Two types of obesity

Almost two billion people worldwide are overweight, and more than 600 million people are obese. Using an approach based solely on data collection, the research team of Dr. Andrew Pospisilik from the Van Andel Institute, USA, showed for the first time that there are at least two different metabolic subtypes of obesity, each with its own physiological and molecular features that affect health in different ways.

Currently, obesity is diagnosed using the body mass index (BMI), which is calculated by comparing weight in relation to height. But this method is not ideal, because BMI does not take into account the main biological differences and can distort information about a person's health status.

Using laboratory data on mouse models and in-depth analysis of data from the pioneering TwinsUK research resource developed in the UK, Pospisilik and his colleagues found four metabolic subtypes that affect body type: two prone to thinness and two prone to obesity.

The first of the two obesity-prone subtypes is characterized by a greater fat mass, while the other is associated with an excess of both fat and muscle mass. The second type of obesity is also accompanied by more pronounced inflammation, which increases the risk of cancer and other diseases. Both subtypes were observed in several cohorts studied, including children. The team tested the results on mouse models and found that the inflammatory subtype of obesity appears to be the result of epigenetic changes caused by simple chance. They also found that genetically identical sibling mice either grew to a large size or remained small in size, without any middle variant. A similar pattern was observed in humans when analyzing data from more than 150 pairs of twins, each of which was almost identical genetically.

Thus, the researchers identified two different subtypes of obesity, one of which turned out to be epigenetically triggered and is characterized by higher muscle mass and more fat, high levels of inflammatory proteins, hyperinsulinemia and stable epigenetic markers.

Depending on the calculation method and the characteristics under consideration, only 30-50% of human features may be related to genetics or environmental influences. This means that almost half of who we are is controlled by something else. This phenomenon has been called unexplained phenotypic variability, and it represents both a problem and untapped potential for researchers.

Unexplained phenotypic variability is probably related to epigenetic processes that determine when and to what extent certain genes are active in DNA. Epigenetic mechanisms are the reason that people with the same genotype – twins – can grow up with different traits, such as eye color and hair color.

The results of the new study emphasize the importance of recognizing these epigenetically mediated differences between people for a more accurate understanding of the health status of individual patients and the provision of quality medical care.

Article C.-H.Yang et al. Independent phenotypic plasticity axes define distinct obesity sub-types is published in the journal Nature Metabolism.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the Van Andel Institute: Scientists redefine obesity with discovery of two distinct subtypes.