Open access peer-reviewed chapter

Gut Microbiome in Obesity Management

Written By

Hassan M. Heshmati

Submitted: October 21st, 2019 Reviewed: March 3rd, 2020 Published: April 16th, 2020

DOI: 10.5772/intechopen.91974

Chapter metrics overview

706 Chapter Downloads

View Full Metrics


Obesity is a worldwide pandemic causing increased morbidity/mortality and high cost for the society. Management of obesity requires multidisciplinary approaches including diet, food supplement, exercise, behavior change, drug, medical device, gut microbiome manipulation, and surgery. Over the past two decades, there has been a growing awareness of the importance of gut microbiome in human health and disease. Profound changes affecting the diversity and the abundance of gut microbiome are associated with several disorders including obesity. A decrease in microbiome diversity and an increase in the ratio of Firmicutes-to-Bacteroidetes phyla have been reported in obese subjects. The gut microbiome can be manipulated to change the host metabolism and manage obesity. Potential interventions include diet (e.g., low calories, low fat, and high fiber), prebiotics (e.g., inulin, lactulose, and resistant starch), probiotics (e.g., yogurt, cheese, and milk), synbiotics (combination of prebiotics and probiotics), bariatric surgery (e.g., Roux-en-Y gastric bypass), and fecal microbiota transplantation (through colonoscopy, esophagogastroduodenoscopy, orogastric tube, or oral capsule). A better understanding of the interactions between different diets and gut microbiome should help the development of new guidelines for the prevention and management of obesity.


  • gut microbiome
  • obesity
  • weight management

1. Introduction

Obesity is excess body weight for a given height, defined by a body mass index (BMI) ≥ 30 kg/m2. In some Asian countries (e.g., Japan), the threshold to define obesity is 25 kg/m2. The main cause of obesity is an imbalance between energy intake and energy expenditure. Obesity is a worldwide pandemic associated with increased morbidity/mortality and high cost for the society. The prevalence of obesity is increasing exponentially. The number of adult subjects with obesity is around 700 million worldwide. Near 4 million subjects die each year from the consequences of obesity. The annual cost of obesity is more than $2 trillion [1, 2, 3].

Management of obesity requires multidisciplinary approaches including diet, food supplement, exercise, behavior change, drug, medical device, gut microbiome manipulation, and surgery [1, 4, 5, 6, 7, 8, 9]. The annual obesity treatment market is around $6 billion.

The human intestine harbors a complex and diverse microbial ecosystem referred to as gut microbiome [10, 11, 12, 13, 14]. This rich community of microorganisms has co-evolved in a symbiotic relationship with humans. Its diversity is influenced by several factors including host genetics, mode of birth, age, gender, pregnancy, BMI, diet, medications, and surgery [12, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]. The understanding of the gut microbiome evolves at a rapid pace, but the practical application of this knowledge is still in its infancy. The gut microbiome is essential for the maintenance of human health. It is involved in protection against pathogens and regulation of immune system and metabolism [32]. Profound changes affecting the diversity and the abundance of gut microbiome (dysbiosis) are associated with several disorders including obesity [33]. The prevention and management of obesity may benefit from manipulation of gut microbiome.


2. Gut microbiome description and composition

Gut microbiome is a complex community of microorganisms living in the digestive tract, mainly in the colon (Figure 1). Variable pH and oxygen concentration affect the abundance of gut microbiome across the gastrointestinal tract. Gut microbiome represents up to 60% of the dry mass of feces (biomass around 1.5 kg), has more cells than host somatic cells and at least 100 times more genes than human genome [10, 11, 12, 13, 14].

Figure 1.

Gut microbiome is mainly located in the colon (Picture downloaded from the internet).

Gut microbiome is established within the few first years of life and contains up to 100 trillion microbes, mainly bacteria (more than 1,000 species) but also fungi, protozoa, archaea, and viruses. The taxonomic ranking of gut microbiome includes species, genera, families, orders, classes, and phyla. Most of the species belong to Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia phyla. The predominant phyla (90%) are Firmicutes (e.g., Ruminococcus and Lactobacillus genera) and Bacteroidetes (e.g., Bacteroides and Prevotella genera). Three enterotypes with functional differences have been defined based on variation in the level of genera: Enterotype 1 (Bacteroides), Enterotype 2 (Prevotella), and Enterotype 3 (Ruminococcus).


