The length of time you spend chewing food may be at least as important as how full your stomach is when it comes to how much you consume, according to a new study by Nestlé.
Scientists from the Nestlé Research Center, in collaboration with Wageningen University in The Netherlands, carried out what is thought to be the first examination of the effect of simultaneous oral and gastric stimulation on satiety. The results suggest the time people spend chewing may be an important factor in determining their energy intake. This supports earlier research suggesting drinks may not be the most effective format for developing food products for satiety.
In the Nestlé study, participants were monitored on five non-consecutive days. They were asked, in random order, to chew but not swallow food for one or eight minutes while having different amounts of the same food infused into their stomachs. In a control condition, participants did not receive any food and were not given any food to chew.
Half an hour later, all participants were given a meal and invited to eat as much as they liked until they were comfortably full.
The study found that when participants chewed food for one minute, they ate the same amount as they did on an empty stomach, regardless of how much food had already been infused in to their stomach.
However, when participants chewed for eight minutes they consumed significantly less than they did on an empty stomach.
"Our findings suggest longer oral-sensory stimulation may be an important factor in lowering energy intake," said Dr Alfrun Erkner, a Nestlé Research Center scientist involved in the study.
"This doesn't necessarily mean specially-designed nutrition beverages can't have a satiating effect, but that products that provide increased oral stimulation could be more effective. "Follow-up studies are needed for a better understanding of the impact of the interaction of oral and gastric factors on eating behaviour," she added.
The study involved 26 fit young men of healthy weight. On one day they chewed cake for one minute without swallowing it while receiving 24g of cake in a 100ml solution through a nasogastric tube.
On another day they chewed cake for one minute without swallowing it while receiving 24g of cake in an 800ml solution. On two other days they chewed cake for eight minutes without swallowing it while receiving either 100ml or 800ml of the same solution. On another day they did not chew any cake or receive any liquid, but wore a nasogastric tube. This was the control condition.
The participants rated their appetite and hunger immediately before and after the tests, then 15 minutes afterwards and then again before and after the meal. Participants were not allowed to eat any food or drink any energy-containing beverages for two and a half hours before the tests began. They were also asked to avoid intensive physical exercise throughout the study.
Nestlé ultimately aims to use research of this kind as the scientific basis for developing foods that could help consumers feel satisfied and less hungry between meals. The study, published in the scientific journal Obesity, is part of Nestlé's ongoing research into the factors that help people feel satiated.
This includes studies examining the effects of various protein sources on energy metabolism, satiety and glucose control and the complex signals sent by the gut to the brain.
