Gut Microbiota Is Linked to Physical Health Improvements Resulting from Energy-Restricted Diet and Exercise: A Randomized Controlled Trial in Healthy Adults

Animal studies have demonstrated that energy-restricted diets and exercise affect the gut microbiome and are positively linked to physical health; however, less is known about the impacts of various patterns of dietary restriction combined with exercise on the gut microbiota and associated health outcomes in humans. This study aimed to determine if an energy-restricted diet combined with resistance training altered the gut microbiome, and whether any changes were associated with differences in body composition, dietary intake, or biomarkers of metabolic health. Twenty-six healthy males and females, aged 19–36 years with BMIs of 22–35 kg/m2, were enrolled in a 2-arm parallel, randomized controlled trial and followed either a 5:2 intermittent fasting (IFT, n = 13) or continuous energy restriction (CERT, n = 13) diet combined with supervised resistance training for 12 weeks. Both treatments resulted in decreased body weight and increased lean body mass. Shifts in the abundance of, Faecalibacterium prausnitzii, a high butyrate producer, was positively associated with changes in lean body mass (IFTp = 0.05, CERTp = 0.01) in both the groups. Moreover, in the CERT group, changes in Coprococcus genus were negatively associated with energy (p = 0.009) and fat intake (p= 0.03) and positively associated with body fat (p = 0.02). Overall, the findings indicate that using resistance training paired with either intermittent or continuous energy restriction, result in similar changes in bacterial diversity and shifts in relative abundance of bacterial taxa. The shift in specific bacterial taxa were positively associated with measures of physical health providing further support to the proposed relationship between energy consumption, exercise, gut microbiota, and physical health.