This one of the most prominent questions- What causes obesity? Average Joe may reply- poor diet & lack of physical exercise. However, it has a lot to with behavioural, physiological & personality traits. It is a well known fact that obesity is associated with a person’s tendency to face negative emotions. It is also connected with poor executive function- lack of ability to plan, pay attention & inhibit impulsive behaviours while performing a work.
Our behavioral, personalities & all actions originate from the most complex organ of the body- the brain. Obesity may not arise solely from dietary eating & exercise habits but also structure & activities of the brain. Some of these brain activities which vary from person to person are hereditary – they pass from generation to generation & are underpinned by variation in our genes. If we look at the bigger picture- obesity may partly be a case that genes cause changes/differences in the brain, which in turn alters our behavior resulting in poor diet & exercise habits.
FTO obesity gene is one of the gene variants which is tested & evaluated. The “A” allele refers to increase risk of obesity & people carrying “AA” genome type are 70% more likely to be obese. In case of “A” allele carriers, these areas of the brain respond differently to high calorie foods. In cases of such genome types, brain reward circuits are more responsive to Ghrelin, a hormone that drives hunger. Such brain changes increase the desire for high calorie & junk food, thereby resulting in increase in weight. FTO genes impact body weight by changes in the brain.
A recent study published in the journal proceedings of National Academy of Sciences, genetic factors do contribute to high BMI score & obesity related brain changes. As per the study, identical twins share 100% DNA while non-identical twins & siblings share 50% of DNA on an average. If identical twins show ore similar traits as compared to siblings, the genes play an important role however, if both identical twins & non-identical/siblings show similar traits, environmental plays a more important role. It was found that higher BMI was linked to poorer Spatial reasoning & verbal memory. In terms of brain changes, obesity was associated with reduced thickness of a part of the brain called the right Prefrontal Cortex. This part of the brain largely impacts control of food intake.
This study/theory requires more detailed research. This is very relevant given the findings that 70% of obesity related genes are expressed in the brain. Some of the genes such as FTO & MC4R impact our eating behaviour.
