Overweight: Is Your Gut Bacteria Keeping You Obese

Overweight: Is Your Gut Bacteria Keeping You Obese

Overeating may not be the fundamental reason why someone is overweight

At the Washington University Medical School (St. Louis) in 2006, Jeffrey Gordon and his colleagues discovered that thin mice and obese mice had different populations of gut bacteria.  Through their experimentation they demonstrated that one particular type of bacteria can actually cause obesity.

OverweightIn one experiment they took baby mice that had been raised in a sterile environment so that their bodies would be free of any bacteria. Then they populated their guts with intestinal microbes collected from obese women and their lean twin sisters. The mice that had received the microbes from the obese twins, fattened up within 5 weeks. They gained 15 – 17% more weight even though both types were fed the same diet.

The culprits were identified as Firmicutes bacteria and all humans harbour them. And just like the mice, those of us who coexist with Firmicutes as part of our ecosystem are more likely to be overweight. Firmicutes can digest complex sugars that neither our own enzymes nor Bacteroidetes can. They break them into simple sugars and fatty acids that our intestines absorb more easily. Humans harbour bacteria from these same two lineages. With the overweight among us having more Firmicutes and fewer Bacteroidetes than slim people. This is exactly the same as in the fat and thin mice. Find out more from Jeffrey Gordon. Read more about the study using human twins and mice in the Journal Nature

Another study concentrated on the fact that each bacteria in our gut has a preferred food. Scientists Joe Alcock, Carlo C. Maley, and C. Athena Aktipis of the University of California San Francisco, suggests that bacteria can manipulate our brain into believing we need to eat a certain food. It sounds like science fiction, but it seems that bacteria within us may very well be affecting both our cravings and moods to get us to eat what they want. So are the bacteria driving us toward obesity? An article published in the September issue of BioEssays,  reviewed the research on how microbiota affect the brain, and believe there’s a strong case that bacteria can influence overall eating behaviour.

It seems that the bacteria in our guts don’t simply wait for whatever leftovers we have to offer. They actively seek out their preferred meals through hijacking our host’s nervous system. However, its not all one sided. To quote the article, “Because microbiota are easily manipulatable by prebiotics, probiotics, antibiotics, fecal transplants, and dietary changes, altering our microbiota offers a tractable approach to otherwise intractable problems of obesity and unhealthy eating.”

Question is, can we change the composition of our gut bacteria? Another researcher in the field of gut nutrition and microbes is Dr. Patrice Cani, a professor at Catholic University in Louvain, Belgium. In his lab he tracked the interaction between gut bacteria, metabolism and obesity. He discovered that when overweight mice were given a prebiotic, the number of mucin-degrading bacteria called Akkermansia muciniphila increased markedly. As a result, the mice lost almost half their body fat without any change in diet. Here is a link to an interview with prof. Patrice Cani about prebiotics.


So the answer seems to be that we need to balance our gut flora and the best way to do that is eat lots of healthy fibre. All plant foods contain fibre of which a certain amount cannot be digested in the small intestine and ends up in the large bowel (colon). Once it reaches the large bowel, the fibre is broken down for the good bugs as food and then its turned into calories for us. We need to eat a variety of fibre in the form of fruits, vegetables, beans and whole grains. The various types of bacteria need different types of fibre for healthy bacterial growth.



Feeding gut bacteria (the good guys)

Eating liberal amounts of the following foods provides your gut flora with the preferred fibre.

  • Chicory root
  • Dandelion greens
  • Garlic
  • Ginger
  • Jerusalem Artichoke
  • Jicama (Mexican yam)
  • Leeks
  • Parsnip
  • Potato
  • Radish
  • Rutabaga
  • Sweet potato
  • Taro (Root vegetable also grown for its ornate leaves)
  • Yams

This list is not exhaustive and there will be other vegetables that are suitable for the purpose of populating the gut flora. A lot of these can be used on their own or in soups and stews for healthy slimming diet. The bottom line is that the less processed any food is and the more fibre it contains, the better it is for your gut flora and therefore for you. Balance is the name of the game.

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