Obese people's appetites 'may be hard-wired in brain'

Obese people may have brains that are hard-wired to find food irresistible, a study has found.

Food craving is associated with different kinds of brain connectivity in those who are obese and of normal weight, the research shows.

Scientists offered buffet-style snacks to 39 obese and 42 normal weight individuals who then had their brains scanned while being shown photographs of the food they had just enjoyed.

The functional magnetic resonance imaging (fMRI) scans showed that in obese participants, looking at the food pictures stimulated connectivity between two specific brain areas.

The first, the dorsal caudate, helps control reward-based behaviour while the second, the somatosensory cortex, is involved in tracking the energetic value of food.

Greater connectivity between the two was positively associated with a desire to consume high-calorie food.

In people of normal weight, the same stimulus prompted more connection between other parts of the brain, such as the ventral putamen and orbitofrontal cortex.

Further research showed that 11% of weight gain in obese individuals over a period of three months could be predicted by the presence of higher dorsal caudate - somatosensory cortex connectivity.

Lead researcher Dr Oren Contreras-Rodriguez, from the University of Granada in Spain, said: "There is an ongoing controversy over whether obesity can be called a 'food addiction', but in fact there is very little research which shows whether or not this might be true. The findings in our study support the idea that the reward processing following food stimuli in obesity is associated with neural changes similar to those found in substance addiction.

"These findings provide potential brain biomarkers which we can use to help manage obesity, for example through pharmacotherapies and brain stimulation techniques that might help control food intake in clinical situations."

The findings were presented at the European College of Neuropsychopharmacology's annual meeting in Amsterdam, the Netherlands.