A study published in the October 17 issue of the journal Science has revealed that overweight persons’ brains did not get enough gratification from eating, therefore making them eat more in order to compensate.

Researchers looked at 43 female college students aged between 18 to 22 years old and at a group of 33 teenagers ages 14 to 18, who covered the whole range within the very skinny and obese limits.

While inside a brain scanner, the women drank small amounts of both chocolate milkshakes and a tasteless solution that mimicked saliva, which were given to to them through a syringe used to squirt the liquid into their mouths (since moving inside a Magnetic Resonance Imaging scanner hinders accurate measurement of the brain's activity).

Results showed that swallowing the milkshake triggered activity in the brain’s dorsal striatum, a region rich in dopamine, while ingesting the saliva-like drink had no such effect on the pleasure center.

In addition, brain scanning revealed that the aforementioned area was less active in the women who were overweight and in those who carried a particular gene version named Taq1A1, which has previously been linked to low dopamine levels in humans.

The researchers reported that the two categories of women were prone to weight gain during the following year.

Although the study has been conducted on only a few volunteers, its findings are undeniably important to further research into the role that genetics play in obesity. Consequently, doctors could determine whether a person carries the A1 gene version from an early age, thus urging parents to make sure that their children have a healthy diet and get enough exercise, in order to prevent obesity.

Medically speaking, obesity is a condition in which the body has accumulated excess fat to such extent that it may have a negative impact on one’s health. Associated to cardiovascular diseases, diabetes mellitus type 2, obstructive sleep apnea, certain types of cancer and osteoarthritis, obesity has been also found to reduce life expectancy.

The statistical measurement used to determine whether a person is obese or not is called the body mass index (BMI) and is defined as the person's body weight divided by the square of their height. Obesity translates as a BMI of 30 kg/m2 or higher, while an overweight individual’s index ranges from 25 to 29.9 kg/m2 .

Generally, the causes for the medical condition are lack of physical exercise and an unhealthy diet. The treatment includes dieting and exercising more, but if the latter fail to work, doctors can prescribe anti-obesity drugs or, in severe cases, the patient can undergo bariatric surgery, which entails modifying the gastrointestinal tract in order to reduce nutrient intake and/or absorption.

Currently, the Unites States is facing an obesity epidemic, the rates having soared in recent years, raising much concern among health officials. Statistics show that eight in ten Americans aged 25 or older are overweight (approximately 58 million), the number of obese ones having reached 40 million. Moreover, an increase by 76 percent in Type II diabetes in adults aged between 30 and 40 years old has been registered since 1990.