship between BMI and postural disorder measuring with 3D photometric method. I am aware of fact that is in some way correlate with physiological and sociological aspect of children's life. In discussion I will try to explain result with anatomic/psyho/socio background because it is interdisciplinary problem. A must say that in my research i use good method, large number of participates and assessing posture with new methods. Once again, thank you for opinion.

Obesity children have increase lumbar curve and thoracic too, deformation in sagitall plane, scoliosis is becoming more in tin children, and low bone mass. Both spine deformity are increase with low physical activity.

https://www.youtube.com/watch?v=eMeYns9e7qg