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Regaining body weight after weight reduction further increases pulse wave velocity in obese men with metabolic syndrome.
Liang, KW, Lee, WJ, Lee, IT, Lin, SY, Wang, JS, Lee, WL, Sheu, WH
Medicine. 2018;97(40):e12730
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Atherosclerosis can increase stiffness of the aorta and, therefore, increased pulse wave velocity (PWV), which is a predictor for cardiovascular disease and mortality. Metabolic syndrome (MetS), diabetes and obesity increase the risk of aortic stiffness and higher PWV. Weight loss may reduce arterial stiffness but mechanisms are not known. The aim this study was to investigate changes over time of PWV, ankle-brachial index (ABI, a marker for arterial disease of the leg), insulin resistance and inflammatory markers after weight loss and regained weight in obese non-diabetic men with MetS compared to lean controls. Obese participants followed a three months weight loss programme based on diet and exercise during which they lost an average of 8.6kg and saw statistically significant improvements in blood pressure and many biochemical markers but not in PWV or ABI. At the second follow-up visit, at 60 months, they had regained their weight, blood pressure and most biochemical markers were back to baseline whilst PWV and adiponectin were worse than before weight loss. Increases in blood pressure but not weight, hs-CRP (an inflammatory marker) or insulin resistance correlated with the increase in PWV after weight regain. Although healthy controls also gained weight over the 60 months study duration, their increase in PWV was significantly lower than in obese participants. Their PWV was also lower at baseline.
Abstract
Subjects with metabolic syndrome (MetS) or obesity have worse arterial stiffness. However, there have been no studies addressing time-sequential changes in pulse wave velocity (PWV) after weight loss and then regaining weight in obese non-diabetic men with MetS.We prospectively enrolled 40 obese, non-diabetic men with MetS undergoing a 3-month weight reduction program. Another 26 lean and healthy men were recruited for comparisons. Oral glucose tolerance test and brachial ankle (ba) PWV were assessed in study subjects. Eighteen obese non-diabetic MetS and 15 lean control subjects had follow-ups at the 60th month.The body weight of obese MetS decreased from 94.8 ± 7.6 to 86.1 ± 9.0 (N = 18, P < .001) after a 3-month weight reduction program but regained gradually thereafter to 93.6 ± 11.6 kg at the 60th month (P < .001 versus 3rd month). baPWV decreased after weight loss slightly (P = .240) while weight regain significantly increased the baPWV (from 3rd month, 1358 ± 168 to 60th month 1539 ± 264 cm/sec, P < .001). Systolic and diastolic blood pressure increments correlated with the increment of baPWV after weight regain. At the 60th month, lean controls (N = 15) had increases in body weight while their baPWV increased non-significantly. The increments of baPWV after weight regain in obese MetS were significantly higher than the increment of baPWV in lean controls after weight gain.In conclusion, regaining body weight after weight reduction worsened arterial stiffness with significant increase of baPWV in obese non-diabetic MetS.
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The effects of short-term fasting on quality of life and tolerance to chemotherapy in patients with breast and ovarian cancer: a randomized cross-over pilot study.
Bauersfeld, SP, Kessler, CS, Wischnewsky, M, Jaensch, A, Steckhan, N, Stange, R, Kunz, B, Brückner, B, Sehouli, J, Michalsen, A
BMC cancer. 2018;18(1):476
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Short-term fasting (STF) has been shown to protect healthy cells against the adverse effects of chemotherapy while making tumor cells more vulnerable to it. The present randomised pilot cross-over study was designed to assess the effect of a 60 hour STF on quality of life (QOL), well-being and fatigue in patients with gynaecological cancer undergoing chemotherapy. Group A was randomised to a STF during the first three of six scheduled chemotherapies (36 h before to 24 h after the chemotherapy) followed by non-calorie restricted nutrition during the following three chemotherapies. During the fasting period subjects received unrestricted amounts of water, herbal tea, 2x100cl vegetable juice and small standardized quantities of light vegetable broth with a maximum total daily energy intake of 350 kcal. Group B was allocated to a vice versa sequence of nutrition. All measurements were performed at baseline and eight days after each chemotherapy cycle. A variety of questionnaires were used for assessment of QOL, general well-being and fatigue. 34 patients with breast or ovarian cancer completed the study. Fasting was safe and all reported side effects were of low grade. STF led to a better tolerance to chemotherapy with less compromised QOL and reduced fatigue within the 8 days after chemotherapy. At the final consultation the majority of patients reported better tolerance to chemotherapy with STF. The authors conclude that STF during chemotherapy is feasible and has beneficial effects on QOL, well-being and fatigue.
