Ever notice how you tend to feel fuller from a thick fruit smoothie than from straight fruit juice? It's not your imagination; the thickness and viscosity of a beverage can greatly influence your levels of satiety, or feelings of fullness, and help suppress hunger.
Image by khawkins04
This advice comes primarily from one study published in Physiology & Behaviour. In the study, researchers compared beverages that were identical in almost all aspects, except for the viscosity of the beverage. It demonstrated that the thicker drinks seemed to be better at suppressing hunger than thinner, less viscous ones.
Still, the amount of calories that the beverage contains matters, too. Another study in the The American Journal of Clinical Nutrition found that the degree to which a beverage had helped provide satiety depended on both its thickness (as well as creaminess, in the study's case) and the actual nutrients it provided. A thick, higher calorie drink was shown to be far more satiating than a thick, lower calorie drink.
The explanation is that viscous liquids stretch the stomach in the same way solid foods do and don't leave your stomach as quickly; and textures like thickness cue expectations of high satiety. Together, these seem to suggest they could influence appetite and possibly even intake at a later meal.
So, if you choose to drink your calories, you're better off choosing or making thicker, more viscous liquids (or even homemade protein smoothies) to curb your appetite and hunger. Just make sure the smoothies are not overly sugary.
Beverage viscosity inversely related to postprandial hunger in humans [Physiology & Behaviour]
Stephanie Lee is a geeky health and fitness freelance writer. You can follow her shenanigans on Twitter or on her YouTube channel.