What affects satiety?

Satiation and satiety are complex processes that determine how much we eat. Understanding what affects satiety can help us ensure we are eating the amount of food that matches our needs.

Satiety vs satiation

Satiation and satiety are terms that are often used interchangeably. While both processes/mechanisms relate to eating and fullness, they actually happen at different times (1, 2).

“Satiation was defined as a set of complex processes that progressively inhibit the motivation to eat during an eating event” (3). Satiation develops while we eat and causes us to stop eating (1, 2).

“Satiety is the inhibitory mechanism that takes place after the end of an eating episode and prevents the return of hunger for a variable duration” (3). Satiety is the feeling in between meals that prevents us from reaching for more food (1, 2, 4).

Both satiation and satiety depend on sensory, cognitive, postingestive (i.e. after food intake) and postabsorptive (i.e. after nutrient absorption) processes (1). In an ideal scenario, satiety follows satiation and regulate food intake so that the energy we take in matches our requirements to the last significant figure (3).

What affects satiety?

Although is tempting to believe satiation and satiety are biological processes controlled solely by mechanical and chemical signals, the truth is a lot more complex.

Hormones and peptides

There are a number of gut peptides that regulate appetite and satiety, including:

1. Ghrelin: stimulates appetite
2. Cholecystokinin (CCK), glucagon, glucagon-like peptide 1, peptide YY, amylin, and others: suppress appetite (2, 5)

In addition, an increase in body fat will result in the secretion of extra insulin and leptin, which increase sensitivity to CCK and amylin. This means that mechanistically, gaining fat should result in a reduction of food intake (5).

Expectations

People tend to choose meal size based on how much we think it will fill us up. In fact, expected satiety turns out to be more important for us when choosing portion size than hunger and how much we think we’ll like the meal (6).

Most of us have pre-conceived ideas of which foods will produce greater satiety. In general, we tend to rate non-energy dense food (e.g. potatoes) as more satiating that energy dense foods (6, 7). This may indicate that the volume of consumed food is more important than its energy content (7).

Expected satiety is, in part, learned. Therefore, people tend to think familiar foods will be more satiating than new (to them) foods. Expected satiety and satiation can change over time based on visual and sensory cues and information such as labelling. Expectations are learned over time (6).

In addition, how much food people think they are consuming makes a difference in their perception of satiety (3, 6, 7).

Food consistency/texture

Food consistency has an effect on expected and perceived satiety. For example, people will generally think thicker yoghurt is more satiating than thinner one and will report less hunger after eating it (7). When tested, foods with higher thickness or viscosity tend to suppress appetite better than less thick or viscous foods (2, 6).

Solid and semi-solid food also suppress appetite more than liquid foods (2).

Scientists have also suggested that foods which contain multiple different textures (e.g. crunchy + creamy + chewy in one dish) may decrease hunger (2).

Finally, the addition of air (e.g. in a soufflé) may correlate with greater fullness due to the added volume (2).

Having said that, in most cases measures of hunger/fullness do not correlate with food intake (2). This is probably because most people (86-92%) tend to eat all the food they serve for themselves. Therefore, portion control is very important if energy intake is a concern. Conversely, portion selection depends on expected fullness (6).

Nutrient composition

Macronutrients

Protein is regarded as the macronutrient that elicits greater satiety, followed by carbohydrate, followed by fat (2, 3, 4).

Alcohol, which is considered by some as a macronutrient as it contributes to energy intake, is less satiating than proteins, carbs and fat (3). Anecdotally, for many people it has the opposite effect.

Fibre

Fibre-rich foods are thought to increase satiety (1, 3). Different dietary fibres have different effects on the body. This depends on the physical and chemical properties (e.g. hydration, solubility, viscosity) of each type of fibre. Moreover, food processing can affect some of those physical properties (1).

Dietary fibre can reduce how fast and/or how much nutrients are absorbed and increase the viscosity of intestinal contents. In addition, eating high fibre foods require more chewing and, therefore, time, which allows for satiety signals to hit the brain (1).

Fermentable fibre is low in energy (1-2 kcal per gram, compared to 4 kcal per gram for carbohydrates). Therefore, fibre-rich foods represent a higher volume with lower energy (1).

One of the fibres present in oats, called β-glucan, may increase satiety at doses of 2.2 g to 5.5 g (1). Glucomannan seems to be the best at increasing satiety (3).

Other food components

Caffeine and capsaicin (the active component in chillies) can reduce appetite and energy intake (3).

Palatability

Palatability refers to how tasty a food is. There is no consensus when it comes to palatability and food intake. Some researchers postulate that highly palatable foods do not necessarily lead to greater food intake (7), while others affirm the opposite (3, 6).

Eating behaviours

There seems to be a direct correlation between the time food is in our mouth (i.e. due to chewing) and satiation (6). Eating slower can be done consciously (e.g. by counting how many times we chew) or by adding ingredients that require more chewing (e.g. raw vegetables).

Eating while distracted can make us feel less satisfied by the meal and increase the amount of food at the next meal (3, 6, 7). Some studies have found this to be true only for obese individuals under stress, while evidence seems to be less strong for people in the healthy weight range (8).

Memory

Memory plays an important role in satiety, as remembering a recent meal can decrease the amount that is eaten at the next meal (3, 6, 7). This is bad news people who suffer from some sort of memory deficiency, and at the same time presents an opportunity to set reminders to prevent excess food consumption.

References

1. Rebello CJ, O’Neil CE, Greenway FL. Dietary fiber and satiety: the effects of oats on satiety. Nutr Rev. 2016 Feb;74(2):131–47.
2. Stribiţcaia E, Evans CEL, Gibbons C, Blundell J, Sarkar A. Food texture influences on satiety: systematic review and meta-analysis. Sci Rep. 2020 Jul;10(1):12929.
3. Tremblay A, Bellisle F. Nutrients, satiety, and control of energy intake. Appl Physiol Nutr Metab = Physiol Appl Nutr Metab. 2015 Oct;40(10):971–9.
4. Njike VY, Smith TM, Shuval O, Shuval K, Edshteyn I, Kalantari V, et al. Snack Food, Satiety, and Weight. Adv Nutr. 2016 Sep;7(5):866–78.
5. Woods SC. Gastrointestinal satiety signals I. An overview of gastrointestinal signals that influence food intake. Am J Physiol Gastrointest Liver Physiol. 2004 Jan;286(1):G7-13.
6. Forde CG, Almiron-Roig E, Brunstrom JM. Expected Satiety: Application to Weight Management and Understanding Energy Selection in Humans. Curr Obes Rep. 2015 Mar;4(1):131–40.
7. Brunstrom JM. Mind over platter: pre-meal planning and the control of meal size in humans. Int J Obes (Lond). 2014 Jul;38 Suppl 1(Suppl 1):S9-12.
8. Ding L, Hamid N, Shepherd D, Kantono K. How is Satiety Affected When Consuming Food While Working on A Computer? Nutrients. 2019 Jul;11(7).

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