14 DAY TRIAL // It looks like obesity is the great pandemy of this century since over a billion adults in the world are overweight and 300 million of them – clinically obese.
Today, in fighting obesity, most people only consider body mass, and completely ignore the amount of adipose tissue within the body, so biologist Aline Jelenkovic decided to make this the main subject of her PhD thesis.
She conducted a research on nuclear families in Greater Bilbao, including kids aged 2 to 19 years, to see to what extent corporal morphology is influenced by genetics and how much influence does the environment have.
The thesis gathered data concluding that the characteristics defining the height, the shape and the adipose tissue of the human body are hereditary at a rate going from moderate to high (0.28-0.69), and also that the environment plays an important role too.
In other words, the way humans are built is in part established by genetics and in part by environmental factors.
In phenotypes related to obesity, both factors have a large influence, but genetics does not affect all of them equally – for the characteristics that determine adipose tissue, the environmental factor is more important.
The paper goes on and explains that the overall increase in body mass noticed among the studied sample, can be justified by the increase of the adipose tissue, so the conclusion makes sense: controlling the amount of adipose tissue instead of the entire body mass, is the key in fighting obesity.
There is another factor supporting this conclusion, and that is the link between the adipose tissue and blood pressure.
It seems that blood pressure is influenced by the environmental factor more than it is by genetics (0.14-0.31).
And even if there are no common genetic and environmental factors that prove a proportional relation between blood pressure and obesity, the amount of body fat has genetic effects on blood pressure phenotypes.
Besides genetics and environment, there are two other factors that could be related to obesity, and those are biodemographics and socioeconomic status.
In her thesis, Jelenkovic also talked about the relationship between the body's morphology and the family as being a significant factor, even if not especially influential.
She said that, for example, that siblings share more environmental factors that have an effect over their corporal morphology, than parents and children do.
As for the socioeconomic factor, it is interesting how people with a higher economic status are also taller and have less adipose tissue.
This type of research is important because obesity really is a serious health problem, affecting more and more children – today, there are over 155 million overweight children and adolescents, of which 40 million are clearly obese.
The thesis was defended at the University of the Basque Country (UPV/EHU).