Obesity in the United States is a major health issue resulting in numerous diseases, significant increases in early mortality and as well as economic costs. With over 70 million adults in US who are obese and 99 million overweight, it’s important to understand how we got here.
One way to better understand this health challenge is by studying the regulation of hunger and satiety, which has a considerable impact on the development and/or progression of obesity.
A research team from the Nutrition and Metabolic Diseases of the Department of Biochemistry and Biotechnology (Universitat Rovira i Virgili--Tarragona-Spain) worked with researchers from Denmark and the United Kingdom to identify a group of metabolites in the blood that is related to a greater perception of satiety after eating.
The research is part of a wider study (SATIN - SATiety INnovation) that was carried out to assess the extent to which the regulation of satiety can contribute to controlling body weight in the medium term. The current study focuses specifically on the metabolic aspects of regulating satiety.
The research, published in Nutrients, involved 140 volunteers who were overweight or obese, obesity, between 20 and 65 years old.
Following an initial 8-week low-calorie diet period, participants achieving ≥8% of weight loss were included in the subsequent 12-week randomized double-blind parallel intervention phase for weight loss maintenance (WLM), with food products designed to reduce appetite or matching control products as placebo.
An 8 hour appetite was assessed during study visits scheduled at the first visit and after a 12-weeks (second visit) post maintenance period by a self-reported appetite evaluation, when subjects arrived at the facilities after an overnight fast.
For the appetite assessment, participants received a fixed breakfast meal that provided 478 Kcal corresponding to about 20% of the daily energy requirement for an average adult distributed as 55% of energy as carbohydrates, 30% energy as fat and 15% energy as protein.
Self-reported appetite ratings were assessed using a survey using a standard psychometric response scale that measured feelings of satiety, fullness, hunger, desire to eat, and prospective food consumption.
Blood samples were also collected in fasting conditions before starting each appetite assessment for metabolic analysis. Plasma glucose and lipid profile were measured using standard enzymatic automated methods.
The authors noted that although metabolomics has been widely used in nutritional research, this is the first time it has been used to study the perception of satiety.
The results showed that higher concentrations of glycine and linoleic acid are associated with a greater sensation of satiety, while saccharose and some sphingomyelins (C32:2, C38:1) are negatively associated.
“Glycine is present in the nervous system and acts as a neurotransmitter binding to several receptors and inhibiting many chemical processes. Its effects seem to be similar to the gamma-Aminobutyric acid (GABA) action...According to this study, participants with greater postprandial satiety responses had a significantly higher median iAUC of several plasma amino acids concentrations, including glycine.
"Higher circulating concentrations of linoleic acid were also positively associated with higher postprandial satiety. To our knowledge, there is no previous study on circulating individual fatty acids relationships with appetite. Reduced appetite ratings were observed acutely after administering emulsions enriched with linoleic acid compared with oleic and stearic acid through upper intestinal perfusions to lean human subjects,” the report noted.
Study author Mònica Bulló told us that while the exact mechanisms linking these metabolites with satiety regulation are unknown, previous studies suggest metabolites with specific pathways involved in satiety regulation like neuropeptide Y-like receptors and the endocannabinoid system may be the answer.
The findings contribute to designing possible strategies for measuring satiety more objectively than the habitual methods and may also lead to more effective strategies for controlling appetite and body weight.
By identifying the substances that make it possible to predict satiety, more personalized nutrition programs can be implemented to control hunger and satiety by adjusting the concentration of these metabolites in blood.
“This is the first study identifying a set of metabolites associated with postprandial satiety in overweight/obese [populations]. A better knowledge of specific mechanisms modulating satiety together with a specific metabolic signature identifying better responders to satiety sensations could be useful for the design of personalized strategies to fight obesity and for the design of food products with this objective,” Bulló told NutraIngredients-USA.
Bulló added that if these results are replicated in other studies, developing new products targeting satiety would be a potential application.
2021 Feb 8;13(2):549. doi: 10.3390/nu13020549
"Metabolites Associated with Postprandial Satiety in Overweight/Obese Participants: The SATIN Study"
Authors: L. Camacho-Barcia et al.