Cognition controls consumption

Cognitive behaviour plays a major role in some people’s consumption patterns, according to the latest research findings. For example, some individuals may see 'low fat’ labels on foods as a “licence to overindulge”,​ said Rick Mattes, Professor at the Department of Nutrition Science and director of the Ingestive Behavior Research Center at Purdue University in the US.

Mattes made his remarks during a presentation on the effect of food 'form’ on appetite, energy intake and metabolism at a conference on nutrition organised last month by Leatherhead Food Research.

He described recent research, which showed that some people had a completely different satiety response when they believed that the food they were eating became a solid in the gut rather than becoming a liquid. This was despite the fact that, in the trials conducted, participants were actually consuming the same juice product (solid and liquid), which either became or remained a liquid in their stomachs.

‘Altered in their mind’ ​

“The sensory property was actually altered in their mind,”​ said Mattes. “Hunger stayed higher in the liquid to liquid​ [experiment] relative to the solid to solid and that translated into different daily energy intake. They ate less during those days when they thought it was going to be a solid in their stomach than the days when they thought it was going to be a liquid in their stomach.”​

However, these perceptional changes also fed through into physiological responses, remarked Mattes. Consequently, when trial participants thought they were consuming liquids that remained liquids in their stomachs, the contents of their stomachs emptied more quickly than when they thought they were solid. A similar effect was found to occur on appetite changes to stimulating hormones, he added.

“Basically the entire profile of the ingested process and the digestive process were altered just by expectations of the food and all the physiology was in the direction that would have predicted that the beverage would be viewed as less satiating,” ​said Mattes.

‘Oral sensory signal’​

Mattes also presented results to show that similar perceptional changes could be achieved by altering how foods are perceived in the mouth taste and mouthfeel so called “oral sensory signals”​ on physiological effects such as fat oxidation. But people adapted to this phenomenon, reported Mattes, so that it had a greater effect on people who didn’t have this oral stimulus so frequently.

It is well known that chewing behaviour affects absorption of nutrients such as fat, so that the more people chew the greater the absorption. But research also shows that the effect of chewing is influenced by how different foods are processed, said Mattes.

For example, roasting peanuts and almonds makes them more brittle so that when they are chewed they tend to fracture into smaller pieces, which makes their nutrients more bio-accessible. However, chewing responses differ between lean and obese individuals, he added, with the latter being stimulated to eat more.