Abstract
BACKGROUND This pilot trial aimed to study the feasibility and effects on quality of life (QOL) and well-being of short-term fasting (STF) during chemotherapy in patients with gynecological cancer. METHODS In an individually-randomized cross-over trial patients with gynecological cancer, 4 to 6 planned chemotherapy cycles were included. Thirty-four patients were randomized to STF in the first half of chemotherapies followed by normocaloric diet (group A;n = 18) or vice versa (group B;n = 16). Fasting started 36 h before and ended 24 h after chemotherapy (60 h-fasting period). QOL was assessed by the FACIT-measurement system. RESULTS The chemotherapy-induced reduction of QOL was less than the Minimally Important Difference (MID; FACT-G = 5) with STF but greater than the MID for non-fasted periods. The mean chemotherapy-induced deterioration of total FACIT-F was 10.4 ± 5.3 for fasted and 27.0 ± 6.3 for non-fasted cycles in group A and 14.1 ± 5.6 for non-fasted and 11.0 ± 5.6 for fasted cycles in group B. There were no serious adverse effects. CONCLUSION STF during chemotherapy is well tolerated and appears to improve QOL and fatigue during chemotherapy. Larger studies should prove the effect of STF as an adjunct to chemotherapy. TRIAL REGISTRATION This trial was registered at clinicaltrials.gov: NCT01954836 .
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Effects of Fasting on 18F-DCFPyL Uptake in Prostate Cancer Lesions and Tissues with Known High Physiologic Uptake.
Wondergem, M, van der Zant, FM, Vlottes, PW, Knol, RJJ
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2018;59(7):1081-1084
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Prostate-specific membrane antigen (PSMA) (PSMA is a type II membrane protein)–targeted PET imaging is being increasingly applied in prostate cancer. The aim of this study was to determine the impact of fasting on 18F-DCFPyL (is a fluorine-18 labelled ligand binding specifically to PSMA) uptake in organs with known high physiologic uptake and in lesions characteristic of prostate cancer metastases. The study is a cohort study in which 50 and 48 patients were analysed in the fasting and non-fasting cohorts, respectively. Results showed that lesions characteristic of prostate cancer showed similar uptake in both the fasting and the non-fasting cohorts (number of lesions characteristic of prostate cancer totalled to 152 and 131 respectively). Authors conclude that fasting for up to 6 h before 18F-DCFPyL PET/CT does not significantly affect uptake in suspected malignant lesions but significantly lowers uptake in tissues with high physiologic uptake, such as the salivary glands, liver, and spleen.
Abstract
In the literature, a 4- to 6-h fast is recommended before a patient undergoes PET/CT with 2-(3-(1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid (18F-DCFPyL); however, a scientific underpinning for this recommendation is lacking. Therefore, we performed a study to determine the impact of fasting on 18F-DCFPyL uptake. Methods: The study included 50 patients who fasted at least 6 h before 18F-DCFPyL administration and 50 patients who did not. Activity (SUVmax) was measured in lesions characteristic of prostate cancer and in normal tissues known to express high physiologic uptake. Results: Uptake in suspected lesions did not differ between the cohorts. 18F-DCFPyL uptake in the submandibular gland, liver, and spleen was significantly higher in the fasting than the nonfasting cohort. Conclusion: Our data show that fasting does not significantly affect 18F-DCFPyL uptake in suspected malignant lesions but does result in significantly lower 18F-DCFPyL uptake in tissues with high physiologic uptake. The absolute differences in uptake were relatively small; therefore, the effects of fasting on the diagnostic performance can be considered negligible.
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A Pilot Study To Investigate the Immune-Modulatory Effects of Fasting in Steroid-Naive Mild Asthmatics.
Han, K, Nguyen, A, Traba, J, Yao, X, Kaler, M, Huffstutler, RD, Levine, SJ, Sack, MN
Journal of immunology (Baltimore, Md. : 1950). 2018;201(5):1382-1388
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Previous studies have shown that caloric restriction and fasting may modulate immune function and have positive effects in asthmatics. The aim of this pilot study was to evaluate the effects of fasting on specific inflammatory markers that might mediate such benefits. 18 mild asthmatics, 5 of whom were not on steroid inhalers, fasted for 24 hours. Lung function and immune parameters were evaluated at baseline and 2.5 hours after the first meal following the fast. There were significant differences between subjects who were and were not on steroid inhalers. Whilst one day of fasting did not affect lung function, a number of inflammatory parameters were improved by fasting in those not taking steroid inhalers, but not in those who were taking steroids. The authors conclude that caloric restriction might be considered as a strategy to improve systemic and pulmonary inflammation in asthma.
