Setting their study (free to access via the link below) within the context of a global obesity epidemic, Murray et al. suggest that overeating pleasurable, energy dense foods and beverages with a low appetite value could be a major contributor, and that cutting consumption of these products could help.
Compliance with weight management programs relies on judging the appetite value of food, they write – determined by its volume, whether it is liquid or solid and its energy density and palatability.
Consequently, the team say that entrapping large volumes of water or air into food could be an alternative approach to designing foods and beverages with an increased ability to satiate but with reduced caloric density.
The scientists cite two other recent studies – Melnikov et al. 2014 and Peters et al. 2014 – showing that aerated drinks significantly reduce hunger and increase satiety more than non-aerated foods.
Sweetened, dairy-based drink used in trial
In this study, Murray et al. report on a randomized crossover trial involving 18 healthy male volunteers consuming three different skimmed milk-based test products of 110kcal each.
Two drinks containing skimmed milk powder, water, xanthan gum and lemon syrup were aerated to foams by whipping to 490ml: one of which was designed to be more stable in the stomach than the other. A third non-aerated drink with the same ingredients was used as a control.
The subjects, who fasted beforehand and were told not to drink alcohol or exercise, were told to drink 150g of one of the three drinks (selected on a random basis on each test day) within 10 minutes; MRI measurements and appetite assessments were carried out for the next four hours.
During this time, stomach contents (intra-gastric foam, air and liquid) were imaged using magnetic resonance imaging (MRI) – foam was visualized for the first time using this technology, the authors believe – while self-reported appetite ratings were collected and quantified.
Foam stability enhances ‘hunger suppression’ effect?
Compared with the control, both foams caused significant increased gastric volumes and reduced hunger, with the more stomach-stable foam also showing a significantly slower decrease in total gastric content and foam volume. Both foams returned similar ‘reported hunger’ scores.
“In conclusion, this trial provides novel insights, to our knowledge, of the intra-gastric behaviour of aerated drinks,” Murray et al. write, noting their ability to measure separate volumes of foam liquid and air in the stomach.
“The data suggest that the hunger suppression induced by aerated drinks could largely be explained by effects on gastric volumes and emptying, which may be further enhanced by foam stability.
“Such knowledge and methods could be useful to aid the manufacture of aerated products by providing an objective assessment of in vivo performance and improved understanding of mechanisms affecting gastrointestinal physiology and appetite,” they add.
Title: ‘Aerated drinks increase gastric volume and reduce appetite as assessed by MRI: a randomized, balanced, crossover trial’
Authors: Murray, K., Placidi, E., Schuring, E., Hoad, C, Koppenol, W., Arnaudov, L., Blom, W., Pritchard, S., Stoyanov, S., Gowland, P., Spiller, R., Peters, H., Marciani, L.
Source: American Journal of Clinical Nutrition (AJCN), Published online ahead of print, December 3 2014, doi:10.3945/ajcn.114.096974