Gardner, C. D. | Search bioRxiv

bioRxiv2019

Long-term dietary intervention reveals resilience of the gut microbiota despite changes in diet and weight

With the rising rates of obesity and associated metabolic disorders, there is a growing need for effective long-term weight loss strategies, coupled with an understanding of how they interface with host physiology. While diet is a critical and promising area of focus, it has been difficult to identify diets that are broadly effective in long-term weight management. To explore the interaction between specific diets and bacteria within the gut, we tracked microbiota composition over a 12-month period as part of a larger dietary intervention study of participants consuming either a low-carbohydrate or low-fat diet. While baseline microbiota composition was not predictive of weight loss, each diet resulted in substantial changes in the microbiota three months after the start of the intervention; some of these changes were diet-specific and others tracked with weight loss. After these initial shifts, the microbiota returned near its original baseline state for the remainder of the intervention, despite participants maintaining their diet and weight loss for the entire study. These results suggest a resilience to perturbation of the microbiomes starting state. When considering the established contribution of obese-associated microbiotas to weight gain in animal models, microbiota resilience may need to be overcome for long-term alterations to host physiology.

microbiology↗

bioRxiv2019

Gut microbiota plasticity is correlated with sustained weight loss on a low-carb or low-fat dietary intervention

BackgroundObesity is a complex global health challenge. Although both low-carbohydrate (low-carb) and low-fat diets can lead to weight loss, there is typically substantial variability in weight and related outcomes for both diet approaches among obese but otherwise healthy adults. Elucidating individual characteristics that might contribute to sustained weight loss is critical to developing effective dietary intervention strategies. We hypothesized that structural differences in the gut microbiota explained some portion of the weight loss variability among people randomized to either a low-carb or low-fat diet, possibly related to its effects on dietary compliance.\n\nResultsOur study included two staggered cohorts of obese adults enrolled in the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study - a randomized clinical trial of either a low-fat or low-carb diet. In the discovery cohort (n=66), 161 pre-diet fecal samples were sequenced in addition to 157 samples collected after 10-weeks of dietary intervention. In the validation cohort (n = 56), 106 pre-diet fecal samples were sequenced. Pre-diet taxonomic features, such as the Prevotella/Bacteroides ratio, correlated to weight loss in the discovery cohort were not confirmed in the validation cohort. The most robust finding in the discovery cohort indicated that gut microbiota plasticity was linked to 12-month weight loss in a diet-dependent manner; subjects with higher sustained weight loss on a low-fat diet had higher pre-diet daily plasticity, whereas those most successful on the low-carb diet had greater microbiota plasticity over 10 weeks of dietary intervention. Unfortunately, because sample frequency and timing was quite different in the validation cohort, the relationship between plasticity and weight loss could not be studied in this group.\n\nConclusionsThese findings suggest the potential importance of gut microbiota plasticity in sustained weight loss. We highlight the importance of evaluating kinetic trends and in assessing reproducibility in studies of the gut microbiota.

microbiology↗