Abstract
A fasting mimetic diet blunts inflammation, and intermittent fasting has shown ameliorative effects in obese asthmatics. To examine whether canonical inflammatory pathways linked with asthma are modulated by fasting, we designed a pilot study in mild asthmatic subjects to assess the effect of fasting on the NLRP3 inflammasome, Th2 cell activation, and airway epithelial cell cytokine production. Subjects with documented reversible airway obstruction and stable mild asthma were recruited into this study in which pulmonary function testing (PFT) and PBMCextraction was performed 24 h after fasting, with repeated PFT testing and blood draw 2.5 h after refeeding. PFTs were not changed by a prolonged fast. However, steroid-naive mild asthmatics showed fasting-dependent blunting of the NLRP3 inflammasome. Furthermore, PBMCs from these fasted asthmatics cocultured with human epithelial cells resulted in blunting of house dust mite-induced epithelial cell cytokine production and reduced CD4+ T cell Th2 activation compared with refed samples. This pilot study shows that prolonged fasting blunts the NLRP3 inflammasome and Th2 cell activation in steroid-naive asthmatics as well as diminishes airway epithelial cell cytokine production. This identifies a potential role for nutrient level-dependent regulation of inflammation in asthma. Our findings support the evaluation of this concept in a larger study as well as the potential development of caloric restriction interventions for the treatment of asthma.
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A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial.
McKay, DL, Eliasziw, M, Chen, CYO, Blumberg, JB
Nutrients. 2018;10(3)
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There has been a global rise in cardiovascular disease (CVD) and type 2 diabetes mellitus (TD2M) and dietary risk factors are a known contributor. While evidence has shown that an increased intake of tree nuts is associated with a reduced risk of disease indicators, there is limited research specifically on the effects of pecans. The aim of this randomised crossover trial was to assess the impact of pecan consumption on biomarkers related to CVD and T2DM risk in 26 overweight or obese women. Participants consumed a pecan-rich diet with an iso-caloric control diet of similar fat and fibre content, but absent in nuts, for four weeks with a two-week washout period. This trial demonstrated that displacing a portion of saturated fat in the typical American diet with pecans has a protective effect for CVD and TD2M. Based on these results, the authors recommend using dietary change as a first-line approach to disease prevention and management and suggest further studies be done to better understand potential benefits and associated mechanisms.
Abstract
Evidence from observational and intervention studies has shown a high intake of tree nuts is associated with a reduced risk of cardiovascular disease (CVD), mortality from type 2 diabetes (T2DM), and all-cause mortality. However, there is limited data regarding their effects on indicators of cardiometabolic risk other than hypercholesterolemia, and little is known about the demonstrable health benefits of pecans (Carya illinoensis (Wangenh.) K.Koch). We conducted a randomized, controlled feeding trial to compare the effects of a pecan-rich diet with an isocaloric control diet similar in total fat and fiber content, but absent nuts, on biomarkers related to CVD and T2DM risk in healthy middle-aged and older adults who are overweight or obese with central adiposity. After 4 weeks on a pecan-rich diet, changes in serum insulin, insulin resistance (HOMA-IR) and beta cell function (HOMA-β) were significantly greater than after the control diet (p < 0.05). Pecan consumption also lowered the risk of cardiometabolic disease as indicated by a composite score reflecting changes in clinically relevant markers. Thus, compared to the control diet, the pecan intervention had a concurrent and clinically significant effect on several relevant markers of cardiometabolic risk.
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SunGold Kiwifruit Supplementation of Individuals with Prediabetes Alters Gut Microbiota and Improves Vitamin C Status, Anthropometric and Clinical Markers.
