IFT: food cravings could be key to obesity
29/06/2006- The role of food craving must be properly investigated if we are to successfully develop measures to counter the current obesity crisis, said Marcia Levin Pelchat from Morell Chemical Senses Center in the US.
Speaking at this week's IFT conference in Orlando, she said that the failure of diets can often be linked to craving.
"If you talk to a person who tried to diet and stopped, they'll often say something like: 'It fell apart at that Christmas party. I saw those chocolates, I started early, and I couldnt stop.'
"This might be a way in which craving plays a role in diet failure."
Pelchat said that craving is defined as an intense desire to eat a particular food. The specificity is important, as this distinguishes it from hunger. It is a sensory memory that has to be matched in order to achieve satisfaction.
"Cravings are very common, with chocolate and pizza topping the list. But why? 95 per cent of craved foods are high in fat, but is this a critical factor? More research is needed on this."
But one thing is clear gender pays a critical role in craving. For young women, 60 per cent of the foods craved are sweet, while 40 per cent are savoury. These figures are reversed for older and young men.
"These differences are very robust," said Pelchat.
She also questioned the widely-held assumption that cravings occupy a nutritional need. "You know - craving crisps when you have a cramp, or chocolate when you need potassium."
Pelchat and her team were therefore interested to find out whether boredom would be enough to trigger cravings. Together with colleagues at Morell, she fed volunteers a monotonous diet, and examined brain scans to see what was happening.
"In our studies, we found that nutritional deprivation was not necessary for cravings to happen," she said. "We found that neurotransmitters have similar effects on desire for foods and drugs.
"All participants in our study experienced cravings when imagining the liked food, but no one experienced cravings when imagining the monotonous diet. The structures of the brain that grant reward are linked to memory."
The team therefore discovered a parallel in the brain between drug addition and food cravings. A major difference, as Pelchat pointed out, is that food is necessary for life, while drugs of abuse hijack the brain mechanisms and stimulate them stronger than natural rewards.
"But these parallels could be useful in how to treat people that over-eat," said Pelchat. "Many studies off obesity are focused on controlling hunger, while treatments for drug abuse focus on craving and impulsivity. Given the parallel, it might perhaps make sense to treat obesity in the same way."
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