Impact on satiety of macronutrients
What makes a snack satisfying?
Different nutrients will have different effects on hunger and subsequent energy intake. That is why we don’t only snack when we’re hungry, but it is helpful to consider the impact that macronutrients within a snack may have on satiety if we are to enjoy a snacking experience that is less likely to show on our waistline.
Protein Power
There is strong evidence that proteins possess the highest satiating value of all the macronutrients (2, 3, 4). A review conducted in 2004 showed that higher protein intake was associated with a feeling of satiety hours after the high protein food was ingested (2). Several studies have shown that protein is more satiating than other macronutrients, possibly due to increased post-prandial thermic effects, altered gastrointestinal functions and postprandial metabolism, such as increased amino acid concentration and gluconeogenesis (5).
The Fibre Factor
Dietary fibres consist of naturally occurring plant materials that the body cannot digest. High fibre foods typically take longer to chew, and they are usually more bulky, helping to increase the volume of stomach contents. Additionally, fibre rich foods are passed more slowly through the digestive system, thereby increasing the length of time nutrients can interact with intrinsic signalling factors, which promote satiety and satiation (6).
Carbohydrate – quality counts
The concept of glycaemic index (GI) has been extensively studied and lower GI foods have been shown to have a beneficial effect of slowing down the rise in blood glucose after meals. Low GI foods are slowly digestible carbohydrates that are thought to be more satiating than high GI foods, and some studies have demonstrated a reduction in energy intakes and suppression of hunger cues after eating low GI meals (7). Many low GI foods are inherently high in fibre: beans, pulses, fruit, vegetables and oats, for example.
Fat Facts
Although gastric emptying is thought to be slower when we eat fat (4), preload studies suggest that fat has the least satiating power compared to the other macronutrients (8). Lawton (9) concluded that the most important aspect influencing the size of the meal at dinner was the nutrient content, rather than the level of hunger. When subjects were most hungry, they tended to overeat on high fat foods.
In conclusion, it appears that protein confers the highest satiating effect of all macronutrients. There is some research to indicate that protein from dairy foods has a more favourable effect on satiety.
