|Infusions of nutrient solutions via a tube is often the last resort for doctors to save anorexic patients' lives - it's yet nothing anyone should do voluntarily for the satiety plus Spetter et al. observed.|
As the Dutch researchers point out, the interaction between oral and gastric signals is an important part of food intake regulation.
In that, Spetter et al. are not the first to obversve that bypassing the oral taste receptors may diminish the suppression of hunger and increases gastric emptying rate. The role of appetite hormones, like cholecystokinin-8 and ghrelin, in this process, however, is still unclear.
The objective of Spetter et al.'s latest study was thus to determine the contributions of gastric and oral stimulation to subsequent appetite and hormone responses and their effect on ad libitum intake.
The scientists recruited fourteen healthy male subjects (age 24.6 ± 3.8y, BMI 22.3 ± 1.6 kg/m²) who participated in their randomized, single-blinded, cross-over experiment with 3 treatmentsessions:
- Stomach distention, only: naso-gastric infusion of 500 mL/0 kJ water,
- Stomach distention with caloric content: naso-gastric infusion of 500 mL/1770 kJ chocolate milk, and
- Stomach distention with caloric content and oral exposure: oral administration of 500 mL/1770 kJ chocolate milk.
|Hunger & desire to eat increase significantly faster after isocaloric liquid vs. solid meals (Tieken. 2007)|
Take a look at the data from Tieken et al. (2007) on the left, for example. They found that a liquid meal providing 25% of the daily energy requirement provides a lower and less sustained suppression of hunger and desire to eat than an isocaloric solid meal.
|Figure 1: Fullness rating (top) and desire do eat (bottom) in response to infusion (light and dark grey bars) of water and chocolate milk, respectively vs. the ingestion of chocolate milk (dark bars; Spetter. 2014).|
Things never are as you would expect them to be
Now, everyone would expect that the decrease in desire to eat and the increased fullness in response to the regular (=oral) ingestion of chocolate milk would significantly reduce the energy intake on a subsequent meal, right?
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