3. Gut microbiome projects

There are two major gut microbiome projects: European Megagenomics of the Human Intestinal Tract and US Human Microbiome Project [11]. For gut microbiome studies, multiple fecal collections of the same subject are recommended. The assessments are DNA-based methods (16S rDNA sequencing, whole genome shotgun sequencing) (Figure 2) [32, 34, 35]. The challenges in the assessments of gut microbiome are due to the diversity and the inter/intra-individual variability caused by different factors such as age and diet.

Figure 2.

Assessment of gut microbiome (Picture downloaded from the internet).


4. Gut microbiome metabolism

4.1 Nutrition sources

The sources for nutrition of gut microbiome are ingested dietary components (carbohydrate, protein, lipid) and host-derived components (shed epithelial cells, mucus).

4.2 Metabolites

Several metabolites are produced by gut microbiome. They include short-chain fatty acids (following carbohydrate fermentation), phenolic substances (following protein fermentation), and vitamins (vitamin B, vitamin K).


5. Gut microbiome changes

Gut microbiome is diverse, varies between individuals, and can fluctuate over time. Western gut microbiome has less species than non-Western gut microbiome.

In addition to several pathological conditions that can alter gut microbiome composition, multiple factors are responsible for the changes in gut microbiome (Figure 3) [12, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31].

Figure 3.

Multiple factors can impact gut microbiome (Picture downloaded from the Internet).

5.1 Host genetics

There are possible relations between host genetic profile and gut microbiome composition, but additional studies are needed for a better understanding of these relations [15].

5.2 Mode of birth

Mode of birth has an important influence on gut microbiome composition [12, 16]. With vaginal delivery, infants are colonized by maternal vaginal bacteria (dominated by Lactobacillus and Prevotella genera) while following C-section delivery, infants are colonized by maternal skin bacteria (dominated by Staphylococcus, Corynebacterium, and Propionibacterium genera).

5.3 Age

Age is associated with important changes in gut microbiome [12, 17]. The changes occur mainly before 20 and after 70 years. The diet plays a significant role. In preterm infants, there is a predominance of Proteobacteria phylum. There are marked changes in infants. The choice of diet after birth (breast milk or formula milk) affects the colonization process in the newborn. With age, the introduction of solid food from 2 years and the production of sex hormones from puberty (to menopause in females) bring additional richness and complexity to gut microbiome. There is a relative stability of gut microbiome between 20 and 70 years (predominance of Firmicutes phylum). In elderly subjects, Bacteroidetes phylum is predominant.

5.4 Gender

Gender specificity of gut microbiome appears at puberty with the production of sex hormones [12, 18]. There is a lower abundance of Bacteroidetes phylum in women (role of estrogen).

5.5 Pregnancy

Elevated levels of estrogen and progesterone observed during pregnancy have important impact on gut microbiome [12, 16, 19]. The changes are characterized by a decrease in richness of gut microbiome, a higher abundance of Proteobacteria and Actinobacteria phyla, a decrease in Faecalibacterium genus, and an increase in Firmicutes-to-Bacteroidetes phyla ratio.

5.6 BMI

BMI is associated with gut microbiome composition particularly in women [18]. Bacteroidetes phylum is less abundant in subjects with high BMI. The role of estrogen has been proposed.

5.7 Diet

Diet has an important influence on gut microbiome composition [20, 21, 22, 23, 24, 25]. However, there is a high interindividual variability. A diet high in fat (≥ 55% of total macronutrients) is associated with increased Firmicutes and Proteobacteria phyla and decreased Bacteroidetes phylum while a diet rich in fiber (≥ 30 g/day) has the opposite effect. The changes in gut microbiome (composition and functionality) induced by diet can be observed as early as 2 days. However, major changes in gut microbiome require long-term change in dietary habits.

