Prevention and management of obesity in a lifetime perspective.

The prevalence of obesity is increasing across all geographies. Obesity develops due to a disruption of the energy balance regulation. However, the cause is not well understood. Identification of causal factors that may be modified is crucial to reduce the prevalence of obesity. However, the interventions needed will likely differ between life stages. Hence, obesity research should span from pre-conception to adulthood. In this review, we point to gaps and limitations in existing research, highlight recently initiated studies from which we are awaiting results and point to future directions.

Weight loss relapse associated with exposure to perfluorinated alkylate substances.

OBJECTIVE: The purpose of this study was to test the hypothesis that perfluorinated alkylate substance (PFAS) exposures are associated with body weight increases in a dietary intervention study. METHODS: In the DioGenes trial, adults with obesity first lost at least 8% of their body weight and then completed at least 26 weeks on a specific diet. Concentrations of five major PFASs were assessed in plasma samples from study baseline. RESULTS: In 381 participants with complete data, plasma concentrations averaged 2.9 ng/mL and 1.0 ng/mL for perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS), respectively. A doubling in plasma PFOA was associated with an increase in weight at 26 weeks by 1.50 kg (95% CI: 0.88-2.11), with an increase of 0.91 kg (95% CI: 0.54-1.27) for PFHxS, independent of diet groups and sex. Associations for other PFASs were in the same direction and significant, although not after adjustment for PFOA and PFHxS. Weight changes associated with elevated PFAS exposures were similar to or larger than average changes ascribed to the different diet groups. CONCLUSIONS: Elevated plasma concentrations of PFOA and PFHxS were associated with increased weight gain that exceeded those related to the diets. Obesogenic PFASs may cause weight gain and thus contribute to the obesity pandemic.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss.

BACKGROUND: Consumption of unprocessed red meat in randomized trials has no adverse effects on cardiovascular risk factors and body weight, but its physiological effects during weight loss maintenance are not known. OBJECTIVES: We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss, and secondarily on body composition (DXA), resting energy expenditure (REE; indirect calorimetry), and cardiometabolic risk factors. METHODS: In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28-40 kg/m2 (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35). RESULTS: In per protocol analysis (n = 69), mean body weight (-1.2 kg; 95% CI: -2.1, -0.3 kg), mean fat mass (-2.7 kg; 95% CI: -3.4, -2.0 kg), and mean body fat content (-2.6%; 95% CI: -3.1, -2.1%) decreased during the maintenance phase, whereas mean lean mass (1.5 kg; 95% CI: 1.0, 2.0 kg) and mean REE (51 kcal/d; 95% CI: 15, 86 kcal/d) increased, with no differences between groups (all P > 0.05). Results were similar in intention-to-treat analysis with multiple imputation for dropouts (20 from B150 compared with 19 from B25, P = 0.929). Changes in cardiometabolic risk factors were not different between groups, the general pattern being a decrease during weight loss and a return to baseline during weight maintenance (and despite the additional mild reduction in weight and fat mass). CONCLUSIONS: Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

Prevotella abundance and salivary amylase gene copy number predict fat loss in response to wholegrain diets.

Background: Salivary amylase (AMY1) gene copy number (CN) and Prevotella abundance in the gut are involved in carbohydrate digestion in the upper and lower gastrointestinal tract, respectively; and have been suggested as prognostic biomarkers for weight loss among overweight individuals consuming diets rich in fiber and wholegrains. Objective: We hypothesized that Prevotella abundance would be linked to greater loss of body fat after wholegrain consumption among individuals with low AMY1 CN, but not in those with high AMY1 CN. Methods: We reanalyzed data from two independent randomized ad libitum wholegrain interventions (fiber intake ∼33 g/d for 6-8 weeks), to investigate the relationship between baseline Prevotella abundance and body fat loss among healthy, overweight participants stratified into two groups by median AMY1 CN. Individuals with no detected Prevotella spp. were excluded from the main analysis. Results: In both studies, individuals with low AMY1 CN exhibited a positive correlation between baseline Prevotella abundance and fat loss after consuming the wholegrain diet (r > 0.5, P < 0.05), but no correlation among participants with high AMY1 CN (P ≥ 0.6). Following consumption of the refined wheat control diets, there were no associations between baseline Prevotella abundance and changes in body fat in any of the AMY1 groups. Conclusion: These results suggest that Prevotella abundance together with AMY1 CN can help predict fat loss in response to ad libitum wholegrain diets, highlighting the potential of these biomarkers in personalized obesity management.

