Posted on Thursday 24th April 2008
Thinking about the last meal you had could significantly reduce the desire to snack, research at the University of Birmingham has revealed.
Psychologist Dr Suzanne Higgs took a group of women students who had had a set lunch and asked them to take part in a biscuit taste test – the women were unaware of the real motive behind the study.
Before the biscuit taste test began, half the participants were asked to give a detailed written description of their meals. The other half were asked to describe their journey to campus.
After the contrived taster session, all the women were invited to help themselves to as many biscuits as they wanted.
Dr Higgs found that the women who had been asked to recall their lunch ate fewer biscuits than those who had recounted their journeys.
The difference in biscuit consumption was more noticeable as more time elapsed after eating. Dr Higgs explains: “The women who had been asked to recall their lunches and who took the taste test after three hours showed significantly reduced appetites compared to those who had detailed their journeys. This may be because after just one hour, the memory of eating lunch was still vivid enough to affect all the women’s appetites.”
The influence of learning and memory on eating behaviour is at the core of Dr Higgs’ research. Whilst the results appear to contradict the generally held belief that thinking about food actually triggers the appetite, Dr Higgs suggests that this could be down to the fact that participants were asked to recall the meal they ate most recently, rather than food generally.
The ability of memories of a prior meal to reduce appetite may depend on information processing by the hippocampus, an area of the brain known to be important in learning and memory and decision-making. This idea is in line with other evidence that people who are unable to remember that they just ate, because of hippocampal brain damage, will eat two or three lunches on the trot if they are offered them one after another.
It would be fascinating to find out how people without a neurological condition differ in their ability to recall a recent meal and whether this is related in any way to how much they eat in the longer term and their body weight.
Having studied the effects of boosting memory, Dr Higgs is now planning to look at how the deliberate disruption of memory impacts "I am now following up with a study that examines the theory in reverse, so whether disrupting people's memories whilst eating - by watching television whilst eating, for example - causes an increase in appetite."