Important differences in gut microbiome have been reported in children between Europe and rural African village of Burkina Faso (polysaccharide-rich diet) with Firmicutes-to-Bacteroidetes phyla ratios of 2.8 and 0.5, respectively [26].

Diet may also contribute to the seasonal variations of gut microbiome likely due to different availability of fresh produce containing complex carbohydrates [27].

5.8 Medication

Several medications (e.g., antibiotics, nonsteroidal anti-inflammatory drugs, proton pump inhibitors, and metformin) affect gut microbiome [28, 29, 30]. The use of antibiotics is associated with increased Firmicutes phylum, with higher sensitivity in infants.

The impact of prebiotics and probiotics on gut microbiome is presented in Section 8.

5.9 Surgery

Since colon is the main reservoir of gut microbiome, surgical removal of colon may affect gut microbiome [31]. Indeed, right hemicolectomy for colorectal cancer has been reported to be associated with a decrease in diversity and richness of gut microbiome.

The impact of bariatric surgery on gut microbiome is presented in Section 8.


6. Gut microbiome functions

The gut microbiome is involved in multiple physiological functions (Table 1) [32, 36, 37, 38, 39, 40, 41].

Function of gut microbiomeMechanism and target
ProtectionKilling or inhibiting unwanted organisms competing for nutrients
Immune systemInfluencing production of cytokines and antibodies
MetabolismRegulating energy homeostasis, producing short-chain fatty acids and vitamins, impacting glycemic control, interacting with incretins, regulating metabolism of lipids and bone

Table 1.

Physiological functions of gut microbiome.

6.1 Protection against pathogens

Gut microbiome can protect against pathogens by killing or inhibiting unwanted organisms (e.g., Clostridium difficile genera) that are competing for nutrients.

6.2 Regulation of immune system

Gut microbiome regulates immune system by influencing the production of cytokines and antibodies.

6.3 Regulation of metabolism

Gut microbiome is involved in several metabolic processes. These processes include regulation of energy homeostasis and body weight, production of short-chain fatty acids (following fermentation of nondigestible fibers) and vitamins (vitamins B, vitamin K) [32, 36], glycemic control [37, 38], interaction with incretins [39], and metabolism of lipids [40] and bone [41].


7. Gut microbiome in diseases

Dysbiosis is observed in several medical conditions including obesity, malnutrition, type 2 diabetes, inflammatory bowel diseases, neurological disorders, and cancer [33, 42, 43, 44, 45, 46, 47, 48]. The dysbiosis can be the cause and/or the consequence of these diseases.

Gut microbiome influences drug pharmacokinetics and bioavailability, and thus, affects the efficacy and safety of several drugs used to treat diseases [49].


8. Gut microbiome and obesity

8.1 Gut microbiome composition in obesity

Although there are some conflicting data, most studies have reported that in obesity, there is a lower gut microbiome diversity, a higher abundance of Firmicutes phylum, a lower abundance of Bacteroidetes phylum, and a higher Firmicutes-to-Bacteroidetes phyla ratio [33, 42, 43, 44, 45]. There is also a higher abundance of Lactobacillus (genus belonging to Firmicutes phylum).

According to most studies, the low-grade inflammation stimulated by lipopolysaccharide production is the prime mechanism by which gut microbiome induces obesity [50].

8.2 Gut microbiome in obesity management

Gut microbiome can be manipulated for the purpose of obesity management using different tools (Table 2) [20, 21, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60].

8.2.1 Diet

Diet is an important factor for the manipulation of gut microbiome and management of obesity. The amount of daily caloric intake and the content of food significantly affect gut microbiome but with high interindividual variability [20, 21, 51]. A diet that is low in calories, low in fat (< 20% of total macronutrients), and high in fiber (≥ 30 g/day) has a favorable effect on gut microbiome (increase in richness, decrease in Firmicutes-to-Bacteroidetes phyla ratio) and weight control (weight loss).