A double-blinded, randomized, parallel intervention to evaluate biomarker-based nutrition plans for weight loss: The PREVENTOMICS study.

BACKGROUND & AIMS: Growing evidence suggests that biomarker-guided dietary interventions can optimize response to treatment. In this study, we evaluated the efficacy of the PREVENTOMCIS platform-which uses metabolomic and genetic information to classify individuals into different 'metabolic clusters' and create personalized dietary plans-for improving health outcomes in subjects with overweight or obesity. METHODS: A 10-week parallel, double-blinded, randomized intervention was conducted in 100 adults (82 completers) aged 18-65 years, with body mass index ≥27 but <40 kg/m2, who were allocated into either a personalized diet group (n = 49) or a control diet group (n = 51). About 60% of all food was provided free-of-charge. No specific instruction to restrict energy intake was given. The primary outcome was change in fat mass from baseline, evaluated by dual energy X-ray absorptiometry. Other endpoints included body weight, waist circumference, lipid profile, glucose homeostasis markers, inflammatory markers, blood pressure, physical activity, stress and eating behavior. RESULTS: There were significant main effects of time (P < 0.01), but no group main effects, or time-by-group interactions, for the change in fat mass (personalized: -2.1 [95% CI -2.9, -1.4] kg; control: -2.0 [95% CI -2.7, -1.3] kg) and body weight (personalized: -3.1 [95% CI -4.1, -2.1] kg; control: -3.3 [95% CI -4.2, -2.4] kg). The difference between groups in fat mass change was -0.1 kg (95% CI -1.2, 0.9 kg, P = 0.77). Both diets resulted in significant improvements in insulin resistance and lipid profile, but there were no significant differences between groups. CONCLUSION: Personalized dietary plans did not result in greater benefits over a generic, but generally healthy diet, in this 10-week clinical trial. Further studies are required to establish the soundness of different precision nutrition approaches, and translate this science into clinically relevant dietary advice to reduce the burden of obesity and its comorbidities. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov registry (NCT04590989).

Effects of sleep manipulation on markers of insulin sensitivity: A systematic review and meta-analysis of randomized controlled trials.

Poor sleep habits are associated with increased risk of developing type 2 diabetes. In this review and meta-analysis, we aimed to investigate the effects of sleep manipulation on markers of insulin sensitivity from randomized, controlled trials. Sleep manipulation was defined as reduction in sleep duration, sleep quality, and circadian misalignment. A systematic literature search was conducted in three databases and resulted in 35 eligible articles. The studies included interventions on sleep restriction (26 studies), slow wave sleep suppression and rapid eye movement sleep disturbance (2 studies), sleep fragmentation (2 studies), and circadian misalignment (5 studies). The meta-analysis included 21 sleep restriction studies. Sleep restriction reduced insulin sensitivity assessed by oral or intravenous glucose tolerance test and homeostatic model assessment of insulin resistance. Whole-body insulin sensitivity was also reduced after short sleep when measured by the hyperinsulinemic euglycemic clamp, but peripheral insulin sensitivity was not affected. In addition, circadian misalignment and slow wave sleep suppression negatively affected insulin sensitivity, while rapid eye movement sleep disturbance and sleep fragmentation had no effect. In summary, the studies indicated that duration, quality, and timing of sleep are essential for metabolic function and risk of type 2 diabetes.

A protein-supplemented very-low-calorie diet does not mitigate reductions in lean mass and resting metabolic rate in subjects with overweight or obesity: A randomized controlled trial.

