Title: ENDO: Tasting Food May Cause Elevated Brain Activity in the Obese

"ENDO: Tasting Food May Cause Elevated Brain Activity in the Obese"


By Mike Fillon NEW ORLEANS, LA -- June 18, 2004 -- The activity of
some brain regions is especially high in obese individuals compared to the
nonobese, in particular those regions involved in generating emotions in
response to and in recognition of the taste of food. The new findings,
reported here on June 16th at the 86th Annual Meeting of The Endocrine
Society, could help in the understanding of why some people overeat, the
researchers say. According to lead author Angelo Del Parigi, MD, Clinical
Diabetes and Nutrition Section, Phoenix Epidemiology and Clinical Research
Branch, National Institutes of Health, Phoenix, Arizona, it is believed that
for some individuals there is some irresistible force driving them to eat
more food than they need to, ultimately increasing their risk of becoming
obese. Dr. Del Parigi says there are reasons to think that the culprit may
be emotions -- especially pleasure -- derived from the sensations of taste,
smell and texture, for example, generated by the passage of food through the
mouth. Dr. Del Parigi and colleges used positron emission tomography imaging
to measure changes in regional cerebral blood, a marker of neural activity,
in 21 obese and 20 lean subjects before and after they fasted for 36 hours
then tasted a liquid meal (Ensure Plus). The obese subjects were 10 males
and 21 females, and had a body mass index (BMI) greater than 35 kg/m[2.
Controls were 10 males and 10 females, and had a BMI below 25 kg/m2.
Activity of some brain regions, especially those involved in
generating emotions to and recognition of the taste of food, was especially
elevated in obese subjects. "Abnormally high activity in the insular cortex
region of the brain, which responds to the sensory experience of food, may
put people at an increased risk for obesity," Dr. Del Parigi explained.

Differences in changes to regional cerebral blood flow (rCBF) were
seen in several brain regions (middle dorsal insula and cerebellum,
precuneus, posterior cingulate, and temporal and orbitofrontal cortices) in
obese as compared to lean subjects. The group difference in the insula was
observed in both men and women separately. This activity is only partially
explained by the elevated glycaemia and high level of disinhibition (i.e.,
the susceptibility of eating behavior to emotional factors and sensory cues)
that characterise obese individuals, the researchers note.

Using multiple regression analysis, the researchers found that
percentage of body fat (P =.04), glycaemia (P =.01), and disinhibition (P
=.07) were associated with changes in rCBF measured in the insula (R2 =.45).

They do not know if this activity is caused by a particular
sensitivity to food stimuli in the brains of obese individuals or if another
aspect of being obese changes the way the brain responds to any stimulus.

The researchers believe that abnormal activity in the insular cortex
may represent a marker of increased risk for obesity and, therefore, that
continuing to study the human brain and its response to food will eventually
answer why so many people eat more than they should and are so susceptible
to gaining weight.


[Presentation title: "Taste and Obesity: A Positron Emission
Tomography (PET) Study of the Brain Regions Affected by Tasting a Liquid
Meal after a Prolonged Fast." Abstract #OR19-4]