Obesity has evolved into a global health crisis. Over the past three decades, the global prevalence of obesity has exponentially increased, with adult obesity rates more than doubling, reaching epidemic proportions. According to statistics from the World Health Organization (WHO) in 2022, there are 2.5 billion overweight adults (aged 18 and above) globally, of which 890 million suffer from obesity (Noubiap et al., 2022). Obesity is closely linked to a variety of severe health complications, including cardiovascular diseases, type 2 diabetes, non-alcoholic fatty liver disease, sleep apnea, osteoarthritis, gastroesophageal reflux disease, and certain types of cancer (Li et al., 2023; Xie et al., 2024). For instance, obesity exacerbates cardiovascular conditions by increasing blood volume and cardiac workload, inducing hypertension, promoting arteriosclerosis, triggering insulin resistance and diabetes, and leading to fatty liver and metabolic syndrome (Powell-Wiley et al., 2021). Additionally, individuals with obesity often face social discrimination and prejudice, resulting in psychological health issues such as depression and anxiety, further burdening the public health system (Westbury et al., 2023).

Treatment options for obesity primarily include lifestyle modifications, pharmacological interventions, psychological therapies, and surgical procedures. Among these, surgical interventions are considered the most effective and sustainable method for weight reduction and also significantly alleviate obesity-related complications (Welbourn et al., 2019; Ming et al., 2021). Common types of weight reduction surgeries include sleeve gastrectomy, Roux-en-Y gastric bypass, single anastomosis gastric bypass, and biliopancreatic diversion with duodenal switch. These procedures achieve weight loss by altering the gastrointestinal anatomy to limit food intake and absorption. Moreover, bariatric surgery also regulates gastrointestinal hormone secretion, such as increasing glucagon-like peptide-1 (GLP-1) levels and reducing ghrelin levels, thereby suppressing appetite and enhancing satiety, which further facilitates weight loss (Luo and Tavakkoli, 2021). Recent studies have found that bariatric surgery significantly impacts the composition and diversity of the gut microbiota, a key factor in sustained postoperative weight loss (Zhang et al., 2024).

The human gut harbors trillions of bacteria, forming a crucial component of the gut microbiome ecosystem and playing a vital role in physiological functions (Sender et al., 2016; Dimidi et al., 2019). With advancements in 16S rRNA sequencing and metagenomic sequencing, extensive research has demonstrated that the gut microbiota is intricately linked with obesity, diabetes, cardiovascular diseases, neuropsychiatric disorders, irritable bowel syndrome, and cancers (Di Tommaso et al., 2021; Jacobs et al., 2023; Larsen et al., 2010; El Tekle and Garrett, 2023; Borkent et al., 2022). Notably, recent findings suggest that changes in the gut microbiota following bariatric surgery may exert long-term effects on weight management and metabolic regulation through mechanisms involving the gut-brain axis, metabolic product formation, and immune modulation, thus being critical factors in weight reduction outcomes (Tremaroli et al., 2015; Liou et al., 2013; Fouladi et al., 2019). Therefore, it is of significant importance to conduct an in-depth study on the role of gut microbiota in weight loss treatments.

Bibliometrics, a technique that applies mathematical and statistical principles for comprehensive analysis of academic literature, was initially proposed by Alan Pritchard in 1969 (Khalil and Gotway Crawford, 2015). Compared to traditional systematic review methods, bibliometrics offers multi-level and multi-faceted analytical capabilities. It allows for quantitative analysis of vast quantities of academic literature, revealing citation relationships and the impact within the field. This analysis not only aids researchers in understanding the overall research dynamics of a particular area but also identifies key research nodes and influential studies. Furthermore, bibliometrics facilitates co-occurrence analysis to uncover relationships and trends among research topics, aiding in the understanding of knowledge evolution and expansion (Ninkov et al., 2022). Additionally, visualization techniques in bibliometrics, such as scientific knowledge maps, co-word analysis graphs, and citation network diagrams, render complex academic data more comprehensible. These maps and networks not only display hotspots and trends in research topics but also assist researchers in discovering potential research directions and collaborative opportunities. For example, by analyzing high-frequency keywords and their trends within a field, researchers can predict future research hotspots and accordingly adjust their research directions and strategies (Thompson and Walker, 2015).

