Beneficial Effects of a Dietary Weight Loss Intervention on Human Gut Microbiome Diversity and Metabolism Are Not Sustained during Weight Maintenance

Abstract

Objective: In the present study, we examined the effect of a very low-calorie diet(VLCD)-based obesity program on human gut microbiome diversity and metabolism during weight loss and weight maintenance.

Methods: Obese subjects underwent 3 months of VLCD followed by 3 months of weight maintenance. A lean and an obese control group were included. The microbiome was characterized by performing high-throughput dual-indexed 16S rDNA amplicon sequencing.

Results: At baseline, a significant difference in the Firmicutes/Bacteroidetes ratio between the lean and obese individuals was observed (p = 0.047). The VLCD resulted in significant alterations in gut microbiome diversity from baseline to 3 months (p = 0.0053). Acinetobacter represented an indicator species for the observed effect (indicator value = 0.998, p = 0.006). Metabolic analyses revealed alterations of the bacterial riboflavin pathway from baseline to 3 months (pnom = 0.0078). These changes in diversity and bacterial metabolism induced by VLCD diminished during the weight maintenance phase, despite sustained reductions in body weight and sustained improvements of insulin sensitivity.

Conclusion: The present data show that a VLCD is able to beneficially alter both gut microbiome diversity and metabolism in obese humans, but that these changes are not sustained during weight maintenance. This finding might suggest that the microbiome should be targeted during obesity programs.

Fig. 1

CAP of the dietary intervention group explaining variance in the microbiota. Baseline (0 months) = 0, VLCD dietary intervention (3 months) = 3, weight maintenance period (6 months) = 6.

Fig. 2

Unconstrained PCoA of the intervention group and both control groups. A: at the beginning of the study period (0 months). B: at the end of the study period (6 months).

Fig. 3

Abundance of indicator genus Acinetobacter over time in the VLCD group. Increase of Acinetobacter due to VLCD intervention is statistically significant. Baseline (0 months) = 0, VLCD dietary intervention (3 months) = 3, weight maintenance period (6 months) = 6.

Fig. 4

Relative abundance of the riboflavin pathway during the dietary intervention. Nominal significant differences between time points. Baseline (0 months) = 0, VLCD dietary intervention (3 months) = 3, weight maintenance period (6 months) = 6.