Background: The key to effective weight loss may be to match diet and gut microbes, since recent studies have found that subjects with high Prevotella abundances in their gut microbiota losemore weight on diets rich in fiber than subjects with low Prevotella abundances.

Objectives: We reanalyzed a 6-wk, parallel, randomized trial to investigate difference in body weight changes when participants, stratified by fecal microbiota composition, consumed ad libitum a whole-grain (WG) or a refined-wheat (RW) diet.

Methods: We stratified 46 (19 men, 27 women; ages 30–65 y) healthy, overweight adults by baseline Prevotella-to-Bacteroides ratios and Prevotella abundances. Subjects with no Prevotella were analyzed separately (n = 24). Compared with the RW diet (mean = 221 g/d), the WG diet (mean = 228 g/d) had a higher fiber content (33 g/d compared with 23 g/d). Linear mixed models and correlations were applied to link 6-wk changes in body weights and metabolic and microbiota markers, according to Prevotella groups and diets.

Results: The Prevotella abundances correlated inversely with weight changes (r = −0.34; P = 0.043). Consequently, subjects with high Prevotella abundances (n = 15) spontaneously lost 1.80 kg (95% CI: −3.23, −0.37 kg; P = 0.013) more
on theWG diet than on the RWdiet, whereas those with low Prevotella abundances (n = 31) were weight stable (−0.22 kg; 95% CI: −1.40, 0.96 kg; P = 0.72). Thus, the mean difference between the Prevotella groups was 2.02 kg (95% CI: −3.87, −0.17 kg; P = 0.032). Subjects with no Prevotella lost 1.59 kg (95% CI: −2.65, −0.52 kg; P = 0.004) more on the WG diet than on the RW diet. No 6-wk changes in appetite sensations, glucose metabolisms, or fecal SCFAs were associated with the Prevotella groups.

Conclusions: Healthy, overweight adults with high Prevotella abundances lost more weight than subjects with low Prevotella abundances when consuming a diet rich in WG and fiber ad libitum for 6 wk. This further supports enterotypes
as a potential biomarker in personalized nutrition for obesity management.

This trial was registered at clinicaltrials.gov as NCT02358122.