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What is the Connection Between the Gut Microbiome and Body Weight?

The primary cause of weight gain is believed to occur when calorie intake is not used up, leaving the body to store the excess calories stored as fat, known as the “energy intake and expenditure” theory.

On top of this, evidence increasingly suggests that your own body’s internal community of microbes, referred to as the microbiome, could also be affecting your weight. So the connection between the gut microbiome and obesity warrants exploration.

Your gut microbes represent a very complex ecosystem and play many critical roles in the body. The colon or large intestine is the body region most heavily populated with microbes. The main activity of colonic microbes is fermenting dietary carbohydrates, harvesting around 10% of daily energy requirements1.

The bacteria in the gut aid food digestion. Being able to break down starches and fibre is not the only benefit; some gut bacteria produce beneficial compounds that support general gut health2, immunity 3,4 and are also shown to promote weight loss 5,6,7,8

,What Does Science Say About the Gut Microbiome and Obesity?

The link between gut microbes and obesity was first seen in studies on mice. It was noticed that sterile mice (bred in bacteria-free conditions) did not gain weight from a high-fat diet, even if their food intake was higher. However, in further experiments, when the microbes from obese mice were transferred into the bacteria-free mice, they gained much more weight compared to the mice that received bacterial transplants from lean mice 9,10,11,12,13.  This is pretty exciting stuff and it’s probably no surprise that the scientific community was interested in investigating the connections between gut microbes and body weight.

Studies have shown overweight people tend to have less diverse gut bacteria (less variety) than lean people 14,15,16,17,18. A large experiment with 154 pairs of twins showed that obese twins had lower diversity of their gut microbes compared to lean twins 19.

Also, the gut microbes of obese people show patterns of imbalance (dysbiosis) in comparison to people of normal weight. Dysbiosis is associated with different compositions of microbes meaning that you can have lower levels of beneficial bacteria and more opportunistic (or even pathogenic, or disease-causing) bacteria, which can impact the immune system and lead to weight gain 20,21,22.

Confirming what was found in the mouse studies, the composition of the gut microbiota varies in overweight compared to lean individuals. In particular, two important groups of bacteria that are prevalent in your gut are Bacteroidetes and Firmicutes. Like  mice obese humans also have a proportional increase of Firmicutes and lower Bacteroidetes. When this balance is tipped, noticeable weight loss has been demonstrated in people who are obese 23,24,25,26,27.

It seems that a key difference seen in obesity is the increased presence of bacteria with enzymes which can break down complex carbohydrates. This means the bacteria can extract more energy from the food – adding to energy excess, for storage as fat 28,29,30,31.

The Role of Antibiotics in the Gut Microbiome and Obesity

Industrial agriculture has known for decades that introducing antibiotics in low doses promotes weight gain in animals that are destined for meat consumption. Research on mice showed the same result: exposure to low doses of antibiotics early in life can lead to weight gain32. It is not unreasonable to hypothesise how current  food choices and antibiotic use early in life can lead to an increase in childhood obesity, as well as a weaker immune system.

Research has shown that when women take antibiotics during pregnancy, newborns had a higher birth weight33 and these children were 84% more likely to develop obesity by the age of seven34.

A recent review (2021) summarised the current evidence and concluded that antibiotics directly cause weight gain which leads to ichanges in the diversity of the gut microbiome and obesity is one possible result of that 35,36.

antibiotics influence gut microbiome and obesity risks

What Can You Do About It?

Therapies targeting gut microbes have become increasingly popular for weight loss and maintenance of a healthy weight.

While the gut microbiota of adults is relatively stable, it can fluctuate due to diet, lifestyle, medications, and other factors – often these are short-term changes41.

Researchers conclude that eating more fibre, fruits, vegetables, whole grains, and legumes directly promotes both diversity and abundance of microbes in the gut, linking to obesity prevention and sustained weight loss, as well as other potential health benefits 42,43,44,45.

Plant-based diets contain high amounts of prebiotic fibre, which feed and nourish beneficial gut bacteria. Recent studies have proven that eating natural plant-based food lowers the metabolic rate, and reduces calorie intake, supporting weight loss 37,38,39,40.

In summary, it is now recognised in the scientific community that gut microbiota influences weight balance. Healthy and sustainable weight loss can be achieved with healthy eating habits, with the focus on plant-based food rich in fibre. See the image below for where to get fibre from in your diet.

Fibre

Is Your Gut Microbiome Influencing Your Body Weight?

If you want to know if your gut microbiota might be influencing your weight, or your general health, make an appointment with Elena, or one of our team.

You can also order your stool microbiome test here.

