Background: Normal weight obesity (NWO), defined by a normal body mass index (BMI) but increased body fat percentage (BF%), is associated with an increased risk of cardiovascular disease and mortality. NWO is characterized by inflammation and muscle wasting in chronic kidney disease (CKD), but the underlying mechanisms remain largely unknown. Gut microbiota has been implicated in the regulation of host metabolism and may play important roles in the development of NWO in CKD.

Methods: In this case-control study, we examined the gut microbial diversity and taxonomy in 96 hemodialysis patients with normal weight (BMI <25 kg/m² and BF% ≤25% for men or ≤35% for women, n = 32), NWO (BMI <25 kg/m² and BF% >25% for men or >35% for women, n = 32), and overweight/obesity (BMI ≥25 kg/m², n = 32), matched for age, gender, and diabetes. BF% was measured using bioimpedance spectroscopy device. Gut microbiota was determined by 16S rRNA sequencing.

Results: We found that α-diversity was significantly different among the 3 adiposity phenotypes, with NWO being the least diverse. α-diversity was positively correlated with BMI, subjective global assessment score, and physical activity, but negatively correlated with interleukin-6 and tumor necrosis factor-α. Patients with or without NWO were distinguished with respect to principal coordinate analysis of β-diversity. Notably, the relative abundance of butyrate-producing bacteria, such as Faecalibacterium prausnitzii and Coprococcus, was markedly reduced in patients with NWO.

Conclusion: Our findings support associations between gut dysbiosis and a proinflammatory and catabolic state in hemodialysis patients with NWO.