8.2.2 Prebiotics

Prebiotics are chemicals (nondigestible food ingredients) inducing growth and/or activity of bacteria [50, 52]. Prebiotics must be able to resist gastric acidity, resist enzymatic hydrolysis, resist absorption in the upper gastrointestinal tract, and be fermentable by the gut microbiome. Examples are inulin, lactulose, and resistant starch. Prebiotics can be found in many foods (e.g., leek, asparagus, onion, and soybean).

By modulating gut microbiome and lowering the production of lipopolysaccharide, prebiotics have the potential to manage obesity. In a double-blind, placebo-controlled clinical study, administration of oligofructose-enriched inulin (8 g/day) to overweight/obese children for 16 weeks caused a significant increase in Bifidobacterium (genus belonging to Actinobacteria phylum) and significantly slowed the body weight gain compared with placebo [53].

8.2.3 Probiotics

Probiotics are nonpathogenic living microorganisms with direct or indirect effect on gut microbiome [50, 54, 55]. Products containing probiotics should be tested for safety risks before marketing. Probiotics can be found in several foods (e.g., yogurt, cheese, and milk).

Probiotics can manage obesity by reducing the production of lipopolysaccharide through an impact on gut microbiome. In a double-blind, placebo-controlled clinical study, administration of fermented milk containing Lactobacillus gasseri species (LG2055) to overweight/obese adults for 12 weeks caused a significant decrease in body weight [56].

8.2.4 Synbiotics

Synbiotics are combination of prebiotics and probiotics. They have the potential to induce more effects on gut microbiome and body weight than prebiotics or probiotics alone.

8.2.5 Bariatric surgery

Bariatric surgery can modify gut microbiome and further affect body weight [57, 58]. The mechanisms include reduced caloric intake, reduced gastric emptying, and alterations in gastric acid production and bile acids.

After Roux-en-Y gastric bypass surgery in obese subjects, there is a decrease in Firmicutes-to-Bacteroidetes phyla ratio and an increase in Proteobacteria phylum [57, 58].

8.2.6 Fecal microbiota transplantation

Fecal microbiota transplantation, which consists of transfer of feces from a healthy donor to a recipient, is an exciting therapy with important potential. It can modify gut microbiome for the purpose of obesity management [59, 60]. The addition of healthy stool can be done through colonoscopy, orogastric tube, esophagogastroduodenoscopy, or oral capsule. It is important to carefully select and screen the donor to avoid risk of infection, aggravation of obesity, or other complications [61, 62].

Available clinical data are very preliminary and limited. Several studies are ongoing. There is no regulatory guidance for the use of fecal microbiota transplantation in the management of obesity.

8.2.7 Cost of gut microbiome manipulation

Cost of gut microbiome manipulation in obesity management is reported in Table 3.

Tool for gut microbiome manipulationDescription
DietLow calories, low fat, high fiber
PrebioticsInulin, lactulose, resistant starch
ProbioticsYogurt, cheese, milk
SynbioticsCombination of prebiotics and probiotics
Bariatric surgeryRoux-en-Y gastric bypass
Fecal microbiota transplantationAddition of healthy stool

Table 2.

Different tools used for gut microbiome manipulation in obesity management.

Tool for gut microbiome manipulationAverage cost (range)
DietCost of food
Prebiotics< $100/month
Probiotics< $100/month
Synbiotics< $100/month
Bariatric surgery (Roux-en-Y gastric bypass)$23,000 ($20,000–$30,000)
Fecal microbiota transplantation$1,800 ($1,600–$2,000) + cost of administration/dose

Table 3.

Cost of different tools used for gut microbiome manipulation in obesity management in the USA.

8.3 Gut microbiome after weight loss

After successful weight loss, there is a decrease in Firmicutes phylum, an increase in Bacteroidetes phylum, and a decrease of Firmicutes-to-Bacteroidetes phyla ratio [45, 51, 57, 58].


9. Clinical study design to assess gut microbiome in obesity

Well-designed clinical studies are urgently needed to better understand the interactions between obesity/obesity treatment and gut microbiome.

