Reporter 409, 3 November 1997


Feeling hungry? Leeds psychologists pose the 64,000 calorie question

If you are on a bus and you hear an electronic bleep, followed by the sight of somebody tapping into what looks like a personal organiser, then you could have stumbled across one of the University’s major research projects. A team of psychologists, led by Professor John Blundell, are exploring the tastes and appetites of Leeds people.

Every day there are people answering questions like ‘Are you feeling hungry?’ as part of a series of studies of eating patterns and appetite control. Researchers in the University’s psychology department hope that revealing people’s eating habits will make it easier to target campaigns for more healthy diets. The bleep is their reminder to type in an answer.

Research has shown that:

- Obesity is more common among those with high fat diets;

- People with high fat diets are more likely to smoke and drink beer;

- High fat consumers cross class and age barriers;

- Exercise does not make you hungry.

Measuring feelings of hunger on the portable Electronic Appetite Rating System (EARS) – a computerised tool developed by the University – is only one aspect of a wide-ranging series of multi-disciplinary studies involving a team of researchers made up of psychologists, nutritionists, physiologists, pharmacologists, dietitians and sports scientists. Information keyed in by those taking part is uploaded into computers at the psychology department to be analysed alongside other data from the study of people’s habits both at home and in the laboratory.

The Leeds High Fat Study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), is one of the most in-depth studies of appetite control ever undertaken. Around 1,800 randomly selected people took part over three and a half years, willingly supplying details on everything they eat from burgers to blackberries.

Professor John Blundell explains: “We sought people who could be identified as particular phenotypes, that is either high fat or low fat consumers, and we found that the high fat group differed from low fat consumers in a number of ways. First, by definition, they consumed large amounts of fat. Second, they consumed different types of foods. Their diets were high in meat, meat products and dairy products, and rather low in cereals, fruit and vegetables, bread, white meat, and white fish. The low fat group were the opposite.”

Not surprisingly, therefore, there was a higher frequency of obesity among those within the high fat group than the low fat consumers. It was also discovered that the two groups tended to have different lifestyles. High fat consumers were more likely to be smokers and heavier drinkers, while more than half of them skipped breakfast. Ironically, missing breakfast did not result in them eating less – they more than made up for it later in the day.

Interestingly, there was some evidence that people had changed from the high fat to the low fat group in the last few years, in response to health messages about heart disease, cancer, cholesterol and so on.

According to Professor Blundell: “The study tells us how people on high fat diets organise their lives. The importance of this is that, if we are to make interventions to change high fat consumption, then we actually need to know this information so that we can target such interventions more effectively.”

A separate Agro-Food Link Project, funded by the Ministry of Agriculture, Fisheries and Foods, found that it was relatively easy to consume worryingly large amounts of fat – particularly when such foods are palatable, heavily promoted, and a major part of our modern culture.

While we have defences against losing body weight, we have few mechanisms to stop us putting it on. “Our ancient physiological system is being overwhelmed by cultural developments and changes in the food supply,” points out Professor Blundell.

This phenomenon of our age is labelled ‘passive overconsumption’. But far from passive are the volunteers taking part in a related study, funded by BBSRC, into physical activity and diet composition. At a specially-equipped lab in the psychology department, they are put through their paces on a treadmill and two exercise bikes. The expired air is collected and measured using a calorimeter to see how much energy they use. The idea is to examine the links between eating and exercise.

Research fellow Dr Neil King, who trained in sports science and physiology, says the study has dispelled two common myths about exercise and food. First, physical activity does not make you eat more. Second, if you ‘reward’ yourself for taking exercise by going out afterwards for a few pints or a cream cake, you will undo all the good you have done.

“We’ve found an uncoupling of energy expenditure and energy intake,” he explains. “People come in and have intensive exercise sessions on three successive days, yet they do not eat more and they do not feel hungrier. On the other hand, you can’t reward yourself afterwards.”

Professor Blundell concludes that the key to a healthier lifestyle is exercise combined with a low fat diet. A runner himself, he tries to practice what he preaches.

The research has already indicated physiological differences between the high and low-fat phenotypes and the next stage is to work with molecular biologists to search for genes which might be markers for the high fat groups.

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