The hardness of food is a much bigger factor in the feeling of fullness, or satiety, than its sweetness, discovered Marlou Lasschuijt, a PhD candidate at Human Nutrition. By changing the texture of foods, producers could therefore induce people to eat less of them.
‘We know from previous studies that satiety is affected by the sweetness of food and how much you chew it,’ says Lasschuijt. ‘But the separate of these two factors wasn’t clear.’
To find this out, the researcher served 58 test subjects four different gels with different textures and degrees of sweetness. ‘The participants had fasted beforehand and then they were given a measured quantity of food that matched their body size, so they were all equally full at the start of the test. Then they were each given one of the gels, and they could eat as much of it as they wanted. The number of chewing movements they made was recorded too.’
The participants ate 21 percent less of the hard food than of the soft food, whereas they all reported feeling equally full. Strikingly, the sweetness of the gels had no influence on how much people ate. Possibly the sweetness did not vary enough, speculates Lasschuijt. In earlier tests people proved not to like ultra sweet gels as much. ‘For our study it was important that participants liked the taste of the four gels more or less equally.’