Wilson, R, Willis, J, Gearry, RB, Hughes, A, Lawley, B, Skidmore, P, Frampton, C, Fleming, E, Anderson, A, Jones, L, et al
Nutrients. 2018;10(7)
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Increased plasma glucose levels are linked with increased oxidative stress. An increase in the uptake of antioxidants such as vitamin C through diet has been demonstrated by several studies as contributing to the maintenance of normal glucose levels and reducing the risk factors for Type 2 diabetes. The aim of this study was to investigate the vitamin C status, anthropometric measurements and faecal microbiota of an individual on consumption of high vitamin C kiwi fruit for a period of 12 weeks. Baseline measures were compared at the end of 12 weeks resulting in significant increase in plasma vitamin C status (14 µmol/L, p < 0.001). Significant reduction in blood pressure measurement (4 mmHg, p = 0.029), reduction in waist- to- hip ratio and waist- circumference, decrease in blood glucose marker HbA1c (1 mmol/mol, p = 0.005) and increase in fasting glucose (0.1 mmol/L, p = 0.046) were also observed at the end of twelve weeks. Faecal microbiota composition showed an increase in the abundance of uncharacterised bacterial family. The authors concluded that these result were not sufficiently significant to draw conclusions and further studies with larger sample sizes are required to confirm the outcomes of this study.
Abstract
Kiwifruit are a nutrient dense food and an excellent source of vitamin C. Supplementation of the diet with kiwifruit enhances plasma vitamin C status and epidemiological studies have shown an association between vitamin C status and reduced insulin resistance and improved blood glucose control. In vitro experiments suggest that eating kiwifruit might induce changes to microbiota composition and function; however, human studies to confirm these findings are lacking. The aim of this study was to investigate the effect of consuming two SunGold kiwifruit per day over 12 weeks on vitamin C status, clinical and anthropometric measures and faecal microbiota composition in people with prediabetes. This pilot intervention trial compared baseline measurements with those following the intervention. Participants completed a physical activity questionnaire and a three-day estimated food diary at baseline and on completion of the trial. Venous blood samples were collected at each study visit (baseline, 6, 12 weeks) for determination of glycaemic indices, plasma vitamin C concentrations, hormones, lipid profiles and high-sensitivity C-reactive protein. Participants provided a faecal sample at each study visit. DNA was extracted from the faecal samples and a region of the 16S ribosomal RNA gene was amplified and sequenced to determine faecal microbiota composition. When week 12 measures were compared to baseline, results showed a significant increase in plasma vitamin C (14 µmol/L, p < 0.001). There was a significant reduction in both diastolic (4 mmHg, p = 0.029) and systolic (6 mmHg, p = 0.003) blood pressure and a significant reduction in waist circumference (3.1 cm, p = 0.001) and waist-to-hip ratio (0.01, p = 0.032). Results also showed a decrease in HbA1c (1 mmol/mol, p = 0.005) and an increase in fasting glucose (0.1 mmol/L, p = 0.046), however, these changes were small and were not clinically significant. Analysis of faecal microbiota composition showed an increase in the relative abundance of as yet uncultivated and therefore uncharacterised members of the bacterial family Coriobacteriaceae. Novel bacteriological investigations of Coriobacteriaceae are required to explain their functional relationship to kiwifruit polysaccharides and polyphenols.
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Melatonin Supplementation Lowers Oxidative Stress and Regulates Adipokines in Obese Patients on a Calorie-Restricted Diet.
Szewczyk-Golec, K, Rajewski, P, Gackowski, M, Mila-Kierzenkowska, C, Wesołowski, R, Sutkowy, P, Pawłowska, M, Woźniak, A
Oxidative medicine and cellular longevity. 2017;2017:8494107
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Obesity is one of the major global health problems. Melatonin is a hormone which regulates wakefulness, functions as an antioxidant and plays a role in the immune system. Previous research suggests that melatonin deficiency is associated with obesity. The aim of this study was to estimate the effect of melatonin on oxidative stress and levels of cell signalling proteins released by fat cells (adipokines) in obese patients on a calorie-restricted diet. Thirty obese patients were supplemented with a daily dose of 10 mg of melatonin or placebo for 30 days with a calorie-restricted diet. Blood levels of melatonin, adipokines and markers of oxidative stress were measured at baseline and after supplementation. Significant body weight reduction (7%) was observed only in the melatonin group. After melatonin supplementation, the adiponectin and omentin-1 levels and glutathione peroxidase activities statistically increased, whereas the malondialdehyde concentrations were reduced. In the placebo group, a significant rise in 4-hydroxynonenal and a drop in the melatonin concentrations were found. The results show evidence of increased oxidative stress accompanying calorie restriction. The authors concluded that melatonin supplementation facilitated body weight reduction, improved the antioxidant defence, and regulated adipokine secretion. The findings suggest that melatonin should be considered in the management of obesity.