BACKGROUND & AIMS: The European Food Safety Authority recently recommended an increase in the protein content of total diet replacement (TDR) products from 50 to 75 g/day. The rationale was to minimize reductions in lean mass (LM) and resting metabolic rate (RMR) that occur with weight loss, and thereby facilitate maintenance of lost weight. We sought to directly compare the efficacy of TDR regimens with the new vs the current protein requirement. METHODS: We randomized 108 adults with overweight or obesity (body mass index 28-40 kg/m2) to very-low-calorie diets (VLCD) with either 52 or 77 g/day protein for 8 weeks (total energy intake of 600 or 700 kcal/day, respectively). LM was determined by dual energy X-ray absorptiometry and RMR by indirect calorimetry. RESULTS: Attrition rate was 22% in both groups. Both VLCDs decreased body weight, fat mass, LM, and RMR (all P < 0.05). Significant time-by-group interactions were detected for weight and fat mass (both P < 0.05), with corresponding reductions being smaller in the higher-protein than the standard-protein VLCD, likely because of the added calories. On the other hand, reductions in LM (6% from baseline) and RMR (9-10% from baseline) did not differ between groups (P = 0.155 and P = 0.389, respectively), and the contribution of LM to total weight loss was identical (27 ± 2% of lost weight, P = 0.973). CONCLUSIONS: Our results indicate that the proposed increase in the protein content of TDR products does not attenuate reductions in LM and RMR in individuals with overweight and obesity who are treated with <800 kcal/day VLCDs for 2 months. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov # NCT04156165.

Sex, Food, and the Gut Microbiota: Disparate Response to Caloric Restriction Diet with Fiber Supplementation in Women and Men.

SCOPE: Dietary-based strategies are regularly explored in controlled clinical trials to provide cost-effective therapies to tackle obesity and its comorbidities. The article presents a complementary analysis based on a multivariate multi-omics approach of a caloric restriction intervention (CRD) with fiber supplementation to unveil synergic effects on body weight control, lipid metabolism, and gut microbiota. METHODS AND RESULTS: The study explores fecal bile acids (BAs) and short-chain fatty acids (SCFAs), plasma BAs, and fecal shotgun metagenomics on 80 overweight participants of a 12-week caloric restriction clinical trial (-500 kcal day-1 ) randomly allocated into fiber (10 g day-1 inulin + 10 g day-1 resistant maltodextrin) or placebo (maltodextrin) supplementation groups. The multi-omic data integration analysis uncovered the benefits of the fiber supplementation and/or the CRD (e.g., increase of Parabacteroides distasonis and fecal propionate), showing sex-specific effects on either adiposity and fasting insulin; effects thought to be linked to changes of specific gut microbiota species, functional genes, and bacterially produced metabolites like SCFAs and secondary BAs. CONCLUSIONS: This study identifies diet-microbe-host interactions helping to design personalised interventions. It also suggests that sex perspective should be considered routinely in future studies on dietary interventions efficacy. All in all, the study uncovers that the dietary intervention is more beneficial for women than men.

Diets, nutrients, genes and the microbiome: recent advances in personalised nutrition.

As individuals seek increasingly individualised nutrition and lifestyle guidance, numerous apps and nutrition programmes have emerged. However, complex individual variations in dietary behaviours, genotypes, gene expression and composition of the microbiome are increasingly recognised. Advances in digital tools and artificial intelligence can help individuals more easily track nutrient intakes and identify nutritional gaps. However, the influence of these nutrients on health outcomes can vary widely among individuals depending upon life stage, genetics and microbial composition. For example, folate may elicit favourable epigenetic effects on brain development during a critical developmental time window of pregnancy. Genes affecting vitamin B12 metabolism may lead to cardiometabolic traits that play an essential role in the context of obesity. Finally, an individual's gut microbial composition can determine their response to dietary fibre interventions during weight loss. These recent advances in understanding can lead to a more complete and integrated approach to promoting optimal health through personalised nutrition, in clinical practice settings and for individuals in their daily lives. The purpose of this review is to summarise presentations made during the DSM Science and Technology Award Symposium at the 13th European Nutrition Conference, which focused on personalised nutrition and novel technologies for health in the modern world.

Physical Activity, Sedentary Behavior, and Sleep Before and After Bariatric Surgery and Associations with Weight Loss Outcome.

