The baseline gut microbiota directs dieting-induced weight loss trajectories.

Abstract Background and aims Elucidating key factors affecting personal responses to food is the first step towards implementing personalized nutrition strategies in e.g. weight loss programs. We here aimed to identify factors of importance for individual weight loss trajectories in a natural setting where subjects were provided dietary advice but otherwise asked to self-manage the daily caloric intake and data reporting. Methods A 6-months weight-reduction program with longitudinal collection of dietary, physical activity, body weight, and fecal microbiome data as well as SNP genotypes in 83 subjects was conducted followed by integration of the high-dimensional data to define the most determining factors for weight loss in a dietician-guided, smartphone-assisted dieting program. Results The baseline gut microbiota was found to outperform other factors as a pre-dieting predictor of individual weight loss trajectories. Weight loss was also linked to the magnitude of changes in abundances of certain bacterial species during dieting. Ruminococcus gnavus (MGS0160) was significantly enriched in obese individuals, and decreased during weight loss. Akkermansia muciniphila (MGS0120) and Alistipes obesi (MGS0342) were significantly enriched in lean individuals, and their abundance increased during dieting. Finally, Blautia wexlerae (MGS0575) and Bacteroides dorei (MGS0187) were the strongest predictors for weight loss when present in high abundance at baseline. Conclusion Altogether, the baseline gut microbiota was found to excel as a central personal factor in capturing the relationship between dietary factors and weight loss among individuals on a dieting program.