Obesity is associated with a number of health complications. One more has been added to the list - change in brain chemistry.

A new research by the National Institutes of Health Clinical Center showed that obese people are vulnerable to environmental food signals compared to those with normal weight. It is important to note this as the difference in brain chemistry can lead to habitual eating that is less rewarding.

For the study, the researchers assessed data of 43 men and women with different amounts of body fat.

The findings of the research showed that obese people mostly had higher dopamine activity in the habit-forming region of the brain as opposed to those with normal weight. They also had less activity in the brain region controlling reward.

According to the researchers, these brain differences worsen the risk of obese individuals to overeat and experience less enjoyment while eating.

"While we cannot say whether obesity is a cause or an effect of these patterns of dopamine activity, eating based on unconscious habits rather than conscious choices could make it harder to achieve and maintain a healthy weight, especially when appetizing food cues are practically everywhere," lead researcher Kevin D. Hall, Ph.D., a senior investigator at National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), said in a press release.

"This means that triggers such as the smell of popcorn at a movie theater or a commercial for a favorite food may have a stronger pull for an obese person - and a stronger reaction from their brain chemistry - than for a lean person exposed to the same trigger."

Dr Griffin P. Rodgers, NIDDK Director, said that the findings of the study show the complexity of obesity and explain how people with different amounts of body fat process information about food. "Accounting for differences in brain activity and related behaviors has the potential to inform the design of effective weight-loss programs."

The findings were published in the journal Molecular Psychiatry.