Some individuals, hard as they try, may still fine it difficult to moderate the quantity of food they eat. At least one reason for this can be that they are eating foods that aren’t particularly satisfying. Two factors that affect the sating effects of food are the glycaemic index (the speed and extent to which a food releases sugar into the bloodstream) and it’s protein content. In short, the lower the glycaemic index and the higher the protein content, the more satisfying a food is. On the other hand, a diet made up of relatively high GI and low protein foods (a typically carbohydrate-rich diet) can be distinctly unsatisfying, and this can drive individuals to overeat.
It’s not just what we eat but how we eat it that can determine how satisfying food is to us. In 2007 I blogged about a study in which women were asked to eat a pasta-based meal under two distinct conditions. At one sitting, they were asked to take small bites and chew each one 15-20 times. At another sitting, they were asked to eat as quickly as possible. The women ate until they were satisfied. Compared to the faster-eaters, the women instructed to take their time and chew thoroughly consumed about 70 calories less. Not only that, but these women felt more satisfied immediately after the meal and an hour later.
On the back of this study I was interested to read about a similar piece of research that has recently been published on-line in the American Journal of Clinical Nutrition . It took 22 individuals and measured their intake of a test food (semi-solid chocolate custard) under a number of different circumstances. For example, in one test, individuals were instructed to consume the custard using relatively small bites (5 grams of custard). At another time, they were instructed to take larger bites (15 grams). In both of these settings, test subjects were also asked to process the food in their mouths quickly (3 seconds before swallowing) and slowly (9 seconds). In all test settings, individuals were instructed to eat as much as they wanted and to stop when pleasantly satisfied.
One notable finding from this study was that less was eaten when the subjects took small bites compared to large bits. Average intake was about 100 calories less (about a 23 per cent calorie reduction).
Also, though, the longer the oral processing time, the less was eaten too (longer processing time was associated with a reduced intake in the order of 70 calories for small bite sizes and 50 calories for larger bite sizes).
What this study suggests that taking small bites and chewing them thoroughly (to increase oral processing time) may lead to a natural reduction in the amount of food consumed during a meal. It would be nice to see this study repeated with, not chocolate custard, but real food (e.g. meat and vegetables) to see how applicable these study results might be to the real world.
However, it is also worth bearing in mind that there is other evidence which supports the concept that what happens in the mouth can have a bearing on the satisfaction derived from food and how much of it is eaten. Research has found that eaten food is more satisfying than food just infused into the gut. Taking time to savour food properly might turn out to be quite powerful weapon in or efforts to prevent the overconsumption of food.
1. Zijlstra N, et al. Effect of bite size and oral processing time of a semisolid food on satiation. Am J Clin Nutr 10th June 2009 [epub ahead of print publication]