How GI Bacteria Affect Weight

Stress plays a bigger role in obesity than many people realize. Some stressors are obvious, but others are difficult to trace, like intestinal bacteria that contribute to high blood pressure, diabetes, and weight gain.

Mental and emotional stress triggers the release of adrenal hormones, like cortisol and adrenaline. These hormones stimulate the vagus nerve, a vital pathway between the brain, heart, lungs, and gut. The tie between our brain and gut is a two-way street. Stress affects digestion, and poor digestion makes us feel more stressed. Stress reduces the blood supply needed to properly digest foods and balance bacteria. When this vicious cycle gets rolling, it wipes out Bacteroidetes. Bacteroidetes maintain gut barrier integrity, protecting against invaders and supporting metabolism. When they run low, there’s a greater risk of digestive and metabolic disorders.¹Durack J, Lynch SV. The gut microbiome: relationships with disease and opportunities for therapy. J Exp Med. 2019 Jan 7;216(1):20-40. https://doi.org/10.1084/jem.20180448

Anaerobes and weight management

Ninety-nine percent of the bacteria in our GI tract are anaerobes, which cannot use oxygen. Foods like sauerkraut and yogurt, as well as probiotic supplements, contain bacteria that require oxygen to grow. They have little to no effect on the anaerobes that run the show.

Two of the many types of anaerobes most directly correlated with obesity are Bacteroidetes and Firmicutes. These bacteria affect weight by regulating fat absorption. People with lower Bacteroidetes-to-Firmicutes ratios may be more likely to gain weight.

How to cultivate a healthier gut

Diet, nutrition, and regular good habits are the crux of a well-functioning digestive system. There are four ways to quickly build a microbiome protected from inflammation and outside invaders:

1. Prioritize healthy fats and complex carbs. Higher-fat diets could support Bacteroides, whereas diets high in simple carbohydrates may increase Firmicutes populations²Wu GD, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA, Bewtra M, Knights D, Walters WA, Knight R, Sinha R, Gilroy E, Gupta K, Baldassano R, Nessel L, Li H, Bushman FD, Lewis JD. Linking long-term dietary patterns with gut microbial enterotypes. Science. 2011 Oct 7;334(6052):105-8. https://doi.org/10.1126/science.1208344
2. Avoid sugars and processed carbs. Firmicutes love sugar. They’re even known to grow rampantly in factories that convert sugar cane to table sugar.³Sharmin, F., Wakelin, S., Huygens, F. et al. Firmicutes dominate the bacterial taxa within sugar-cane processing plants. Sci Rep. 2013;3:3107. https://doi.org/10.1038/srep03107
3. Have more beans. Eating beans is one of the best ways to boost Bacteroidetes.⁴Maslowski KM, Mackay CR. Diet, gut microbiota and immune responses. Nat Immunol. 2011;12(1):5-9. https://doi.org/10.1038/ni0111-5 But many people have trouble digesting them (a surefire sign of too few Bacteroidetes). Don’t avoid them completely! Studies show that slowly incorporating beans into your diet helps ease symptoms. Start slow, with one tablespoon of pinto beans daily at dinner. After two weeks, most people can tolerate more.⁵Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutr J. 2011;10:128. Published 2011 Nov 21. https://doi.org/10.1186/1475-2891-10-128
4. Sleep and eat on a regular schedule. Plenty of data⁶Thaiss CA, Zeevi D, Levy M, et al. Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis. Cell. 2014;159(3):514-529. https://doi.org/10.1016/j.cell.2014.09.048 show that intestinal bacteria follow a rhythm that changes throughout the day, just like our sleep–wake cycle. Shift work, jet lag, and irregular meal times can damage beneficial bacteria.

Weight management that embraces ‘balance’

Good health and weight management don’t require deprivation or pushing your body to its limits. It’s more about sustainability than struggle, nurturing a steady rhythm that supports physical and mental wellness.

Healthy weight management is rooted in balance: nourishing food, movement that energizes, and rest that restores. The journey toward a leaner, more energized body starts with cultivating a trusting partnership with your body.

Footnotes

• 1
  Durack J, Lynch SV. The gut microbiome: relationships with disease and opportunities for therapy. J Exp Med. 2019 Jan 7;216(1):20-40. https://doi.org/10.1084/jem.20180448
• 2
  Wu GD, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA, Bewtra M, Knights D, Walters WA, Knight R, Sinha R, Gilroy E, Gupta K, Baldassano R, Nessel L, Li H, Bushman FD, Lewis JD. Linking long-term dietary patterns with gut microbial enterotypes. Science. 2011 Oct 7;334(6052):105-8. https://doi.org/10.1126/science.1208344
• 3
  Sharmin, F., Wakelin, S., Huygens, F. et al. Firmicutes dominate the bacterial taxa within sugar-cane processing plants. Sci Rep. 2013;3:3107. https://doi.org/10.1038/srep03107
• 4
  Maslowski KM, Mackay CR. Diet, gut microbiota and immune responses. Nat Immunol. 2011;12(1):5-9. https://doi.org/10.1038/ni0111-5
• 5
  Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutr J. 2011;10:128. Published 2011 Nov 21. https://doi.org/10.1186/1475-2891-10-128
• 6
  Thaiss CA, Zeevi D, Levy M, et al. Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis. Cell. 2014;159(3):514-529. https://doi.org/10.1016/j.cell.2014.09.048