Abstract
Obesity is one of the major global health problems. Melatonin deficiency has been demonstrated to correlate with obesity. The aim of the study was to estimate the effect of melatonin on oxidative stress and adipokine levels in obese patients on a calorie-restricted diet. Thirty obese patients were supplemented with a daily dose of 10 mg of melatonin (n = 15) or placebo (n = 15) for 30 days with a calorie-restricted diet. Serum levels of melatonin, 4-hydroxynonenal (HNE), adiponectin, omentin-1, leptin, and resistin, as well as erythrocytic malondialdehyde (MDA) concentration and Zn/Cu-superoxide dismutase, catalase, and glutathione peroxidase (GPx) activities, were measured at baseline and after supplementation. Significant body weight reduction was observed only in the melatonin group. After melatonin supplementation, the adiponectin and omentin-1 levels and GPx activities statistically increased, whereas the MDA concentrations were reduced. In the placebo group, a significant rise in the HNE and a drop in the melatonin concentrations were found. The results show evidence of increased oxidative stress accompanying calorie restriction. Melatonin supplementation facilitated body weight reduction, improved the antioxidant defense, and regulated adipokine secretion. The findings strongly suggest that melatonin should be considered in obesity management. This trial is registered with CTRI/2017/07/009093.
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Dietary Intake after Weight Loss and the Risk of Weight Regain: Macronutrient Composition and Inflammatory Properties of the Diet.
Muhammad, HFL, Vink, RG, Roumans, NJT, Arkenbosch, LAJ, Mariman, EC, van Baak, MA
Nutrients. 2017;9(11)
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In 2015, 107.7 million children and 603.7 million adults worldwide were obese. Effective actions to prevent the increasing rate of obesity and to treat those who are already obese are required. The aim of the study is to investigate the influence of macronutrients composition and inflammatory properties of the diet on weight regain during a weight maintenance period after weight loss of overweight and obese individuals. The study enrolled 57 Caucasian adult participants (27 males and 30 females) who had a body mass index more than 28kg/m2. The dietary intervention program consisted of three periods i.e. weight loss period, weight stable period and follow-up period. The study shows that the macronutrient composition of the weight maintenance diet was not associated with weight regain. However, the dietary inflammatory index was positively correlated with weight regain. In fact, intake of micronutrients with anti-inflammatory properties was found to be negatively correlated with weight regain. Authors conclude that the inflammatory properties of the diet during the weight maintenance period play a role in weight regain after a diet-induced weight loss program in overweight and obese adults.
Abstract
Weight regain after successful weight loss is a big problem in obesity management. This study aimed to investigate whether weight regain after a weight loss period is correlated with the macronutrient composition and/or the inflammatory index of the diet during that period. Sixty one overweight and obese adults participated in this experimental study. Subjects lost approximately 10% of their initial weight by means of very low-calorie diet for five weeks, or a low calorie diet for 12 weeks. After that, subjects in both groups followed a strict weight maintenance diet based on individual needs for four weeks, which was followed by a nine-month weight maintenance period without dietary counseling. Anthropometrics and dietary intake data were recorded before weight loss (baseline) and during the weight maintenance period. On average, participants regained approximately half of their lost weight. We found no evidence that macronutrient composition during the weight maintenance period was associated with weight regain. The dietary inflammatory index (r = 0.304, p = 0.032) was positively correlated with weight regain and remained significant after correction for physical activity (r = 0.287, p = 0.045). Our data suggest that the inflammatory properties of diet play a role in weight regain after weight loss in overweight and obese adults.
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Acid-base safety during the course of a very low-calorie-ketogenic diet.
Gomez-Arbelaez, D, Crujeiras, AB, Castro, AI, Goday, A, Mas-Lorenzo, A, Bellon, A, Tejera, C, Bellido, D, Galban, C, Sajoux, I, et al
Endocrine. 2017;58(1):81-90
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Very-low calorie ketogenic (VLCK) diets have been found to be an effective obesity treatment, however the acid-base safety of diet-induced ketosis is currently not known as ketone bodies are naturally acidic. The aim of this trial was to evaluate the acid-base status of 21 obese patients during the course of a VLCK diet. Participants followed a commercial weight loss program with physician supervision, and anthropometric and biochemical measures were taken at baseline and three subsequent visits. After four months of a VLCK diet the average weight loss among participants was 20.7 kg and all measured variables remained in the normal range, even at the point of maximum ketosis. Based on these results, the authors conclude a VLCK diet to be an effective and safe nutritional intervention in terms of acid-base balance.
