People may consume fewer calories over the course of a meal when they eat slowly, a new study suggests. But it's not clear if that strategy works as well for people who are overweight or obese as it does for their slimmer peers.
Past studies have come to mixed conclusions on whether how fast people eat affects how much they end up eating, Meena Shah said. She led the new research at Texas Christian University in Fort Worth.
"In addition most of the previous studies have not compared the effect of eating speed on energy intake in normal weight or overweight and obese subjects," Shah said in an email.
Her team's study included 35 normal weight people and 35 who were overweight or obese.
All of the participants were asked to eat the same vegetarian pasta meal on two different occasions. The first time around, people were asked to eat either quickly or slowly, based on a random assignment. A few days later, they were given the opposite instructions.
On fast eating days, the researchers asked participants to eat as quickly as possible without feeling uncomfortable - as though they had time constraints. They told them to take large bites, chew quickly, not put utensils down and not pause between bites.
On the slow eating days, they told people to eat as if they had no time constraints. They instructed them to take small bites, chew thoroughly and put their fork or spoon down and pause between bites.
The researchers secretly measured how much food participants ate by weighing their plates after meals.
Normal weight participants consumed 88 fewer calories during the meal when they ate slowly, on average - 805 calories compared to 893 calories during the faster meal. That was a clear change.
Overweight and obese people consumed 58 fewer calories during the slow meal - 667 calories versus 725 calories. But that difference could have been due to chance, according to findings published in the Journal of the Academy of Nutrition and Dietetics.
Shah believes the overweight and obese participants may have eaten less because they felt self-conscious during the study.
Participants in both groups drank more water when they ate slowly and felt less hungry at the end of the meal.
"This study provides new data that supports the hypothesis that how you eat may have an effect on appetite and influence body weight," James Hollis said in an email.
Hollis, from Iowa State University in Ames, was not part of the new research.
"This is an interesting study and any method that reduces food intake by 8-10 percent at a single meal would be useful," he said. But more studies are needed to show whether eating slowly could help people manage their weight, Hollis said.
His own recent report published in the same journal found people tended to eat less when they were instructed to chew more before swallowing.
"It has not been adequately determined how slow is slow enough or what is the minimum reduction in eating speed required to have an effect on food intake," Hollis said.
He said it's also not clear if all of the techniques - chewing slowly and more times and taking more pauses during meals - have the same effect on how much people eat.
"I would recommend slowing the speed of eating because it may reduce the amount of food consumed as well as lead to a greater degree of fullness or less hunger later on. It is not necessary to time the meal, though," Shah said.
"Eating in my opinion should be an enjoyable experience without having to check the time," she said.