Imbalance in gut bacteria may play a critical role in the development of obesity

Imbalance in gut bacteria may play a critical role in the development of obesity
| Image credit: © Protsenko Dmitriy – © Protsenko Dmitriy –

According to new research, the composition and volume of gut bacteria in young children at age 3.5 years can predict overweight based on body mass index (BMI) at age 5, regardless of whether they were born prematurely.1

The analysis, presented at the 2023 European Congress on Obesity (ECO), identified differences in gut-colonizing bacteria seen in adults with obesity, indicating that changes in the gut microbiota predispose to obesity in later life. begin in early childhood.

“The gut microbiota is emerging as an important factor in early life capable of influencing weight gain in childhood and later life,” Gaël Toubon of Inserm at Université Paris Cité and Université Sorbonne Paris said in a statement. Nord.1 “Our findings reveal how an imbalance in different bacterial groups may play an important role in the development of obesity.”

As the composition of the gut microbiota evolves and changes in the first months and years of life, disruption of its development is associated with conditions later in life, such as inflammatory bowel disease, diabetes, and childhood obesity.2 However, the associations between the gut microbiota and changes in BMI during infancy and pediatric overweight remain unclear, and data on preterm infants remain limited.

To better understand these associations, Toubon and colleagues investigated how the gut microbiota of 3.5-year-old children from 2 national birth cohorts in France was associated with their BMI at 5 years and changes in their BMI between the 2 and the 5 years. Adjustment was made for confounding factors, including child’s age and sex, gestational age, mode of delivery, breastfeeding status, preconception maternal BMI, and country of birth.

A total of 143 preterm infants (born ≤32 weeks gestational age) from the national EPIPAGE2 study conducted in all maternity and neonatal units in France in 2011 and a total of 369 term infants (born ≥33 weeks gestational age) were included. gestational age). ) from the national ELFE follow-up study of 18,000 children born in metropolitan France in 2011. The researchers collected stool samples from infants at 3.5 years of age.

Upon analysis, the genetic profile of the microbiota suggested a positive association between the 5-year BMI z-score and the proportion of gut bacteria. firmicutes to Bacteroidetes that are directly related to obesity. Further Bacteroidetesin comparison with firmicutes, were associated with greater thinness in individuals. The researchers noted that these gut bacteria affect weight by regulating the amount of fat an individual can absorb.

“Children with a higher ratio of Firmicutes to Bacteroidetes will absorb more calories and are more likely to gain weight,” Toubon said.1

Furthermore, the analysis found that 6 types of gut bacteria were highly predictive of BMI z-score at 5 years. The data showed a higher abundance of 3 categories of bacteria (Eubacterium hallii group, Fusicatenibacter and Eubacterium ventriosum group) were identified as a risk factor for a higher BMI z-score. Meanwhile, a greater number of 3 types of bacteria (Eggerthella, Colidextribacter and Ruminococcaceae CAG-352) were associated with a lower BMI z-score.

The research team found that some types of bacteria were associated with changes in BMI z-scores between ages 2 and 5, suggesting that some were involved in a faster rate of progression in BMI z-scores between ages 2 and 5. and 5 years and others were more protective against more rapid progression.

The analysis also showed that both the predicted biosynthesis of steroid hormones and biotin gut microbiota metabolic pathways were associated with lower BMI z-score at 5 years. Being born prematurely made no difference to later BMI, according to the researchers. Toubon noted that the gut microbiota is not only affected by the bacteria involved, but also by what they do.

“Further research is needed to delve into the specific bacterial species that influence risk and protection and to better understand when the shift to an obesity-friendly gut microbiota may take place, and thus the timing of possible interventions,” Toubon said.1


  1. Easoobesity. A young child’s gut bacteria predict whether they will be overweight at age 5. Eurek alert! May 19, 2023. Accessed May 23, 2023.
  2. Geng J, Ni Q, Sun W, Li L, Feng X. Links between gut microbiota and obesity and obesity-related diseases. biomedical pharmacist. 2022;147:112678. doi:10.1016/j.biopha.2022.112678

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