Interactions between the brain and gut bacteria have been extensively explored in relation to various neurological and psychiatric disorders. Anorexia nervosa (AN)is thought to be associated with microbiome dysbiosis, while the pathogenesis of anorexia nervosa (AN) is unknown. For a study, researchers wanted to determine the role of the gut microbiota in the pathophysiology of AN illness. The researchers took the stool samples before and after renourishment to healthy controls, evaluated the composition and diversity of the gut microbiome of patients with AN (bacteriome and mycobiome), and compared them to healthy controls. In addition, MS and NMR were used to examine the amounts of various neurotransmitters and short-chain fatty acids (SCFA) in feces samples. Also, the researchers evaluated the biochemical, anthropometric, and psychological characteristics of the participants. The bacterial alpha-diversity parameter analysis indicated a higher Chao 1 index in AN patients before alimentation, indicating interindividual variance. Patients with AN showed symptoms of core microbiota loss as a result. Overrepresented OTUs (operation taxonomic units) in patients with AN taxonomically belonged to Alistipes, Clostridiales, Christensenellaceae, and Ruminococcaceae. Faecalibacterium, Agathobacter, Bacteroides, Blautia, and Lachnospira were underrepresented OTUs in AN patients. In comparison to controls, patients had more interindividual variation in the gut bacteriome and metagenome content, implying altered bacteriome activities. In comparison to controls, patients had lower levels of serotonin, GABA, dopamine, butyrate, and acetate in their stool samples. According to mycobiome analyses, no significant variations in alpha diversity or fungal profile composition between patients with AN and healthy controls were shown, nor was there any association between the fungal and bacterial profiles. According to researchers ‘ findings, the gut microbiome and its metabolites have a different profile in patients with severe AN. Even though therapeutic partial renourishment improved BMI and psychometric parameters, SCFA and neurotransmitter profiles and microbial community compositions did not change significantly during the hospitalization period, which could be due to only partial weight recovery.