REFERENCES CITED

  1. Macfarlane, G. T., & Macfarlane, S. (2011). Fermentation in the human large intestine: its physiologic consequences and the potential contribution of prebiotics. J Clin Gastroenterol.
  2. Koh, A., al. (2016). From dietary fiber to host physiology: Short-chain fatty acids as key bacterial metabolites. Cell.
  3. Ratajczak, W., et.al.  (2019). Immunomodulatory potential of gut microbiome-derived short-chain fatty acids (SCFAs). Acta Biochimica Polonica,
  4. Raheem, A., et.al. (2021). Modulatory effects of probiotics during pathogenic infections with emphasis on immune regulation. Front Immun.
  5. Davis, H. C. (2018). Can the gastrointestinal microbiota be modulated by dietary fibre to treat obesity? Ir J Med Sci .
  6. Cuevas-Sierra, A., et.al. (2019). Diet, gut microbiota, and obesity: links with host genetics and epigenetics and potential applications. Adv Nutr.
  7. Gérard P. (2016). Gut microbiota and obesity. Cell Mol Life Sci
  8. Torres-Fuentes, C., et.al. (2017). The microbiota-gut-brain axis in obesity. The Lancet. Gastro Hep,
  9. Bäckhed, F., et.al. (2007). Mechanisms underlying the resistance to diet-induced obesity in germ-free mice. PNAS.
  10. Turnbaugh, P. J., et.al. (2006). An obesity-associated gut microbiome with increased capacity for energy harvest. Nature
  11. Turnbaugh, P. J., et.al. (2008). Diet-induced obesity is linked to marked but reversible alterations in the mouse distal gut microbiome. Cell Host & Microbe.
  12. Ridaura, V. K., et.al. . (2013). Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science
  13. Vrieze, A., et al. (2012). Transfer of intestinal microbiota from lean donors increases insulin sensitivity in individuals with metabolic syndrome. Gastroenterol
  14. Xu, Z., & Knight, R. (2015). Dietary effects on human gut microbiome diversity. Br J Nutr.
  15. Ley, R. E., et.al. (2006). Human gut microbes associated with obesity. Nature.
  16. Patterson, E., et.al. (2016). Gut microbiota, obesity, and diabetes. PMJ.
  17. Le Chatelier, E., et.al. (2013). Richness of human gut microbiome correlates with metabolic markers. Nature.
  18. Marchesi, J. R., et.al.  (2016). The gut microbiota and host health: a new clinical frontier. Gut.
  19. Turnbaugh, P. J., et.al. (2009). A core gut microbiome in obese and lean twins. Nature.
  20. Hersoug, L. G., et.al. (2016). Gut microbiota‐derived lipopolysaccharide uptake and trafficking to adipose tissue: implications for inflammation and obesity. Obesity Reviews, 17(4), 297-312.
  21. Sun, L., et.al. (2018). Insights into the role of gut microbiota in obesity: pathogenesis, mechanisms, and therapeutic perspectives. Protein & cell, 9(5), 397-403.
  22. Patterson, E., et.al. (2016). Gut microbiota, obesity, and diabetes. Postgrad Med J, 92(1087), 286-300.
  23. Ley, R. E., et.al. (2006). Human gut microbes associated with obesity. Nature, 444(7122), 1022-1023.
  24. Ley, R. E., et.al.  (2005). Obesity alters gut microbial ecology. PNAS.
  25. Turnbaugh, P. J., & Gordon, J. I. (2009). The core gut microbiome, energy balance and obesity. The J Physiol.
  26. Finnicum, C. T., et al., (2018). Metataxonomic Analysis of Individuals at BMI Extremes and Monozygotic Twins Discordant for BMI. Twin Res Hum Gene.
  27. Walters, W. A., Xu, Z., & Knight, R. (2014). Meta-analyses of human gut microbes associated with obesity and IBD. FEBS Letters.
  28. Ley, R. E., et.al. (2006). Human gut microbes associated with obesity. Nature, 444(7122), 1022-1023.
  29. Jumpertz, R., et.al. (2011). Energy-balance studies reveal associations between gut microbes, caloric load, and nutrient absorption in humans. Am J Clin Nut, 94(1), 58-65.
  30. Turnbaugh, P. J., et.al. (2006). An obesity-associated gut microbiome with increased capacity for energy harvest. Nature, 444(7122), 1027-1031.
  31. Ley, R. E. (2010). Obesity and the human microbiome. Curr Op Gastroenterol, 26(1), 5-11.
  32. Cho, I., et.al. (2012) Antibiotics in early life alter the murine colonic microbiome and adiposity. Nature 488:621–626
  33. Jepsen, P., et.al. (2003). A population-based study of maternal use of amoxicillin and pregnancy outcome in Denmark. Brit J Clin Pharmacol
  34. Mueller, N. T., et al. (2015). Prenatal exposure to antibiotics, cesarean section and risk of childhood obesity. Int J Obes
  35. Vallianou, N., et.al. (2021). Do antibiotics cause obesity through long-term alterations in the gut microbiome? A review of current evidence. Curr Ob Rep.
  36. Klancic, T., & Reimer, R. A. (2020). Gut microbiota and obesity: Impact of antibiotics and prebiotics and potential for musculoskeletal health. J Sport Heal Sci.
  37. Nicolucci, A. C., et.al. (2017). Prebiotics reduce body fat and alter intestinal microbiota in children who are overweight or with obesity. Gastroenterology, 153(3), 711-722.
  38. Hume, M., et.al. (2017). Prebiotic supplementation improves appetite control in children with overweight and obesity: a randomized controlled trial. Am J Clin Nut
  39. Medawar, E., et.al. (2019). The effects of plant-based diets on the body and the brain: a systematic review. Translational Psychiatry, 9(1), 1-17.
  40. De Filippis, F., et.al. (2016). Unusual sub-genus associations of faecal Prevotella and Bacteroides with specific dietary patterns. Microbiome, 4(1), 1-6.
  41. Cotillard, A., et.al. (2013). Dietary intervention impact on gut microbial gene richness. Nature.
  42. Maldonado-Contreras, A., et.al . (2020). Associations between diet, the gut microbiome, and short-chain fatty acid production among older Caribbean Latino adults. J Acad Nutr Diet.
  43. Slavin J. L. (2005). Dietary fiber and body weight. Nutrition
  44. Menni, C., et.al. (2017). Gut microbiome diversity and high-fibre intake are related to lower long-term weight gain. Int J Obes, 41(7), 1099-1105.
  45. Angelakis, E., et.al.  (2012). The relationship between gut microbiota and weight gain in humans. 

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