PURPOSE: Physical activity, sedentary behavior, and sleep have been linked to the likelihood of maintaining healthy body weight. This study aimed to determine objectively measured movement behaviors before and up to 18 months after bariatric surgery and to investigate whether preoperative levels of these movement behaviors and potential changes of these behaviors were associated with changes in body weight and boy composition. MATERIALS AND METHODS: Accelerometer determined total physical activity, moderate-to-vigorous physical activity (MVPA), light physical activity, sedentary behavior, and sleep (for six consecutive days and seven nights) were assessed approximately 3 months and 1-2 weeks before surgery as well as 6 and 18 months after surgery (n = 41). Body weight and body composition (waist circumference, fat mass, and fat-free mass) were determined at each visit. RESULTS: Mean weight loss 18 months after surgery was 42.0 ± 1.9 kg. There were no pre- to postoperative improvements in physical activity, sedentary behavior, or sleep. However, greater increases in levels of total physical activity and time spent in MVPA from 3 months before to 6 months after surgery predicted better weight loss and larger reductions in fat mass and waist circumference. Unexpectedly, a lower level of physical activity and a higher level of sedentary behavior before surgery predicted better weight loss outcomes. CONCLUSION: Objectively measured movement behaviors do not improve after bariatric surgery despite a substantial weight loss. However, increasing total physical activity and/or more time spent in MVPA after surgery may increase weight loss and lead to favorable changes in body composition.

Microbial enterotypes beyond genus level: Bacteroides species as a predictive biomarker for weight change upon controlled intervention with arabinoxylan oligosaccharides in overweight subjects.

Recent studies indicate that microbial enterotypes may influence the beneficial effects of wholegrain enriched diets including bodyweight regulation. In a 4-week intervention trial, overweight subjects were randomized to consume either arabinoxylan-oligosaccharides (AXOS) (10.4 g/d) from wheat bran or polyunsaturated fatty acids (PUFA) (3.6 g/d). In the present study, we have stratified the subjects participating in the intervention (n = 29) according to the baseline Prevotella-to-Bacteroides (P/B) ratios through a post-hoc analysis and applied a linear mixed model analysis to identify the influence of this P/B ratio on the differences in weight changes in the intervention arms. Following AXOS consumption (n = 15), the high P/B group showed no bodyweight changes [-0.14 kg (95% CI: -0.67; 0.38, p = .59)], while the low P/B group gained 0.65 kg (95% CI: 0.16; 1.14, p = .009). Consequently, a difference of -0.79 kg was found between P/B groups (95% CI: -1.51; -0.08, p = .030). No differences were found between P/B groups following PUFA consumption (0.61 kg, 95% CI: -0.13; 1.35, p = .10). Among the Bacteroides species, B. cellulosilyticus relative abundance exhibited the highest positive rank correlation (Kendall's tau = 0.51, FDR p = .070) with 4-week weight change on AXOS, and such association was further supported by using supervised classification methods (Random Forest). We outlined several carbohydrate-active enzyme (CAZy) genes involved in xylan-binding and degradation to be enriched in B. cellulosilyticus genomes, as well as multiple accessory genes, suggesting a supreme AXOS-derived glycan scavenging role of such species. This post-hoc analysis, ensuring species and strain demarcation at the human gut microbiota, permitted to uncover the predictive role of Bacteroides species over P/B enterotype in weight gain during a fiber-based intervention. The results of this pilot trial pave the way for future assessments on fiber fermentation outputs from Bacteroides species affecting lipid metabolism in the host and with direct impact on adiposity, thus helping to design personalized interventions.

Diet and exercise in the prevention and treatment of type 2 diabetes mellitus.

Evidence from observational studies and randomized trials suggests that prediabetes and type 2 diabetes mellitus (T2DM) can develop in genetically susceptible individuals in parallel with weight (that is, fat) gain. Accordingly, studies show that weight loss can produce remission of T2DM in a dose-dependent manner. A weight loss of ~15 kg, achieved by calorie restriction as part of an intensive management programme, can lead to remission of T2DM in ~80% of patients with obesity and T2DM. However, long-term weight loss maintenance is challenging. Obesity and T2DM are associated with diminished glucose uptake in the brain that impairs the satiating effect of dietary carbohydrate; therefore, carbohydrate restriction might help maintain weight loss and maximize metabolic benefits. Likewise, increases in physical activity and fitness are an important contributor to T2DM remission when combined with calorie restriction and weight loss. Preliminary studies suggest that a precision dietary management approach that uses pretreatment glycaemic status to stratify patients can help optimize dietary recommendations with respect to carbohydrate, fat and dietary fibre. This approach might lead to improved weight loss maintenance and glycaemic control. Future research should focus on better understanding the individual response to dietary treatment and translating these findings into clinical practice.

Weekly variation in diet and physical activity among 4-75-year-old Danes.