In recent years, an increasing number of clinicians and researchers have focused on studies related to the gut microbiota and bariatric surgery treatment. However, there is currently a lack of systematic bibliometric analysis in this field. To address this gap, this study employs bibliometric methods to systematically visualize literature published from 1981 to 2024 concerning bariatric surgery and the gut microbiota. The research aims to provide new perspectives and ideas for obesity treatment. Specific analytical objectives include: (1) revealing the global development trends of bariatric surgery and gut microbiota research from 1981 to 2024; (2) identifying the most influential countries, regions, institutions, authors, and journals within this field; and (3) elucidating the main focus points and trends in the research on bariatric surgery and gut microbiota, predicting future research hotspots, and offering references for subsequent studies.

Increasing research has demonstrated a close relationship between gut microbiota and bariatric surgery, indicating their significant role in weight reduction (Santos et al., 2021; Luijten et al., 2019; Akagbosu et al., 2022; Han et al., 2022). This study represents the first bibliometric analysis of literature related to bariatric surgery and gut microbiota using the Web of Science Core Collection (WoSCC) database. By statistically analyzing 2,542 publications from the WoSCC database, we created visual maps to examine research trends over the past 40 years and potential future research hotspots, aiming to provide a valuable reference for researchers in this field. The number of publications and their growth trends are crucial indicators of research activity within an academic field. As shown in Figure 2, the number of publications on BS and GM has generally increased over the past 40 years, which can be divided into three phases: Phase 1 (1981–1991): The number of publications was relatively low and stable. Phase 2 (1992–2014): The publication rate gradually accelerated. Phase 3 (2015–2024): The number of publications surged dramatically. This significant growth trend can be attributed to two main factors. First, the increasing global prevalence of obesity and the rising number of patients undergoing bariatric surgery have driven the demand for related research. Second, advancements in 16S rRNA gene sequencing and metagenomic sequencing technologies have provided sophisticated tools for in-depth studies of gut microbiota. Based on the growth trend in publication numbers and the analysis of the aforementioned factors, it is reasonable to infer that this field has become a focal point for researchers in weight loss treatments. The application and mechanisms of gut microbiota in weight loss treatments are rapidly becoming a future research hotspot. Further exploration in this area could offer new approaches for the prevention and treatment of obesity, thereby advancing personalized and precision medicine.

This paper systematically compiles research literature from 95 countries worldwide, revealing that countries with higher publication volumes are primarily concentrated in North America, Asia, and Europe (Figure 3A). Globally, the United States has the highest number of publications (n = 825), accounting for 32.45% of the total, significantly outpacing other countries. The United States also leads in citation counts (Table 1), reflecting its leading position and academic contributions in this research field. Analysis of the trends in publication volumes over time (Figure 3B) indicates that although China entered this research field later, its publication volume has grown significantly in recent years, gradually approaching that of the United States. China is now the second-largest contributor globally and the most prominent research force in Asia. This can be attributed to two main factors: first, the rapid increase in obesity rates in China. According to BMI classifications, 34.8% of Chinese adults are overweight, and 14.1% are obese. Given China’s large population, these percentages correspond to very high absolute numbers (Wang et al., 2021; Chen et al., 2023). Second, the rising obesity rates pose a significant challenge to the public health system, prompting increased national funding for obesity treatment and related research. However, the average citation count of Chinese publications remains relatively low. Regarding international collaboration, the United States has the closest interactions with China and collaborates with the United Kingdom and Canada (Figure 3D). International scientific cooperation is crucial for advancing specific research fields, and fostering a mutually beneficial scenario. By visualizing the involvement of different countries in this research area from various perspectives, we can highlight leading nations and potential partners, promoting broader international research collaborations and further development in this field.

In terms of institutional analysis, the top 10 organizations in publication volume come from the United States, Brazil, Sweden, Denmark, the United Kingdom, and France (Table 2). Institutions from the United States account for 50% of the top 10, reflecting the country’s strong research capabilities in this field. The publication volumes of the top five institutions are very close, with the University of São Paulo having the highest number of publications. Although the University of Copenhagen ranks fifth in total publications, it leads in both total citations and average citations per paper, likely due to its extensive research collaborations. The overlay visualization of the inter-institutional research collaboration network (Figure 4B) shows that the University of Copenhagen collaborates most frequently with other institutions. However, Sorbonne University and Leipzig University have also strengthened their collaborations with other institutions in recent years, possibly because they started contributing to this research field relatively late. Among the top 10 funding agencies, institutions from the United States again dominate, accounting for 50% (Figure 4C). Adequate financial support is crucial for ongoing progress in research, which may be one of the primary reasons the United States maintains a leading position in this field. In summary, through multidimensional visual analysis of institutions from various countries, we can identify which institutions are at the forefront of this research area and understand the collaboration relationships between them. This information helps researchers find suitable partners in this field, further promoting inter-institutional cooperation.

