Background: Obesity is a global issue, the development of which depends on many interacting factors. Among these, hormones secreted in the gastrointestinal tract play an important role. The aim of this review was to assess the impact of these hormones on the functions of adipose tissue. Methods: The analysis was based on the latest research concerning both adipose tissue and gastrointestinal hormones. Results: It was found that these hormones can significantly affect adipose tissue, both directly and indirectly. Some hormones, when secreted in excess, can stimulate adipose tissue formation processes, while others can inhibit them. The impact of hormones depends on the location and type of adipose tissue as well as the physiological state of the body. It should also be noted that no hormone acts in isolation but in close cooperation with other factors. Conclusions: The relationship between gastrointestinal hormones and adipose tissue, and their role in obesity, is a complex and evolving field of study. Further research is necessary, particularly into the interactions between hormones and other factors, as well as their mutual interactions.

The enteroendocrine system of the gastrointestinal (GI) tract is the largest endocrine organ in the human body, playing a central role in the regulation of hunger, satiety, digestion, and energy homeostasis. Numerous factors—including dietary components, physical activity, and the gut microbiota—affect the secretion of GI hormones. This study aims to analyze how these factors modulate enteroendocrine function and influence systemic metabolic regulation. This review synthesizes the current scientific literature on the physiology and distribution of enteroendocrine cells and mechanisms of hormone secretion in response to macronutrients, physical activity, and microbial metabolites. Special attention is given to the interactions between gut-derived signals and central nervous system pathways involved in appetite control. Different GI hormones are secreted in specific regions of the digestive tract in response to meal composition and timing. Macronutrients, particularly during absorption, stimulate hormone release, while physical activity influences hormone concentrations, decreasing ghrelin and increasing GLP-1, PYY, and leptin levels. The gut microbiota, through fermentation and metabolite production (e.g., SCFAs and bile acids), modulates enteroendocrine activity. Species such as Akkermansia muciniphila are associated with improved gut barrier integrity and enhanced GLP-1 secretion. These combined effects contribute to appetite regulation and energy balance. Diet composition, physical activity, and gut microbiota are key modulators of gastrointestinal hormone secretion. Their interplay significantly affects appetite regulation and metabolic health. A better understanding of these relationships may support the development of personalized strategies for managing obesity and related disorders.

Glucose-dependent insulinotropic polypeptide is one of the principal incretin hormones involved in the regulation of glucose homeostasis, lipid metabolism, and adipocyte function. Increasing evidence indicates that its biological actions differ substantially between adipose tissue depots. The aim of this narrative review with a structured literature search was to summarize current evidence on the role of GIP in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), incorporating preclinical, clinical, and genetic data. Animal studies have demonstrated that VAT is characterized by higher expression of the GIP receptor (GIPR) and greater sensitivity to the lipogenic and proinflammatory effects of GIP. Activation of GIPR in VAT promotes lipid accumulation, inflammation, and insulin resistance. Conversely, pharmacological blockade or genetic deletion of GIPR confers protection against diet-induced obesity and leads to improvements in metabolic parameters. In SAT, GIP exerts more heterogeneous and metabolically context-dependent effects that differ according to insulin sensitivity and obesity status. Moreover, under specific conditions, GIP may promote lipolysis in SAT, distinguishing its actions in this depot from those observed in VAT. These observations may help explain the efficacy of dual and triple incretin receptor agonists, including tirzepatide and retatrutide, which produce significant improvements in body weight and metabolic outcomes. Collectively, current evidence supports a depot-specific and context-dependent role of GIP in adipose tissue biology and underscores the therapeutic potential of targeting the GIP/GIPR axis in obesity and metabolic disease.

Background/Objectives: Ghrelin is a key orexigenic hormone involved in the regulation of appetite and energy homeostasis, and its fasting circulating concentrations may reflect long-term energy balance and nutritional status. The aim of the study was to assess the associations between habitual daily energy and macronutrient intake from a conventional diet and the fasting total ghrelin concentrations in individuals with different nutritional status and to evaluate the postprandial ghrelin response following consumption of a standardized meal. An additional aim was to identify body composition parameters predictive of ghrelin concentrations. Methods: The prospective study included 76 individuals aged 40–60 years, classified into four body mass index (BMI) groups. Body composition was assessed using dual-energy X-ray absorptiometry (DXA). Energy and macronutrient intake was evaluated based on standardized 3-day food records. Ghrelin concentrations were measured in the fasting state and at 60, 120, 180, and 240 min after consumption of a standardized mix liquid meal (Nutridrink Protein, 459 kcal). Results: Fasting total ghrelin concentrations were not associated with recent energy or macronutrient intake. In women, changes from the baseline differed across BMI groups at 60 and 120 min, whereas no between-group differences were observed in men. In the regression analyses, BMI and gynoid region fat showed significant coefficients in women, although the overall model was not significant, while gynoid region fat was significantly associated with fasting ghrelin in men. Conclusions: Fasting total ghrelin appears to reflect longer-term metabolic phenotype and adipose tissue distribution rather than short-term variation in habitual energy or macronutrient intake. The BMI-dependent differences in the early postprandial response observed in women further suggest that nutritional status may modify dynamic ghrelin regulation in a sex-specific manner. These findings indicate that ghrelin should not be interpreted solely as an acute marker of dietary intake, but rather within the broader context of body composition, fat distribution, and sex-related metabolic regulation.