Researchers claim that our junk food culture has led the brain's pleasure centre overpower the chemicals in the stomach which satiate the hunger pangs, the 'Daily Mail' reported.
Throughout human evolution, these two systems have co-existed to control fullness and maintain a healthy lifestyle but now that we are surrounded by sugary desserts and junk food, the balance is disturbed.
"The feeling of satiety, which is a central component of this system, is triggered when the stomach is stretched beyond a certain threshold. At this point, chemical and neural signals are sent to the brain that instructs it to stop eating," leading researcher Dr Nora Volkow, director of the National Institute on Drug Abuse in Maryland said.
"This mechanism has evolved over hundreds of thousands of years of human evolution, and it has served us well in an environment that wasn't particularly plentiful in terms of food, let alone foodstuffs with high-caloric content," Volkow said.
The two systems constantly talk to each other and long co-existed in harmony, keeping calorie intake,which in turn keeps the weight in check.
When one consumes desserts and junk food, the balance can be disturbed, leaving the signals from the full stomach unable to over-ride the powerful craving for food produced by the brain.
Those who want to exert more self-control should try saying 'no' before temptation is placed in their way.
Barbara Sahakian, a Cambridge University professor who has run eating disorder clinics, said the thought of a different taste can reawaken appetite.
"That's the big dessert effect we all experience. Maybe we can't even get through our whole meal, we eat three-quarters of the main course and can