Table 4 summarizes the main information about the top 10 journals in terms of publication volume in the field of bariatric surgery and gut microbiota. The journal Obesity Surgery has the highest number of publications, followed by Surgery for Obesity and Related Diseases and Nutrients, which are classified as Q3 and Q2 in the Journal Citation Reports (JCR), respectively. In terms of co-citations, Obesity Surgery, Surgery for Obesity and Related Diseases, and Nutrients are also the top three journals (Figures 5A,B), indicating their high academic standing in this field. The dual-map overlay of journals (Figure 5C) shows that research published in journals categorized under molecular/biology/genetics or health/nursing/medicine is often cited in molecular/biology/immunology and medicine/clinical journals. Journal analysis plays a crucial role in bibliometrics. By combining quantitative and qualitative research methods, we assessed the academic impact and quality levels of the major journals in this field. This provides a scientific basis for researchers to select journals, helping them identify and choose high-quality journals that match their research areas.

Through co-authorship analysis and Table 5, it is evident that the most prolific author is Karine Clement from Sorbonne University. She has long been dedicated to research in nutrition and gastroenterology. Her most cited paper is “Gut Microbiota and human NAFLD: disentangling microbial signatures from metabolic disorders,” published in 2020. This study utilized various gut microbiota sequencing tools and NAFLD diagnostic methods to provide new insights into different microbiome characteristics (Aron-Wisnewsky et al., 2020). In 2019, she published “Major microbiota dysbiosis in severe obesity: fate after bariatric surgery,” which confirmed significant changes in the gut microbiota due to severe obesity, including a reduction in microbial genetic resources (MGR) and functional pathways associated with metabolic deterioration (Aron-Wisnewsky et al., 2019). Additional strategies are needed post-BS to fully restore these changes and improve the gut ecosystem and microbiome-host interactions in severely obese patients. The second most prolific author is Professor Carel W. le Roux from the Diabetes Complications Research Centre at UCD Conway Institute, University College Dublin. In 2013, he published a study on the mechanisms of weight loss after bariatric surgery, indicating that changes in the gut microbiota are a significant cause of weight loss rather than a result (Sánchez-Alcoholado et al., 2019). In 2015, he investigated the impact of post-bariatric surgery gut microbiota changes on fat regulation by transplanting the gut microbiota of bariatric surgery patients into germ-free mice. He found that the altered microbiota post-surgery promoted reduced fat deposition in recipient mice, concluding that the gut microbiota plays a direct role in weight reduction post-surgery (Morales-Marroquin et al., 2020). This paper has been cited 589 times. Although Professor Fredrik Bäckhed ranks eighth in publication volume, he has the highest average and total citation counts. He contends that targeting the gut microbiota presents substantial potential for advancing human health. The development of next-generation probiotics is identified as a promising strategy for modulating the gut microbiome and enhancing human health. This is consistent with the future research hotspots we have analyzed (Khan et al., 2023). When evaluating a researcher’s academic contributions in a specific field, it is essential not only to consider the number of published papers but also the citation counts and the quality of the journals in which they are published. These metrics indicate that the aforementioned authors have made significant contributions to the field and suggest that they are likely to achieve further advancements in the future.

Citation analysis can evaluate the actual academic impact and current research hotspots in a specific field. The paper by Zhang H. et al., published in 2009 in the Proceedings of the National Academy of Sciences of the United States of America, is the earliest and most cited article in this field. This study observed that Roux-en-Y gastric bypass surgery significantly altered fecal microbiota composition, leading to an increase in γ-Proteobacteria (96.2% of which were Enterobacteriaceae members) and a decrease in Firmicutes and methanogens. These changes likely reflect the dual impact of surgery-induced alterations in gut microbiota and subsequent changes in food intake and digestion (Zhang et al., 2009). Additionally, a study by Judith et al., published in 2019, reported the highest burst strength (Aron-Wisnewsky et al., 2019). This comprehensive study on severely obese patients found that 75% of these patients had reduced gut microbiota gene richness (MGR), closely associated with significant metabolic complications. The research suggested that reduced MGR might be a critical factor leading to severe obesity. Although bariatric surgery can improve MGR and achieve weight loss in the short term, most patients continue to exhibit low MGR levels long after surgery. Investigating whether drugs can improve MGR is a future research direction and goal. Through a comprehensive analysis of keywords, we identified the current research frontiers and hotspots in three main areas: 1. Differences and mechanisms in GM diversity and richness changes after different bariatric surgery procedures. 2. Mechanisms of GM in weight loss treatments. 3. Application of GM-based combination therapies in the weight loss field.

