The influence of eating speed on satiety
The 20-minute rule is a common way to prevent overeating. The idea behind it is that the stomach only sends an ‘I’m full’ signal to the brain after twenty minutes. The fast eaters among us may have eaten more than they actually need. But what is actually true of that 20-minute rule?
Why is this so important to know?
In 2016, almost half of the adult Dutch population was overweight. In addition, fourteen percent of the Dutch were seriously overweight (obese). A body weight that is too high is undesirable, because it is associated with an increased risk of diseases and psychosocial problems, among other things. One of the most important treatment methods for overweight is dietary advice. This mainly focuses on the composition of the current diet. “What does a person eat?” “How much does a person eat?” From here, a diet treatment plan is drawn up, with the aim of losing weight. This is often effective.
Yet many people experience it as difficult to maintain weight loss for a longer period of time. Scientists, healthcare providers and consumers are therefore regularly looking for new developments and methods to accelerate and/or facilitate weight loss. The 20-minute rule has been around for decades. However, more and more research is now emerging that indeed shows that eating speed is associated with being overweight.
When the interest in eating speed started
Around 1960, a number of researchers suspected that a high eating rate could be a cause of obesity. They thought that fast eaters experienced less satiety. After all, the body was given less time to do its job and to send a satiety signal to the brain. As a result, fast eaters have a greater chance of eating (too) much than slow eaters. Since then, researchers have been trying to find out whether such an ‘obese eating style’ does indeed exist.
Reducing the eating speed
In 2014, a number of researchers made an overview of the available information about eating speed in combination with energy intake (kilocalories) and satiety. In the end, they used the information from twenty-two research articles. This overview has shown with considerable certainty that eating speed has an influence on energy intake. In addition, reducing the eating speed leads to a lower energy intake. One mentioned method that has been used to reduce the eating speed is for example: eating a liquid (using a spoon) instead of drinking (using a straw). Interestingly enough, decreasing the eating rate did not affect hunger pangs during meal cessation or two and a half to three hours later. In other words, lowering your eating speed helps to lower your energy intake without making you more or less hungry.
How Eating Speed Affects Energy Intake
One possible mechanism that explains the effect of eating speed on energy intake is in the mouth. Those who eat fast have food in their mouth for a shorter time and at a lower intensity than someone who eats more slowly. As a result, the person experiences a shorter taste sensation per food unit (per gram or per kilocalorie). As a result, while eating, hunger pangs last longer and satiety lasts longer. Scientific research shows that lowering the eating speed, and thus increasing the taste sensation, leads to a lower energy intake.
In addition, fast eaters take fewer sips, bites and chews per unit of food than slower eaters. Two experimental studies from 2013 and 2014 concluded that increasing the number of sips, bites and chews leads to a lower energy intake. There are indications that this applies to both people with a healthy weight and for people who are overweight.
How eating speed affects satiety
Eating speed also appears to have an influence on the digestive system. When something is eaten, the stomach volume increases, causing the stomach wall to expand. The speed of eating influences the expansion of the stomach wall. Research shows that eating slower ensures that food stays in the stomach longer. In addition, while eating a meal, digestive enzymes (peptides) and hormones (such as CCK, GLP-1 and PYY) are produced. This can also be influenced by the eating speed. Research shows that eating slower causes more hormones to be produced. The combination of increased stomach volume and the production of hormones causes the stomach to empty more slowly and signals (via the vagus nerve and spinal cord) are sent to the brain. As a result, you experience a feeling of satiety and the need for food is inhibited.
20-minute rule: fact or fiction?
Eating speed affects satiety. That is obvious. But it remains to be seen whether the 20-minute rule is correct. “I think the feeling of satiety can occur much earlier than after twenty minutes, but also much later; that depends on a lot of things”, according to Prof. Dr. Kees de Graaf (professor of Sensory Sciences and Eating Behavior at Wageningen University).
What else is known
Regardless of time (eating speed), the consistency of the food you eat or drink can affect satiety. For example, research shows that apple juice (a liquid food) is consumed ten times faster than an apple (a solid food). As a result, apple juice is less saturated than an apple. The same goes for other fruit juices, which are less satiating than eating whole pieces of fruit.
Furthermore, research shows that the type of nutrient you eat can be more or less satiating than another nutrient. For example, proteins (which mainly occur in meat, fish and dairy products) have a greater satiating effect than carbohydrates and fats.
Finally, research shows that a varied menu leads to a higher food intake than a single dish. This has to do with “sensory-specific satiety” or “change of food makes eating”. In short, this means that our need for one type of taste may be inhibited (it no longer satisfies us), while we still crave another type of taste. We probably all recognize that we feel full after the main course, but that we still have an appetite for dessert. A varied menu therefore ensures that we feel psychologically less satisfied, so that we eat more.
Conclusion
Eating more slowly leads to a lower energy intake. Reducing the eating rate (for example, through mindful eating) could therefore be a good additional method for achieving weight loss or weight maintenance. In addition, it remains important to pursue a healthy diet, in which attention is possibly paid to the correct consistency, type and variety of foods.
Sources:
- Bolhuis DP, Lakemond CMM, et al. (2011). Both Longer Oral Sensory Exposure to and Higher Intensity of Saltiness Decrease Ad Libitum Food Intake in Healthy Normal-Weight Men. American Society for Nutrition
- CVM. Center for Mindfulness. What is Mindfulness.
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Public health care.info. Overweight→Numbers & Context→Current situation.