Several factors affect the quality of weight-loss studies aimed to assess gut microbiome. A well-calculated sample size allowing subgroup analysis is a key factor. Relevant stratification factors (e.g., race, age, gender, BMI, diet, and medications) at randomization will make the study more informative. Any underestimation of these stratification factors, as it has been the case in several clinical studies, especially in relation to diet and medications, may lead to misleading and conflicting results. The duration of the clinical studies has to be sufficient to allow both short-term and long-term/follow-up assessments. Adequate adjustments should be made during the statistical analysis.


10. Ideal gut microbiome

An ideal gut microbiome should have high diversity. At the level of phyla, the ideal gut microbiome should have low Firmicutes phylum and high Bacteroidetes phylum with a Firmicutes-to-Bacteroidetes phyla ratio < 1.0. At the level of genera, the ideal gut microbiome should be rich in Prevotella genus.

The recommended diet to reach the above objectives is a diet adequate in calories (adjusted to the activity), low in fat (< 20% of total macronutrients), and rich in fiber (≥ 30 g/day).

11. Conclusions

Gut microbiome influences normal physiology and susceptibility to diseases. Profound changes affecting the diversity and the abundance of gut microbiome are associated with obesity. A decrease in microbiome diversity and an increase in the ratio of Firmicutes-to-Bacteroidetes phyla have been reported in obese subjects.

Gut microbiome can be manipulated to change the host metabolism and manage obesity. Potential interventions include diet, prebiotics, probiotics, synbiotics, bariatric surgery, and fecal microbiota transplantation.

A better understanding of the interactions between different diets and gut microbiome should help the development of new guidelines for feeding humans to prevent or manage obesity.

Conflict of interest

The author received honorarium for consultancy from Gelesis, Inc.


