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Bacteria Lactobacillus, 3D illustration. Normal flora of small intestine, lactic acid bacteria. Probiotic bacterium

Struggling to lose weight? This could be why!

You follow a healthy diet, you eat lots of salads, big bowls of vegetables and you say “no” to the piece of cake being offered at the office on most occasions… why then do you still never see the number of the scale move in the direction you’re hoping it will. And why does Jenny, who sits across from you eat whatever she pleases and is still able to maintain her weight?

The answer might surprise you.

Weight management: more that what you eat and how much you move

The digestive system is a complex one. At every part of the 9 metre long tract, one process kicks into another to ensure the food we eat is broken up, the nutrients made available to be absorbed, and that which is left over and we don’t need or use, is excreted as waste. While there are a number of chemical processes involved, which the body takes care of, there’s also another significant factor at play: your gut bacteria.

Within your digestive tract lives a 100 trillion-strong bacterial colony, which we collectively refer to as the microbiome, or gut flora, when paired with the other tiny organisms like fungi and viruses that live in the same environment.

While there are a small number of bacteria that inhabit the stomach and small intestine, the majority of the gut flora are located in the large intestine, which is densely populated. Research shows that there may be between 300-1000 different species of bacteria1, but only around 30-40 of these different species are most dominant2. These critters have many different functions, such as synthesizing vitamins, providing energy, and metabolizing compounds that your body is unable to 3.

In more recent years, as research in the field of the gut flora has developed, scientists have become interested in the role of these bacteria in weight management, and how different types of bacteria may be responsible for health imbalances and, in particular, metabolic diseases4. A clear link between the composition of the gut flora and type 2 diabetes, heart disease and obesity or overweight has been established.

The composition of the gut flora changes over time, being greatly influenced by factors within the environment, the foods you eat, your genetics and your overall state of health. A typical Westernized diet pattern has been found to negatively affect the gut bacteria and drives changes in the way the body uses energy from food5. These changes include those involving insulin sensitivity and the composition of fat cells in the body, which influences metabolism and energy balance.

Obesity, overweight and gut bacteria

We’ve always thought that our body shape is largely dictated by the genes we inherit, but this idea has been challenged. Evidence suggests that genetic variants only account for a small susceptibility to being overweight or developing obesity, and that it is the gut flora that may have a greater influence6. When the gut flora is not in balance, there is a huge shift in the way they interact with the rest of your body systems, which is a driver of disease7. There are several ways in which the gut flora affect the balance of health and contribute to overweight or obesity.

When researchers observed different types of gut flora in mice, they were able to determine just how much of an influence it has on energy balance. Mice raised without any gut flora have 40% less body fat than those mice with typical bacterial colonies. It remains true even when these mice eat almost 30% more calories than the conventionally-raised mice. Additionally, they appear to be protected from blood sugar imbalances and insulin resistance8.

When gut flora are pushed out of balance, so too, is energy balance and body weight. Changes in gut flora have been shown to:

  1. Increase calorie extraction from food by changing the lining of the small intestine and the movement of food through the digestive tract9.
  2. Influence carbohydrate digestion, which increases the amount of sugars available to be used or stored as energy10.
  3. Promote the deposit of fat into the liver, which is associated with obesity and non-alcoholic fatty liver disease6.
  4. Reduce the activation of a key compound that regulates insulin secretion, sugar uptake by cells and general energy balance11.

Diet plays a significant role in the composition of the gut flora and how it helps or hinders weight management efforts. Foods that trigger inflammation are believed to be partly responsible for changes in gut flora, promoting energy imbalance and overweight or obesity12. You already know that sugar, saturated fats, trans fats, and other chemically altered, processed and refined foods are a no-no when it comes to weight and that they should be eliminated from the diet, not only to lose weight but to promote overall health and wellbeing. General strategies to achieve this are to:

  • Eat more lean protein like chicken and turkey over fatty, red meat.
  • Choose healthier take-out options like salads, wraps and wholewheat sandwiches over burgers and other fat-rich fast food.
  • Reduce the need for packaged and processed foods by opting for fresh produce.
  • Switch out your regular sugary treats for natural sweet options like fruit.

