Is Obesity Hard-Wired in The Brain?

The escalating obesity rate has become a tricky issue for many countries. This is because obesity can eventually lead to development of many diseases, including heart disease, diabetes, hypertension (high blood pressure) and stroke. The expecting cost of dealing with these diseases can be huge, which will become a burden not only on the people but also on the government.

Many health experts have frequently blamed the modern lifestyle of overeating, inappropriate diet and lack of exercise as the cause of overweight and obesity. However, a study by the researchers from the University of Southern California, Los Angeles found that obesity might be hard-wired into the brain from birth so that some people are more prone to overweight than others.

The findings of an animal study, appearing on in the February 2008 issue of Cell Metabolism, showed that obese rats had faulty brain wiring that impaired their response to the hunger-suppressing hormone leptin.

It seemed that appetite and obesity were built into the brain for obesity-prone rats, according to the researchers. The neurodevelopment differences in these animals could be seen as early as the first week. Such results showed that obesity could be wired into the brain from early life.

Leptin, produced by fat tissue, plays a central role in fat metabolism by acting as a signal to the brain about the body's energy status. Though scientists are still not clear about its role in weight regulation, they are aware that the brain calibrates the requirement for food intake partly based on leptin levels.

Learnt from previous research that the brains of obesity-prone rats were insensitive to these leptin signals, the researchers looked for brain abnormalities that could explain this.

In the study, they found defects in the brain circuits that relay leptin signals throughout the hypothalamus. Hypothalamus is the brain’s central switchboard for regulating conditions in the body.

The findings showed that exercising and eating right might improve the rat’s condition, but the propensity to gain weight could not be reversed.

The researchers also pointed out that if the findings are replicated in humans, then those individuals who are genetically predisposed to obesity as a result of their brains’ configuration should carefully pay attention to diet and energy balance.

Meanwhile, they also cautioned that the general belief that weight regulation is all a matter of nutrition or lifestyle choices might not be helpful for people whose biology predisposes them to obesity.