Gut Microbiota Diversity in Lean Athletes Is Associated with Positive Energy Balance.

INTRODUCTION In contrast to obesity, little is known about the human lean phenotype associated with gut microbiota composition. OBJECTIVE We aimed to investigate whether the bacterial composition of lean athletes with a positive energy balance differs from the equal-calorie food group. METHODS Twenty-four male participants were included in this cross-sectional study: lean athletes with a positive energy balance (LA, n 12) and control group athletes (CTRLs, n 12). Nutritional data, resting and total energy expenditure, and body composition were determined. DNA was extracted from stool samples and subjected to 16S rRNA gene analysis. RESULTS We found 7 differentially abundant bacterial taxa between the LA and CTRL groups. Of those, 5 were significantly less abundant and 2 were enriched in the LA group. The following categories significantly associated with the community structure were identified: body fat parameters, BMI, energy intake and expenditure, oxygen consumption, and respiratory exchange ratio. CONCLUSIONS Although we are far from a detailed interpretation of lean human body maintenance, the primary findings of our study suggest that gut microbial composition may be a factor influencing the regulation of weight gain in lean athletes with a positive energy balance.