Table 4 Overview of human studies that demonstrate an association between obesity and compositional dysbiosis of the intestinal microbiota determined with culture-independent methods Population Analytical methods Key ﬁndings 12 Obese individuals (on diet) 2 Normal-weight individuals Clone library sequencing (16S) 19 Obese individuals (on diet) 222 Study material Faeces (3 time points) Faeces (3 time points) Faeces (2 time points) Faeces (3 time points) Faeces (2 time points) Faeces Faeces (2 time points) Faeces (2 time points) 36 Overweight/obese adolescents (on diet and physical activity) 123 18 Obese pregnant women 36 Normal-weight pregnant women 23 Overweight/obese individuals (on diet) 14 Non-obese individuals 24 Normal-weight children (prospective study) 20 Obese individuals 9 Individuals with anorexia nervosa 20 Normal-weight individuals 39 Overweight/obese adolescents (on diet and physical activity) 25 Overweight/obese children FISH/ﬂow cytometry FISH GC qPCR FISH qPCR qPCR qPCR FISH/ﬂow cytometry Obese individuals compared with lean: ; Bacteriodetes : Firmicutes Obese individuals on diet of decreased carbohydrate intake: ; Roseburia ; Eubacterium rectale subgroup of cluster XIVa ; biﬁdobacteria : Bacteroides : Clostridium : Staphylococcus During weight-loss diet: $ Bacteriodetes ; butyrate-producing Firmicutes Intestinal microbiota during infancy preceding overweight during childhood: ; biﬁdobacteria : Staphylococcus aureus Obese individuals: ; Bacteriodetes : Lactobacillus Anorexic individuals: : Methanobrevibacter smithii Obese individuals: : C. histolyticum : E. rectale-C. coccoides Upon calorie restricted diet: ; C. histolyticum ; C. lituseburense ; E. rectale-C. coccoides : Bacteroides-Prevotella group Genes Nutr (2011) 6:209–240 References Ley et al. (2006) Duncan et al. (2007)* Collado et al. (2008b)# Duncan et al. (2008)* Kallioma¨ki et al. (2008) Armougom et al. (2009) Nadal et al. (2009) FISH/ﬂow cytometry Overweighed pregnant women: Obese adolescents on diet with a high weight-loss: Santacruz et al. (2009) : Total bacteria : B. fragilis group : C. leptum group : B. catenulatum group ; C. coccoides group ; Lactobacillus group