Studies have shown that bariatric surgery alters the gut microbiota, and different surgical procedures have varying effects on the gut microbial community. Sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and adjustable gastric banding (AGB) each result in distinct post-operative microbiota compositions and abundances, with RYGB causing the most significant changes. These changes may be related to adaptive adjustments in the gut environment or fluctuations in pH levels (Santos et al., 2021; Morales-Marroquin et al., 2020; Khan et al., 2023; Ilhan et al., 2017). Although many studies have explored the changes in gut microbiota before and after bariatric surgery, multiple post-operative factors—including dietary habits, medication use, infection status, and circadian rhythms—may influence the detection of gut microbiota. Therefore, further in-depth research is needed to analyze the changes in gut microbiota after bariatric surgery. Changes in the composition of the gut microbiota are associated with obesity and can even vary with the degree of obesity. Certain obesity-related gut microbiota have a heightened ability to extract energy from the diet, which can lead to increased energy intake (Musso et al., 2011). Research shows that continuous feeding of the B. hetaiotaomicron strain to mice can reduce the concentration of glutamate in the blood and mitigate weight gain and obesity caused by a high-fat diet (Liu et al., 2017). An increase in the ratio of Firmicutes to Bacteroidetes is associated with promoting obesity (Ley et al., 2005). In obese individuals, the composition of genera such as Akkermansia, Faecalibacterium, Oscillibacter, and Alistipes is significantly reduced, while the proportion of Lactobacillus reuteri is relatively higher (Thingholm et al., 2019). This may be related to the different metabolites produced by various gut bacterial genera through their specific metabolic pathways, which can lead to alterations in metabolic processes. Additionally, the gut microbiota can influence metabolism through inflammatory responses, immune regulation, and the gut-brain axis (Boulangé et al., 2016; Li et al., 2018; Hartstra et al., 2015; Geng et al., 2022). Given these findings, it is crucial to further investigate the relationship between bariatric surgery and the gut microbiota. In the future, microbial preparations could potentially be used to regulate the composition and function of the gut microbiota, thereby influencing metabolism and achieving weight loss goals.

This study has several strengths. It is the first to conduct a comprehensive bibliometric analysis of the research field of bariatric surgery (BS) and gut microbiota (GM) based on the Web of Science Core Collection (WoSCC), filling a research gap and providing a reference for future studies. Utilizing five tools (Microsoft Excel 2021, CiteSpace, VOSviewer, the R package “bibliometrix,” and an online bibliometric analysis platform), we thoroughly and deeply explored and presented the research data (Aria and Cuccurullo, 2017). However, this study also has some limitations. Firstly, the search was conducted solely in the WoSCC database, though the WoSCC is recognized for its high-quality and comprehensive data and is the most commonly used tool in bibliometric analyses. However, research published in other databases (such as Scopus, PubMed, Embase, etc.) may also be significant, and there is a risk of missing relevant studies from alternative databases. Secondly, some non-English studies may have been overlooked due to language restrictions. Lastly, despite our efforts to develop a detailed and comprehensive search strategy, the diversity of keywords may have led to some omissions.

In summary, this study employed various tools including Excel 2021, VOSviewer 1.6.19, CiteSpace 6.2.R3, the “bibliometrix” package in R 4.3.0, and online bibliometric analysis platforms to conduct a bibliometric and visualization analysis of the fields of BS and GM. Over the past 40 years, research interest in this area has consistently increased. Understanding the role of gut microbiota in metabolism continues to evolve, with an increasing number of studies focusing on the changes in gut microbiota following bariatric surgery and their important roles and mechanisms in weight loss treatment. This study comprehensively analyzed global research advancements in BS and GM, and predicted future research hotspots, including specific changes in GM post-BS and their biological mechanisms, the role of GM in weight loss treatments, Research and application of gut microbiota-based microbiome products in combination with weight loss treatment is a hot topic for future studies. In recent years, the global obesity rate has been rising exponentially, leading to an increasing number of individuals requiring weight loss treatment. Future studies on bariatric surgery (BS) and gut microbiota may aim to achieve non-invasive weight loss solutions, thereby reducing patients’ surgical pain. This article aims to advance this field towards more precise and personalized treatment approaches, providing scientific evidence and new therapeutic methods for the treatment of obesity and its related metabolic diseases.