  1. 1. Gadde KM, Martin CK, Berthoud HR, Heymsfield SB. Obesity. Pathophysiology and management. Journal of the American College of Cardiology. 2018;71:69-84. DOI: 10.1016/j.jacc.2017.11.011
  2. 2. GBD 2015 Obesity Collaborators, Afshin A, Forouzanfar MH, Reitsma MB, et al. Health effects of overweight and obesity in 195 countries over 25 years. The New England Journal of Medicine. 2017;377:13-27. DOI: 10.1056/NEJMoa1614362
  3. 3. Shephard RJ. On determining how much obesity is costing society. The Health & Fitness Journal of Canada. 2019;12:80-116. DOI: 10.14288/hfjc.v12i1.276
  4. 4. Freedman MR, King J, Kennedy E. Popular diets: A scientific review. Obesity Research. 2001;9(Suppl 1):1S-40S
  5. 5. Onakpoya IJ, Wider B, Pittler MH, Ernst E. Food supplements for body weight reduction: A systematic review of systematic reviews. Obesity. 2011;19:239-244. DOI: 10.1038/oby.2010.185
  6. 6. Wadden TA, Butryn ML, Hong PS, Tsai AG. Behavioral treatment of obesity in patients encountered in primary care settings. A systematic review. Journal of the American Medical Association. 2014;312:1779-1791. DOI: 10.1001/jama.2014.14173
  7. 7. Saxon DR, Iwamoto SJ, Mettenbrink CJ, et al. Antiobesity medication use in 2.2 million adults across eight large health care organizations: 2009-2015. Obesity. 2019;27:1975-1981. DOI: 10.1002/oby.22581
  8. 8. Lee PC, Dixon J. Medical devices for the treatment of obesity. Nature Reviews. Gastroenterology & Hepatology. 2017;14:553-564. DOI: 10.1038/nrgastro.2017.80
  9. 9. Radvinsky D, Iskandar M, Ferzli G. Bariatric surgery today: The good, the bad, and the ugly. Annals of Laparoscopic and Endoscopic Surgery. 2017;2:52. DOI: 10.21037/ales.2017.02.26
  10. 10. The Human Microbiome Project Consortium. Structure, function and diversity of the healthy human microbiome. Nature. 2012;486:207-214. DOI: 10.1038/nature11234
  11. 11. Lozupone CA, Stombaugh JI, Gordon JI, Jansson JK, Knight R. Diversity, stability and resilience of the human gut microbiota. Nature. 2012;489:220-230. DOI: 10.1038/nature11550
  12. 12. Kundu P, Blacher E, Elinav E, Pettersson S. Our gut microbiome: The evolving inner self. Cell. 2017;171:1481-1493. DOI: 10.1016/j.cell.2017.11.024
  13. 13. Barko PC, McMichael MA, Swanson KS, Williams DA. The gastrointestinal microbiome: A review. Journal of Veterinary Internal Medicine. 2018;32:9-25. DOI: 10.1111/jvim.14875
  14. 14. Schmidt TSB, Raes J, Bork P. The human gut microbiome: From association to modulation. Cell. 2018;172:1198-1215. DOI: 10.1016/j.cell.2018.02.044
  15. 15. Dąbrowska K, Witkiewicz W. Correlations of host genetics and gut microbiome composition. Frontiers in Microbiology. 2016;7:1357. DOI: 10.3389/fmicb.2016.01357
  16. 16. Nuriel-Ohayon M, Neuman H, Koren O. Microbial changes during pregnancy, birth, and infancy. Frontiers in Microbiology. 2016;7:1031. DOI: 10:3389/fmicb.2016.01031
  17. 17. Odamaki T, Kato K, Sugahara H, et al. Age-related changes in gut microbiota composition from newborn to centenarian: A cross-sectional study. BMC Microbiology. 2016;16:90. DOI: 10.1186/s12866-016-0708-5
  18. 18. Dominianni C, Sinha R, Goedert JJ, et al. Sex, body mass index, and dietary fiber intake influence the human gut microbiome. PLoS One. 2015;10:e0124599. DOI: 10.1371/journal.pone.0124599
  19. 19. Edwards SM, Cunningham SA, Dunlop AL, Corwin EJ. The maternal gut microbiome during pregnancy. MCN: The American Journal of Maternal/Child Nursing. 2017;42:310-317. DOI: 10.1097/NMC.0000000000000372
  20. 20. Wu GD, Chen J, Hoffmann C, et al. Linking long-term dietary patterns with gut microbial enterotypes. Science. 2011;334:105-108. DOI: 10.1126/science.1208344
  21. 21. Moschen AR, Wieser V, Tilg H. Dietary factors: Major regulators of the gut’s microbiota. Gut and Liver. 2012;6:411-416. DOI: 10.5009/gnl.20126.4.411
  22. 22. David LA, Maurice CF, Carmody RN, et al. Diet rapidly and reproducibly alters the human gut microbiome. Nature. 2014;505:559-563. DOI: 10.1038/nature12820
