It's time to eat and we start with a salad. We continue with two steaks of meat and chips. What we have eaten is enough to get to the night, but we are still hungry, we are not yet satiated. We get up and make two fried eggs and more potatoes. As we are still hungry we eat an apple, a banana and a piece of cake. Now yes, we are already satiated! The next day, at the same time, we can hardly finish a salad. The question is clear: What factors influence how much we eat?
If we pay attention, we usually eat the same amount of food every day, however, there are times when we are less hungry and days when we would eat the rest of the diners. How much do we eat? What determines the amount of food we eat? Why sometimes we just have a salad and a steak and other days we need to eat much more? Throughout the article some of the most relevant theories that have been developed to explain the amount of food we eat will be presented.
- 1 How much we eat: Signs of satiety
- 2 False intake
- 3 The appetizer effect and satiety
- 4 Social influences in relation to how much we eat
- 5 Specific sensory satiety
How much we eat: Signs of satiety
When we are full and we can no longer say that we are satiated. As defined by John Pinel (2006), "The state of motivation that stops us from eating food when there is still food left is satiety"The satiety signals are produced by the presence of food in the intestine and the beginning of the entry of glucose into the blood. In this way, through these signals, the consumption of the rest of food is inhibited. These signals depend of two factors, on the one hand of the volume and on the other of the nutritional density of the food, that is, the calories per unit volume.
The theory of false intake states that satiety signals from the intestine and blood are not necessary to stop eating. Different laboratory investigations have proven this hypothesis. The false intake is that a subject chews and swallows the food but instead of going from the esophagus to the stomach, the food is expelled out of the body through a tube that has been previously implanted.
In this experiment conducted by Weingarten and Kulikovsky in 1989, two different types of food were administered to two groups of rats. They supplied food to a group that they had already tried. At the beginning, the consumption was the same as when the intake was real, but after a few days they started eating more. The other group was given unknown food and ate more from the beginning.
The authors concluded that, to a large extent, the amount of food we eat depends on the previous experience of the specific effects that take place after the food intake. Thus, the intake would not be related to the immediate effect that the food would produce on the organism.
The appetizer and satiety effect
When we have the possibility of having a snack before eating, sometimes we can not eat it for fear of being satiated before the main meal. Many times we have heard the famous phrase: "I will not itch more than later I will not be hungry". However, according to the theory of the aperitif effect, the opposite can happen.
This theory defends that eating small amounts of food before the main meal can increase hunger instead ofdecrease it. According to this theory, the increase in hunger would be produced because the small amount of food consumed would cause responses of the cephalic phase. It is a preparatory phase before eating. It usually starts when you smell, see or just think about food. The cephalic phase comes to an end when food begins to be absorbed by the bloodstream.
Social influences in relation to how much we eat
In 1992, Redd and de Castro concluded that the feeling of satiety depends on whether you eat in company or alone. The authors found that people eat 60% more when they eat with other people. However, food intake can also be reduced when more people are present. Although in this case the reasons are related to not wanting to seem too gluttonous or to maintain the ideal of thinness.
Specific sensory satiety
At this point the call stands out cafeteria diet. It is a varied diet in very tasty foods. Rogers and Blundell (1980) conducted an experiment with rats with which they revealed the effect of this type of diet. A group of rats were given bread with chocolate in addition to their normal diet. What happened? The caloric intake shot up 84% more and the average weight had increased 49%.
The effects produced by the cafeteria diet on the amount of food we can eat reveals that satiety can be produced in great demand for flavor. This is, as we eat a single food or a single plate, the positive incentive value of all foods drops, but that of that food falls completely. On many occasions, we have tired of eating the same thing, however, when they have brought us something new, we have eaten again.
Specific sensory satiety seems to have two adaptive effects. On the one hand, it promotes a varied diet composed of different foods. If this were not the case, we could always eat our favorite food and we could lack the necessary vitamins and nutrients. On the other hand, this encourages animals to eat in large quantities when they have the option of choosing different foods. In this way, they take advantage of times of abundance.
- Blundell, J. and Rogers, P. (1980). Effects of anorexia drugs on food intake, food selection and preferences and hunger motivation and subjective experiences. Appetite, 1 (2), 151-165.
- Pinel, J. (2006). Biopsychology. Madrid: Addison-Wesley.
- Redd, M. and de Castro, J. (1992). Social facilitation of eating: effects of social instruction on food intake. Physiology and Behavior, 52 (4), 749-754.
- Weingarten, H. and Kulikovsky, O. (1989). Taste-to-postingestive consequence conditioning: is the rise in sham feeding with repeated experience a learning phenomenon? Physiology and Behavior, 45 (3), 471-476.