OBJECTIVE: To compare dietary intake and physical activity (PA) between days of the week in a large sample of the Danish population; furthermore, to investigate the influence of gender and age as determinants for weekly variation. DESIGN: Analysis was based on cross-sectional data from the Danish National Survey of Diet and Physical Activity 2011-2013. Dietary intake and PA were assessed by 7 d of pre-coded food diaries and pedometer-determined step counts. Dietary intake and PA on weekdays (Monday-Thursday), Friday, and weekend days (Saturday and Sunday) were compared using linear mixed models. SETTING: Survey with national representation, conducted in Denmark between 2011 and 2013. PARTICIPANTS: A random sample of 4-75-year-old Danes, n 3934 and n 3530 in analysis of dietary intake and PA, respectively. RESULTS: Energy intake during Friday and weekend days was 7-20 % higher compared with weekdays, while step counts were 10 and 17 % lower on Saturday and Sunday, respectively (all P < 0·001). Energy density of liquids and solids, consumption of added sugar, alcohol, discretionary foods, beer, wine and sugar-sweetened beverages were substantially higher, and consumption of dietary fibre, vegetables, fruit and wholegrain products were lower, during Friday and weekend days compared with weekdays (all P < 0·001). The observed patterns were present across gender and age, although weekly variation was most pronounced among children and relatively modest among the elderly. CONCLUSIONS: Weekend health behaviours of Danes display less favourable eating and PA behaviour compared with weekdays, making the weekend an important target for public health interventions aiming to improve dietary intake and PA behaviour.

Pretreatment Prevotella-to-Bacteroides ratio and salivary amylase gene copy number as prognostic markers for dietary weight loss.

BACKGROUND: The inconsistent link observed between salivary amylase gene copy number (AMY1 CN) and weight management is likely modified by diet and microbiome. OBJECTIVE: Based on analysis of a previously published study, we investigated the hypothesis that interaction between diet, Prevotella-to-Bacteriodes ratio (P/B ratio), and AMY1 CN influence weight change. METHODS: Sixty-two people with increased waist circumference were randomly assigned to receive an ad libitum New Nordic Diet (NND) high in dietary fiber, whole grain, intrinsic sugars, and starch or an Average Danish (Western) Diet (ADD) for 26 weeks. All foods were provided free of charge. Before subjects were randomly assigned to receive the NND or ADD diet, blood and fecal samples were collected, from which AMY1 CN and P/B ratio, respectively, were determined. Body weight change was described by using linear mixed models, including biomarker [log10(P/B ratio) and/or AMY1 CN] diet-group interactions. RESULTS: Baseline means ± SDs of log10(P/B ratio) and AMY1 CN were -2.1 ± 1.8 and 6.6 ± 2.4, respectively. Baseline P/B ratio predicted a 0.99-kg/unit (95% CI: 0.40, 1.57; n = 54; P < 0.001) higher weight loss for those subjects on the NND compared with those on the ADD diet, whereas AMY1 CN was not found to predict weight loss differences between the NND and ADD groups [0.05 kg/CN (95% CI: -0.40, 0.51; n = 54; P = 0.83)]. However, among subjects with low AMY1 CN (<6.5 copies), baseline P/B ratio predicted a 2.12-kg/unit (95% CI: 1.37, 2.88; n = 30; P < 0.001) higher weight loss for the NND group than the ADD group. No such differences in weight loss were found among subjects in both groups with high AMY1 CN [-0.17 kg/unit (95% CI: -1.01, 0.66; n = 24; P = 0.68)]. CONCLUSIONS: The combined use of low AMY1 CN and pretreatment P/B ratio for weight loss prediction led to highly individualized weight loss results with the introduction of more fiber, whole grain, intrinsic sugars, and starch in the diet. These preliminary observations suggest that more undigested starch reaches the colon in individuals with low AMY1 CN, and that the fate of this starch depends on the gut microbiota composition. This trial was registered at clinicaltrials.gov as NCT01195610.

Pretreatment Prevotella-to-Bacteroides ratio and markers of glucose metabolism as prognostic markers for dietary weight loss maintenance.