  23. 23. Graf D, Di Cagno R, Fåk F, et al. Contribution of diet to the composition of the human gut microbiota. Microbial Ecology in Health and Disease. 2015;26:26164. DOI: 10.3402/mehd.v26.26164
  24. 24. Bibbò S, Ianiro G, Giorgio V, et al. The role of diet on gut microbiota composition. European Review for Medical and Pharmacological Sciences. 2016;20:4742-4749
  25. 25. Singh RK, Chang HW, Yan D, et al. Influence of diet on the gut microbiome and implications for human health. Journal of Translational Medicine. 2017;15:73. DOI: 10.1186/s12967-017-1175-y
  26. 26. De Filippo C, Cavalieri D, Di Paola M, et al. Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. PNAS. 2010;107:14691-14696. DOI: 10.1073/pnas.1005963107
  27. 27. Davenport ER, Mizrahi-Man O, Michelini K, Barreiro LB, Ober C, Gilad Y. Seasonal variation in human gut microbiome composition. PLoS One. 2014;9:e90731. DOI: 10.1371/journal.pone.0090731
  28. 28. Raymond F, Ouameur AA, Déraspe M, et al. The initial state of the human gut microbiome determines its reshaping by antibiotics. The ISME Journal. 2016;10:707-720. DOI: 10.1038/ismej.2015.148
  29. 29. Maier L, Pruteanu M, Kuhn M, et al. Extensive impact of non-antibiotic drugs on human gut bacteria. Nature. 2018;555:623-628. DOI: 10.1038/nature25979
  30. 30. Le Bastard Q , Al-Ghalith GA, Grégoire M, et al. Systematic review: Human gut dysbiosis induced by non-antibiotic prescription medications. Alimentary Pharmacology & Therapeutics. 2018;47:332-345. DOI: 10.1111/apt.14451
  31. 31. Lin XH, Jiang JK, Luo JC, et al. The long term microbiota and metabolic status in patients with colorectal cancer after curative colon surgery. PLoS One. 2019;14:e0218436. DOI: 10.1371/journal.pone.0218436
  32. 32. Conrad R, Vlassov AV. The human microbiota: Composition, functions, and therapeutic potential. Medical Science Review. 2015;2:92-103. DOI: 10.12659/MSRev.895154
  33. 33. Holmes E, Li JV, Athanasiou T, Ashrafian H, Nicholson JK. Understanding the role of gut microbiome-host metabolic signal disruption in health and disease. Trends in Microbiology. 2011;19:349-359. DOI: 10.1016/j.tim.2011.05.006
  34. 34. Ji B, Nielsen J. From next-generation sequencing to systematic modeling of the gut microbiome. Frontiers in Genetics. 2015;6:219. DOI: 10.3389/fgene.2015.00219
  35. 35. Magnúsdόttir S, Thiele I. Modeling metabolism of the human gut microbiome. Current Opinion in Biotechnology. 2018;51:90-96. DOI: 10.1016/j.copbio.2017.12.005
  36. 36. Ramakrishna BS. Role of the gut microbiota in human nutrition and metabolism. Journal of Gastroenterology and Hepatology. 2013;28(Suppl 4):9-17. DOI: 10.1111/jgh.12294
  37. 37. Kovatcheva-Datchary P, Nilsson A, Akrami R, et al. Dietary fiber-induced improvement in glucose metabolism is associated with increased abundance of Prevotella. Cell Metabolism. 2015;22:971-982. DOI: 10.1016/j.cmet.2015.10.001
  38. 38. Gerard C, Vidal H. Impact of gut microbiota on host glycemic control. Frontiers in Endocrinology. 2019;10:29. DOI: 10.3389/fendo.2019.00029
  39. 39. Covasa M, Stephens RW, Toderean R, Cobuz C. Intestinal sensing by gut microbiota: Targeting gut peptides. Frontiers in Endocrinology. 2019;10:82. DOI: 10.3389/fendo.2019.00082
  40. 40. Fu J, Bonder MJ, Cenit MC. The gut microbiome contributes to a substantial proportion of the variation in blood lipids. Circulation Research. 2015;117:817-824. DOI: 10.1161/CIRCRESAHA.115.306807
  41. 41. Chen YC, Greenbaum J, Shen H, Deng HW. Association between gut microbiota and bone health: Potential mechanisms and prospective. The Journal of Clinical Endocrinology and Metabolism. 2017;102:3635-3646. DOI: 10.1210/jc.2017-00513
  42. 42. Hartstra AV, Bouter KEC, Bäckhed F, Nieuwdorp M. Insights into the role of the microbiome in obesity and type 2 diabetes. Diabetes Care. 2015;38:159-165. DOI: 10.2337/dc14-0769
  43. 43. Harakeh SM, Khan I, Kumosani T, et al. Gut microbiota: A contributing factor to obesity. Frontiers in Cellular and Infection Microbiology. 2016;6:95. DOI: 10.3389/fcimb.2016.00095
