This 2013 review explores the relationship between gut microbiota composition and obesity. It highlights that obese individuals often exhibit a higher Firmicutes-to-Bacteroidetes ratio, which may enhance energy extraction from the diet. Animal studies demonstrate that transferring microbiota from obese to lean mice can induce weight gain, suggesting a causal role
This 2006 study by Ley et al. analyzed the gut microbiota of obese and lean humans, revealing that obese individuals have a higher proportion of Firmicutes and a lower proportion of Bacteroidetes. Longitudinal data showed that weight loss through caloric restriction led to an increase in Bacteroidetes, suggesting a reversible
This 2006 study by Turnbaugh et al. revealed that the gut microbiota in obese individuals and mice has an increased capacity for energy harvest, characterized by a higher Firmicutes-to-Bacteroidetes ratio. Using metagenomic sequencing and colonization experiments in germ-free mice, the researchers demonstrated that microbiota from obese donors conferred greater fat
