Satiety is the feeling of fullness and the suppression of hunger for a period of time after a meal. Feelings of satiety can influence appetite and when and how much is eaten next. Appetite controls are an important aspect of maintaining a healthy weight.
Satiety is a vital psycho-biological mechanism whose function is to inhibit intake following the ingestion of a food or a beverage. Satiety is one of the key mechanisms that controls human appetite allowing the adjustment of energy intake to energy needs.
The feeling of satiety occurs in response to a number of signals in the body that begin when a food or drink is consumed and continue as it enters the gut and is digested and absorbed. Hormones detect the amount of fat stored in the body, which will also affect satiety over the long term. Although individuals who are eating will feel the sensation of the stomach filling up, it can take some time after food is first eaten for the full range of satiety signals to reach the brain. Once that occurs and for some time afterwards, a person will experience feelings of satiety.
After an individual eats, a number of factors interplay to stop further food intake. This is known as the Satiety Cascade and was first described in the late twentieth century by Professor John Blundell and his team of researchers at the University of Leeds in the United Kingdom. At the start of a meal, sensory factors such as the taste, smell, and texture of food stimulate eating, but then as eating progresses, people develop a sensory habituation to the ingested foods, which slows eating. Meanwhile, signals from the gastrointestinal tract and the rise in blood sugar levels progressively undermine the motivation to eat and bring eating to an end, a sensation known as satiation. Satiation signals need to be sufficiently powerful to counter the sensory appeal of the food that stimulated eating in the first place. The palatability of a food can decrease satiation, and trials have demonstrated that people will eat a palatable meal that is 44% larger than a neutral or unpalatable meal.
After satiation is reached for the specific sensory characteristics of a particular food, other foods with different sensory aspects may still retain their stimulatory power, so individuals continue to consume food until satiation signals are sufficiently powerful to counter the sensory appeal of all food options. This helps to explain why a person may feel full after eating a savory meal, but then still want to eat a sweet dessert.
Following the end of a meal, satiety occurs when numerous influences contribute to the inhibition of further intake of food for a certain time. The weight, volume, energy and nutrient content, and energy density of the meal determine the intensity and duration of satiety.
Foods that are high in fiber also enhance feelings of satiety as they are digested more slowly and slow the absorption of glucose into the bloodstream. This can prevent fluctuating blood sugar levels in the blood, which in turn can cause hunger pangs and disrupt normal appetite. Healthcare professionals recommended including plenty of high-fiber foods (e.g., wholegrain bread and cereals, beans, pulses, fruits, and vegetables) in the diet.
The addition of energy-dense foods (such as vegetables and wholegrains) with lots of water can increase satiety. Research has shown that soups and stews are particularly satisfying compared to a caloriematched equivalent of drier foods.
Caffeine and capsaicin (the active substance in chilis) have also been found to increase satiety and reduce subsequent energy intake. One study showed that a combination of capsaicin and green tea decreased hunger and increased satiety leading to a significant weight loss over a four-week period.
Chewing food for longer results in less food being eaten during the meal, as does paying more attention to food while eating and minimizing distractions by turning off the TV and other screens.
Many other factors influence eating behavior and may override the body's satiety signals causing the individual to overeat, such as:
Some evidence indicates that calories from liquids are less satiating than calories from solid foods. High calorie drinks, such as sweetened sodas and milkshakes, do not make individuals feel as full as compared with a calorie-matched solid food, which can lead to passive overconsumption of additional food to fill the perceived hunger. In addition, alcohol seems to stimulate appetite in the short term, so drinking alcohol is likely to encourage overeating.
Despite the sophisticated mechanisms that exist to control energy intake, people often continue to eat when they feel satiated or resist eating when hungry. Under optimal conditions, eating should be well connected with hunger and satiation in a way that spontaneously leads to a close match between energy intake and expenditures. The current obesity epidemic suggests that dysfunctions often affect satiety and energy intake.
Some parents worry because their children only pick at meals and eat very little. They want to encourage their children to eat more, but if a child is maintaining an average weight for his or her height and age, parents should not be concerned. Forcing children to eat when they are not hungry can lead to them ignoring their satiety and appetite controls, which in turn can lead to weight problems and possibly obesity later in life.
Conversely, other parents worry that their children overconsume food and do not seem to heed their satiety and appetite controls. Often children who are eating “empty calories” such as junk food and sodas will feel hungry more often and want to continue to eat even after they have consumed more calories than they need for the day, resulting in excess weight gain. Offering healthy food choices such as raw vegetables or fruit with a balancing protein can often curb a child's overeating.
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