The satiety index (IS) is an index describing the level of satiety after eating a portion of a food product with a certain caloric value. It was developed as a helpful tool in the fight against overweight and obesity. Choosing food with a high satiety index is designed to help you stick to a low-calorie diet and prevent hunger pangs.
What is the satiety index?
The Satiety Index (IS) is a food index that shows how long a food will satisfy your hunger. It was created by the Australian researcher – Dr Susanna Holt from the University of Sydney, who deals with human nutrition at the Department of Biochemistry.
The idea for the satiety index comes from a hypothesis that almost everyone has felt – that different foods with the same caloric value will satiate for a different period of time.
Dr Holt and her colleagues ranked foods according to their effect on satisfying hunger. The aim of the researchers was also to link the nutritional value of products and the feeling of pleasure when consuming them and the persistence of the feeling of satiety. The results of the research were published in the scientific journal European Journal of Clinical Nutrition as early as 1995, but it doesn’t get much interest, until recent years. This is probably related to the progressive plague of obesity, which is becoming increasingly difficult to control.
Why do some foods fill you more than others?
Feeling full long after eating is related to the protein, fibre and water content. Protein-rich foods such as meat, eggs and fish suppressed hunger at least 1.5 times longer than white bread. Conversely, sweets, such as croissants, satiated only half as well as bread.
A study on the satiety index has shown that we are unfairly afraid of eating potatoes. Boiled in water, they are very filling, contain a lot of fibre, provide vitamins and do not make you gain weight. It is worth paying attention to the fruits which were assigned a high satiety index in the study. They meet two important criteria – they contain a lot of fibre and water, but also simple sugars. Within two hours, satiety coming from fruits is high, but after this time it drops sharply and you feel a strong hunger associated with a drop in blood glucose.
It should be noted that the study focused on short-term satiety – felt up to 2 hours after eating.
What determines the feeling of hunger and satiety
The feeling of hunger and satiety are very complicated mechanisms that depend on many factors and signals transmitted between the digestive system and the brain. Satiety is not so much related to the number of calories eaten as to the volume of meals. The stretching of the stomach walls is a signal that you are full. The feeling of satiety is also strongly related to the taste of the products.
The tastier the food, the shorter satiety it will give. This probably has to do with the fact that we consider the most delicious meals as those rich in fat and sugar. Protein and starch content has been associated with lower palatability of the products. So is a large portion of food and the water content in it.
Fat is a filling component of food because it delays stomach emptying, but it is very caloric – more than twice as high as protein and carbohydrates. Therefore, servings of foods rich in fat, providing 240 kcal are relatively small and fill the stomach to a small extent. Simple sugars are known to cause large fluctuations in blood glucose and insulin levels, which are associated with the feeling of very strong hunger.
Analyzing the dependence of the feeling of satiety on various factors, it was found that
- high-fat content is associated with a low satiety index,
- high protein, fibre and water content is associated with high IS
- high sugar content is associated with low IS
- greater satiety is associated with a larger portion (in term of volume) of the product
- low satiety is associated with a highly rated palatability of food