  44. 44. Davis CD. The gut microbiome and its role in obesity. Nutrition Today. 2016;51:167-174. DOI: 10.1097/0000000000000167
  45. 45. Meijnikman AS, Gerdes VE, Nieuwdorp M, Herrema H. Evaluating causality of gut microbiota in obesity and diabetes in humans. Endocrine Reviews. 2018;39:133-153. DOI: 10.1210/er.2017-00192
  46. 46. Lambeth SM, Carson T, Lowe J, et al. Composition, diversity and abundance of gut microbiome in prediabetes and type 2 diabetes. Journal of Diabetes and Obesity. 2015;2:1-7. DOI: 10.15436/2376-0949.15.031
  47. 47. Brunkwall L, Orho-Melander M. The gut microbiome as a target for prevention and treatment of hyperglycaemia in type 2 diabetes: From current human evidence to future possibilities. Diabetologia. 2017;60:943-951. DOI: 10.1007/s00125-017-4278-3
  48. 48. Hamada T, Nowak JA, Milner DA Jr, Song M, Ogino S. Integration of microbiology, molecular pathology, and epidemiology: A new paradigm to explore the pathogenesis of microbiome-driven neoplasms. Journal of Pathology. 2019;247:615-628. DOI: 10.1002/path.5236
  49. 49. Enright EF, Gahan CGM, Joyce SA, Griffin BT. The impact of the gut microbiota on drug metabolism and clinical outcome. Yale Journal of Biology and Medicine. 2016;89:375-382
  50. 50. Dahiya DK, Renuka, Puniya M, et al. Gut microbiota modulation and its relationship with obesity using prebiotics fibers and probiotics: A review. Frontiers in Microbiology. 2017;8:563. DOI: 10.3389/fmicb.2017.00563
  51. 51. Voreades N, Kozil A, Weir TL. Diet and the development of the human intestinal microbiome. Frontiers in Microbiology. 2014;5:494. DOI: 10.3389/fmicb.2014.00494
  52. 52. Carnahan S, Balzer A, Panchal SK, Brown L. Prebiotics in obesity. Panminerva Medica. 2014;56:165-175
  53. 53. Nicolucci AC, Hume MP, Martínez I, Mayengbam S, Walter J, Reimer RA. Prebiotics reduce body fat and alter intestinal microbiota in children who are overweight or with obesity. Gastroenterology. 2017;153:711-722. DOI: 10.1053/j.gastro.2017.05.055
  54. 54. Hill C, Guarner F, Reid G, et al. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews. Gastroenterology & Hepatology. 2014;11:506-514. DOI: 10.1038/nrgastro.2014.66
  55. 55. Kobyliak N, Conte C, Cammarota G, et al. Probiotics in prevention and treatment of obesity: A critical view. Nutrition and Metabolism. 2016;13:14. DOI: 10.1186/s12986-016-0067-0
  56. 56. Kadooka Y, Sato M, Imaizumi K, et al. Regulation of abdominal adiposity by probiotics (Lactobacillus gasseri SBT2055) in adults with obese tendencies in a randomized controlled trial. European Journal of Clinical Nutrition. 2010;64:636-643. DOI: 10.1038/ejcn.2010.19
  57. 57. Furet JP, Kong LC, Tap J, et al. Differential adaptation of human gut microbiota to bariatric surgery-induced weight loss. Links with metabolic and low-grade inflammation markers. Diabetes. 2010;59:3049-3057. DOI: 10.2337/db10-0253
  58. 58. Sweeney TE, Morton JM. The human gut microbiome. A review of the effect of obesity and surgically induced weight loss. JAMA Surgery. 2013;148:563-569. DOI: 10.1001/jamasurg.2013.5
  59. 59. Jayasinghe TN, Chiavaroli V, Holland DJ, Cutfield WS, O’Sullivan JM. The new era of treatment for obesity and metabolic disorders: Evidence and expectations for gut microbiome transplantation. Frontiers in Cellular and Infection Microbiology. 2016;6:15. DOI: 10.3389/fcimb.2016.00015
  60. 60. Marotz CA, Zarrinpar A. Treating obesity and metabolic syndrome with fecal microbiota transplantation. Yale Journal of Biology and Medicine. 2016;89:383-388
  61. 61. Woodworth MH, Carpentieri C, Sitchenko KL, Kraft CS. Challenges in fecal donor selection and screening for fecal microbiota transplantation: A review. Gut Microbes. 2017;8:225-237. DOI: 10.1080/19490976.2017.1286006
  62. 62. Wang S, Xu M, Wang W, et al. Systematic review: Adverse events of fecal microbiota transplantation. PLoS One. 2016;11:e0161174. DOI: 10.1371/journal.pone.0161174

Written By

Hassan M. Heshmati

Submitted: October 21st, 2019 Reviewed: March 3rd, 2020 Published: April 16th, 2020