BACKGROUND/OBJECTIVES: Pre-treatment gut microbial Prevotella-to-Bacteroides (P/B) ratio and markers of glucose metabolism (i.e., fasting glucose and insulin) have been suggested as biomarkers for optimal weight management. However, both biomarkers need further validation, and the interactions between them for optimal weight management are largely unknown. To investigate differences in weight loss maintenance between subjects with low and high P/B ratio and the potential interactions with markers of glucose metabolism and dietary fiber intake. SUBJECTS/METHODS: Following an 8-week weight loss period using meal replacement products, subjects losing ≥ 8% of their initial body weight were randomized to one of three protein supplements or maltodextrin for a 24-week weight maintenance period. Habitual diet was consumed along with the supplements expected to constitute 10-15% of total energy. For this analysis we stratified the participants into low and high strata based on median values of pre-intervention P/B ratio, pre-weight loss Homeostatic model assessment of insulin resistance (HOMA-IR) (<2.33 or > 2.33), and dietary fiber intake during the intervention (< 28.5 or > 28.5 g/10 MJ). RESULTS: Regardless of weight maintenance regimen, subjects with high P/B ratio (n = 63) regained 1.5 (95% CI 0.4, 2.7) kg body weight (P = 0.007) more than subjects with low P/B ratio (n = 63). The regain among subjects with high P/B ratio was particular evident if HOMA-IR was high and dietary fiber intake was low. Consequently, in the high P/B strata, subjects with high HOMA-IR and low fiber intake (n = 17) regained 5.3 (95% CI 3.3, 7.3) kg (P < 0.001) more body weight compared with participants with low HOMA-IR and high fiber intake (n = 16). CONCLUSIONS: Subjects with high P/B ratio were more susceptible to regain body weight compared with subjects with low P/B ratio, especially when dietary fiber intake was low and glucose metabolism was impaired. These observations underline that both the P/B ratio and markers of glucose metabolism should be considered as important biomarkers within personalized nutrition for optimal weight management.

Fasting Glucose State Determines Metabolic Response to Supplementation with Insoluble Cereal Fibre: A Secondary Analysis of the Optimal Fibre Trial (OptiFiT).

BACKGROUND: High intake of cereal fibre is associated with reduced risk for type 2 diabetes and long-term complications. Within the first long-term randomized controlled trial specifically targeting cereal fibre, the Optimal Fibre Trial (OptiFiT), intake of insoluble oat fibre was shown to significantly reduce glycaemia. Previous studies suggested that this effect might be limited to subjects with impaired fasting glucose (IFG). AIM: We stratified the OptiFiT cohort for normal and impaired fasting glucose (NFG, IFG) and conducted a secondary analysis comparing the effects of fibre supplementation between these subgroups. METHODS: 180 Caucasian participants with impaired glucose tolerance (IGT) were randomized to twice-a-day fibre or placebo supplementation for 2 years (n = 89 and 91, respectively), while assuring double-blinded intervention. Fasting blood sampling, oral glucose tolerance test and full anthropometry were assessed annually. At baseline, out of 136 subjects completing the first year of intervention, 72 (54 %) showed IFG and IGT, while 64 subjects had IGT only (labelled "NFG"). Based on these two groups, we performed a stratified per-protocol analysis of glycometabolic and secondary effects during the first year of intervention. RESULTS: The NFG group did not show significant differences between fibre and placebo group concerning anthropometric, glycometabolic, or other biochemical parameters. Within the IFG stratum, 2-h glucose, HbA1c, and gamma-glutamyl transferase levels decreased more in the fibre group, with a significant supplement x IFG interaction effect for HbA1c. Compared to NFG subjects, IFG subjects had larger benefits from fibre supplementation with respect to fasting glucose levels. Results were robust against adjustment for weight change and sex. An ITT analysis did not reveal any differences from the per-protocol analysis. CONCLUSIONS: Although stratification resulted in relatively small subgroups, we were able to pinpoint our previous findings from the entire cohort to the IFG subgroup. Cereal fibre can beneficially affect glycemic metabolism, with most pronounced or even isolated effectiveness in subjects with impaired fasting glucose.

Prevotella Abundance Predicts Weight Loss Success in Healthy, Overweight Adults Consuming a Whole-Grain Diet Ad Libitum: A Post Hoc Analysis of a 6-Wk Randomized Controlled Trial.

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 lose more 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 the WG diet than on the RW diet, 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 t rial was registered at clinicaltrials.gov as NCT02358122.