These smart changes benefit your body in general, and nourish your healthy gut flora to promote them to grow and thrive.

On top of these standard dietary approaches to overweight and obesity, there is also evidence to show that using prebiotics can help to balance gut flora in an effort to reduce body mass and promote better blood sugar balance13. Prebiotic fibres could help to regulate appetite and promote weight loss because of its interaction with gut flora14. Did you know that the South American plant Smallanthus sonchifolius contains this healthy fibre? If you’ve ever heard of yacon syrup, it’s an extract from this plant that can act as a perfect addition to a healthy diet where it gives you the sweetness you’re looking for, while feeding your gut flora and helping with your weight management efforts15. It’s little wonder why the yacon plant has, for centuries, been used for its medicinal properties to help improve conditions like diabetes and digestive disorders16.

Then there are probiotics. These food supplements are known to improve intestinal balance by helping to change the current composition of the gut flora. Those that contain the species Bifidobacterium have been shown to improve blood sugar regulation and improve insulin sensitivity17.

We need to move away from believing it’s bad genes that sets us up for being overweight, obese or developing other metabolic diseases. Of course, genetics do play a role, however, with the proper maintenance of your gut flora, there’s improved utilization of the energy you obtain from your food. Use this to your advantage to better nourish your body and your gut flora, and allow it to help, not hinder, your weight loss efforts.

References:

  1. Guarner, F; Malagelada, J (2003). “Gut flora in health and disease”. The Lancet. 361 (9356): 512–19.
  2. Beaugerie, Laurent; Petit, Jean-Claude (2004). “Antibiotic-associated diarrhoea”. Best Practice & Research Clinical Gastroenterology. 18 (2): 337–52.
  3. Sherwood, Linda; Willey, Joanne; Woolverton, Christopher (2013). Prescott’s Microbiology (9th ed.). New York: McGraw Hill. pp. 713–21.
  4. Clarke, G, et al. (2014). “Minireview: Gut Microbiota: The Neglected Endocrine Organ”. Molecular Endocrinology. 28 (8): 1221–38.
  5. Boulangé, C, et al. (2016). “Impact of the gut microbiota on inflammation, obesity, and metabolic disease”. Genome Medicine. 8 (1): 42.
  6. Backhed F, et al. The gut microbiota as an environmental factor that regulates fat storage. Proc Natl Acad Sci U S A. 2004;101:15718–23.
  7. Marchesi J, et al. The gut microbiota and host health: a new clinical frontier. Gut. 2016;65:330–9.
  8. Turnbaugh P, et al. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006;444:1027–31
  9. Musso G., et al. Interactions between gut microbiota and host metabolism predisposing to obesity and diabetes. Annu Rev Med. 2011;62:361–80.
  10. Gibson G, et al. Dietary modulation of the human colonic microbiota: updating the concept of prebiotics. Nutr Res Rev. 2004;17:259–75
  11. Samuel B, et al. Effects of the gut microbiota on host adiposity are modulated by the short-chain fatty-acid binding G protein-coupled receptor, Gpr41. Proc Natl Acad Sci U S A. 2008;105:16767–72
  12. Cani P, et al. Changes in gut microbiota control metabolic endotoxemia‐induced inflammation in high‐fat diet‐induced obesity and diabetes in mice. Diabetes 2008;57:1470‐1481.
  13. Gibson G, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol 2017;14:491‐502.
  14. Cani P, et al. Inulin‐type fructans modulate gastrointestinal peptides involved in appetite regulation (glucagon‐like peptide‐1 and ghrelin) in rats. Br J Nutr 2004;92:521‐526.
  15. Genta, S., et al. Yacon syrup: beneficial effects on obesity and insulin resistance in humans. Clin Nutr. 2009 Apr;28(2):182-7.
  16. Aybar, M., et al. Hypoglycemic effect of the water extract of Smallantus sonchifolius (yacon) leaves in normal and diabetic rats. Journal of Ethnopharmacology. 2001. 74(2): 125-132.
  17. Saito I. Epidemiological evidence of type 2 diabetes mellitus, metabolic syndrome, and cardiovascular disease in Japan. Circ J. 2012;76:1066–73.

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