Anorexia nervosa — an eating disorder that makes people obsessive about their weight — could alter the brain circuits and impact its taste-reward processing mechanisms, especially for sugar, a study has found.

While most people like sweet tasting things, those with eating disorders associate the taste with weight gain and try to avoid it.

The study showed that the brain activation among the anorexia group was inversely connected with any pleasant experience of eating sugar.

Those who are already worried about shape and weight become even more concerned. And a strong response that says “feed me” might be overwhelming and trigger more food restriction instead of eating.

It is because a brain reward circuit associated with the dopamine becomes more active but also triggers anxiety.

“When you lose weight, your brain reward response goes up but instead of driving eating, we believe it elevates anxiety in anorexia nervosa, which makes them want to restrict more. This becomes then a vicious cycle,” said lead author Guido Frank from University of Colorado School of Medicine in the US.

For the study, published in the journal JAMA Psychiatry, the team examined from over 100 participants including 56 female adolescent and young adults with anorexia nervosa aged between 11 and 21 years and 52 healthy control participants.

The team also found that higher brain response lead to higher harm avoidance — an anxiety measure for excessive worrying and fearfulness — in those with anorexia nervosa. In these patients, it pushes the drive for thinness and furthers body dissatisfaction.

“An enhanced dopamine reward system response is an adaptation to starvation. Individuals vulnerable to developing anorexia nervosa could be particularly sensitive to food restriction and adaptations of reward response during the development period,” the study noted.