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Physical control and coordination in childhood and adult obesity: longitudinal birth cohort study

BMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a699 (Published 13 August 2008) Cite this as: BMJ 2008;337:a699

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Classification of obesity into few sub groups may help to find the processes associated with poorer neurological or cognitive functions with obesity and type2 diabetes in obese adults.

Authors have combined the data available from past records in a
structured manner to enhance the knowledge on correlations between the
childhood defects and problems appearing in obese adults [1].

It is quite common in medical research to apply corrections based on
statistical techniques to highlight the correlation between two factors by
eliminating various types of biases, which cannot be eliminated at the
sample selection stage. In fact this process is essential to find the
actual level of correlation in spite of natural restrictions placed due to
differences in age, ethnicity and many other factors.

How ever if the sample consists two or more different categories of
people this approach may dilute the expected result. As an example before
diabetic patients were classified as type 1 and type 2 , correlation
between insulin concentration and blood sugar level in a patient sample
having both type of patients should have painted a some what blurred
picture, although it would have been useful to a reasonable extent. Once
the two groups are separated better analysis and treatment became
possible. As time goes on process is further evolving and the picture
becomes clearer with some more subgroups getting introduced.

Similarly obesity seems to be a physical property that can arise due
to various conditions. As an example having smaller number of large cells
and large number of small cells can cause virtually same weight, volume
and BMI (body mass index) .As the number of beta cells does not increase
after some time (after birth) insulin secretion capacity of increased beta
cell mass represents the result that has caused due to cell size increase
(without cell number increase). It is anticipated that obesity associated
with smaller number of beta cells is likely to have several problems [2].

Therefore it may be of interest to analyze the same data by dividing
the sample in to different sub groups (as an example based on gestational
age or/and birth weight)[3]. In fact differential analysis on different
criteria is likely to show stronger correlation between the identified
factors in certain categories and no correlation in some other categories.
Actually a notable deduction that can be made from direct observation of
the data provided is that over 70% of the obese people seem to be quite
normal.

Classification of obesity according to average cell size seems to
have a deeper meaning.
When the particle transportation across the cell surface is limited by
some factor (this can happen due to various reasons) rate of particle
transportation is determined by the cell surface area. On the other hand
same particle type consumption (when it is transported in side) or
production (when the cell produces these particles) is determined by the
cell volume. If the cells were spheres, then their volume would have been
related to the cube of the radius while their surface area would have been
related to the square of the radius. Obviously under those circumstance
particle transportation across smaller cells becomes much faster.

Although the cells are not perfect spheres, same property is more or
less applicable for other similar topologies. Therefore obese persons with
larger cells are likely to have a relatively higher probability of
particle transport problems.

Although the current study does not identify the specific biological
processes linking poorer physical control and coordination with later
obesity, it has provided a direction to future research.

References

1]

Physical control and coordination in childhood and adult obesity:
longitudinal birth cohort study

Walter Osika, Scott M Montgomery

BMJ 2008;337:a699, doi: 10.1136/bmj.a699 (Published 12 August 2008)

2]
Arya K Kumarasena
Problems may not get fully corrected by just adjusting the hormone levels
to normal range
http://bmj.com/cgi/eletters/337/jul28_1/a801#199825, 1 Aug 2008

3]
Association between psychological symptoms in adults and growth in early
life: longitudinal follow up study Y B Cheung, , K S Khoo, J Karlberg, , D
Machin,
BMJ 2002;325:749 ( 5 October )

Competing interests:
None declared

Competing interests: No competing interests

16 August 2008
Arya K Kumarasena
Consultant/Director
85,Braybrooke Place,Colombo2,Sri Lanka