Fig. 3

Proposed human gut microbiota-dependent energy extraction. We propose that intestinal transit time diversifies the gut microbiome community structures into preferred community structures captured by enterotypes (B-type, Bacteroides; R-type, Ruminococcaceae; and P-type, Prevotella) with the B-type and R-type being most distinct in terms of transit time and alpha-diversity. The B and R-type enterotypes differ in alpha-diversity and colonic fermentation, which in essence is the trade-off between saccharolytic and proteolytic metabolism, which may affect the enterotypes’ overall efficiency to extract energy from food. This could potentially translate into different body weight. The stars (*) refer to findings from a previously published paper showing that enterotypes differ in metabolic capacity and growth potential [14]