Abstract
BACKGROUND AND AIMS Very low-calorie ketogenic (VLCK) diets have been consistently shown to be an effective obesity treatment, but the current evidence for its acid-base safety is limited. The aim of the current work was to evaluate the acid-base status of obese patients during the course of a VLCK diet. METHOD Twenty obese participants undertook a VLCK diet for 4 months. Anthropometric and biochemical parameters, and venous blood gases were obtained on four subsequent visits: visit C-1 (baseline); visit C-2, (1-2 months); maximum ketosis; visit C-3 (2-3 months), ketosis declining; and visit C-4 at 4 months, no ketosis. Results were compared with 51 patients that had an episode of diabetic ketoacidosis as well as with a group that underwent a similar VLCK diet in real life conditions of treatment. RESULTS Visit C1 blood pH (7.37 ± 0.03); plasma bicarbonate (24.7 ± 2.5 mmol/l); plasma glucose (96.0 ± 11.7 mg/l) as well as anion gap or osmolarity were not statistically modified at four months after a total weight reduction of 20.7 kg in average and were within the normal range throughout the study. Even at the point of maximum ketosis all variables measured were always far from the cut-off points established to diabetic ketoacidosis. CONCLUSION During the course of a VLCK diet there were no clinically or statistically significant changes in glucose, blood pH, anion gap and plasma bicarbonate. Hence the VLCK diet can be considered as a safe nutritional intervention for the treatment of obesity in terms of acid-base equilibrium.
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Roux-en-Y gastric bypass surgery of morbidly obese patients induces swift and persistent changes of the individual gut microbiota.
Palleja, A, Kashani, A, Allin, KH, Nielsen, T, Zhang, C, Li, Y, Brach, T, Liang, S, Feng, Q, Jørgensen, NB, et al
Genome medicine. 2016;8(1):67
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Roux-en-Y gastric bypass (RYGB) has been shown to cause quick and sustained weight loss, improvements to insulin sensitivity and reduced inflammation. However, the mechanisms resulting in these improvements are poorly understood. This longitudinal study explored the short and long term impact of RYGB on gut microbial composition with 13 morbidly obese people. The gut microbiomes were measured before surgery, and three months and 12 months after. Gut microbiota were categorised by species and gene levels. The study found that gut microbiota diversity increased in the first three months after RYGB surgery and still remained high 12 months later. This was inline with metabolic improvements (such as fasting blood glucose). There was also a change in microbiota composition including an increased potential for use of micro and macro nutrients.
Abstract
BACKGROUND Roux-en-Y gastric bypass (RYGB) is an effective means to achieve sustained weight loss for morbidly obese individuals. Besides rapid weight reduction, patients achieve major improvements of insulin sensitivity and glucose homeostasis. Dysbiosis of gut microbiota has been associated with obesity and some of its co-morbidities, like type 2 diabetes, and major changes of gut microbial communities have been hypothesized to mediate part of the beneficial metabolic effects observed after RYGB. Here we describe changes in gut microbial taxonomic composition and functional potential following RYGB. METHODS We recruited 13 morbidly obese patients who underwent RYGB, carefully phenotyped them, and had their gut microbiomes quantified before (n = 13) and 3 months (n = 12) and 12 months (n = 8) after RYGB. Following shotgun metagenomic sequencing of the fecal microbial DNA purified from stools, we characterized the gut microbial composition at species and gene levels followed by functional annotation. RESULTS In parallel with the weight loss and metabolic improvements, gut microbial diversity increased within the first 3 months after RYGB and remained high 1 year later. RYGB led to altered relative abundances of 31 species (P < 0.05, q < 0.15) within the first 3 months, including those of Escherichia coli, Klebsiella pneumoniae, Veillonella spp., Streptococcus spp., Alistipes spp., and Akkermansia muciniphila. Sixteen of these species maintained their altered relative abundances during the following 9 months. Interestingly, Faecalibacterium prausnitzii was the only species that decreased in relative abundance. Fifty-three microbial functional modules increased their relative abundance between baseline and 3 months (P < 0.05, q < 0.17). These functional changes included increased potential (i) to assimilate multiple energy sources using transporters and phosphotransferase systems, (ii) to use aerobic respiration, (iii) to shift from protein degradation to putrefaction, and (iv) to use amino acids and fatty acids as energy sources. CONCLUSIONS Within 3 months after morbidly obese individuals had undergone RYGB, their gut microbiota featured an increased diversity, an altered composition, an increased potential for oxygen tolerance, and an increased potential for microbial utilization of macro- and micro-nutrients. These changes were maintained for the first year post-RYGB. TRIAL REGISTRATION Current controlled trials (ID NCT00810823 , NCT01579981 , and NCT01993511 ).