Visual stimulation with food pictures in the regulation of hunger hormones and nutrient deposition, a potential contributor to the obesity crisis

Influence of food images with different macronutrient compositions on serum ghrelin levels: Analysis in healthy males

Objective

Serum concentrations of the orexigenic hormone ghrelin fluctuate in anticipation of food intake. Moreover, presentation of food images causes an increase in serum ghrelin levels. Thus, the visual system may have a quantifiable role in the development of hunger via the endocrine system. The influence of macronutrient visualization on ghrelin has not yet been investigated.

Methods

In four separate sessions, ghrelin concentrations, insulin, and glucose levels were compared before and after the presentation of different pictures to 14 male participants. Pictures included neutral, non‐food‐related items or isocaloric dishes whose macronutrient composition corresponded predominately to protein/fat, simple carbohydrates, or complex carbohydrates.

Results

While pre/post ghrelin concentrations numerically increased in all sessions, significant increases were only observed following neutral and protein/fat pictures. The differences were not significant between food groups and compared to neutral images. Insulin levels decreased in all groups, but no significant differences were observed between sessions. The glucose concentrations were within the euglycemic range.

Conclusion

The results did not reproduce the induction of ghrelin secretion in different food images. Therefore, it is unclear whether the visual perception of food influences ghrelin secretion or whether separation into macronutrients changes the hormone response. Further research is required to differentiate the interactions of sensory‐specific satiety.

Colonic Medium-Chain Fatty Acids Act as a Source of Energy and for Colon Maintenance but Are Not Utilized to Acylate Ghrelin

The capacity of microbiota to produce medium-chain fatty acids (MCFA) and related consequences for the gastrointestinal (GI) tract have never been reported before. We verified the impact of nutrition-related factors on fatty acid (FAs) production and found that caloric restriction decreased levels of most of MCFAs in the mouse cecum, whereas overnight fasting reduced the levels of acetate and butyrate but increased propionate and laurate. A diet high in soluble fibre boosted the production of short-chain fatty acids (SCFA) and caproate whereas a high-cellulose diet did not have an effect or decreased the levels of some of the FAs. Rectal infusion of caprylate resulted in its rapid metabolism for energy production. Repeated 10-day MCFA infusion impacted epididymal white adipose tissue (eWAT) weight and lipid accumulation. Repeated infusion of caprylate rectally tended to increase the concentration of active ghrelin in mice plasma; however, this increase was not statistically significant. In Caco-2 cells, caprylate increased the expression of Fabp2, Pdk4, Tlr3, and Gpr40 genes as well as counteracted TNFα-triggered downregulation of Pparγ, Occludin, and Zonulin mRNA expression. In conclusion, we show that colonic MCFAs can be rapidly utilized as a source of energy or stored as a lipid supply. Further, locally produced caprylate may impact metabolism and inflammatory parameters in the colon.

Eating Motives and Other Factors Predicting Emotional Overeating during COVID-19 in a Sample of Polish Adults

We hypothesised that the higher levels of emotion-related predictors (eating motive in the form of affect regulation and COVID-19-related stress) would be associated with higher emotional overeating, after accounting for the effects of demographic variables (gender and BMI) and other eating motives (visual- and attitude-related predictors: liking, pleasure, visual appeal; body- and health-related predictors: need and hunger, health, weight control). Participants (N = 868; Mage = 33.53 years, SD = 11.98) completed: the Eating Motivation Survey, the Emotional Overeating Questionnaire, a COVID-19-related stress measure and a socio-demographic survey. The final step of the regression with emotional overeating was significant; affect regulation and COVID-19-related stress were significantly related to emotional overeating (ΔF p < 0.001, Adj. ΔR2 = 0.13). During the COVID-19 pandemic, eating can, on the one hand, help to cope with the current difficult situation and the negative emotions associated with it; on the other hand, frequent use of this tendency can lead to rigid regulation of affect and use of this mechanism as the dominant mechanism. Therefore, limited social contact, related disruptions in daily activities and stress resulting from COVID-19 should generate appropriate interventions, not necessarily focusing only on emotional eating, but also on the resources of the individual. It is worth encouraging specialists to implement alternative methods of contact with their patients, e.g., online.