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Behaviour, Appetite and Obesity
Abbreviations: cfu, colony-forming units; LPR, Lactobacillus rhamnosus CGMCC1.3724
The increase in the prevalence of obesity observed over the last few decades has favoured the numerous investigations that have contributed to better understand the effects of a modern lifestyle on energy balance, body composition and metabolic health. Among the studied potential determinants of obesity, the intestinal microbiota has been proposed to have an impact on energy balance in both animals and humans(1,2).
Microbiota may be perceived as an 'organ' that contributes to the metabolism and plays a role in energy storage. The human gut microbiota is composed of trillions of bacteria belonging mainly to two bacterial divisions: Firmicutes and Bacteroidetes. Although the diet has an impact on the composition of the gut microbiota(3-5), these bacteria have been proposed to participate in the development of obesity and diabetes(6-8). Animal studies have shown differences in gut microbiota composition associated with obesity(9). Lean mice have a higher relative abundance of Bacteroidetes and a lower abundance of Firmicutes when compared with obese rodents(9). Inoculation of the gut microbiota of obese mice into axenic mice has been shown to induce a significant fat mass gain when compared with that of the gut microbiota of lean animals into mice(10). These data suggest, at least in mice, a potential role for gut microbiota in the development of obesity. In human subjects, Million et al.(11)have recently demonstrated an association between Lactobacillus and weight. They found that certain species of Lactobacillus are present in normal-weight individuals, while other species of Lactobacillus are present in obese individuals(11). Unlike in diabetes(12,13), changes in gut microbiota composition associated with obesity or weight loss are less clear in humans. In 2006, Ley et al.(6)showed that after consumption of a carbohydrate- or fat-restricted low-energy diet, obese subjects had an increased proportion of Bacteroidetes and a decreased abundance of Firmicutes in their gut, confirming observation made in rodents. However, other studies...