These Little Bugs Decide If You Get Fat

Guest post written by: Dr. Amy Shah


Those little critters that live deep in your bowels — i.e. gut microbiota — are all the rage in medicine right now.

In fact, fecal transplants (yes, it is what it sounds like) have been PROVEN to cure certain diseases that antibiotics can’t even touch.

But recently there has been some even more interesting research that shows that the type and amount of bacteria we have in our gut can make us overweight or lean.

For example, a 2006 study in the journal Nature found that obese people all have a classic imbalance in gut bacteria when compared with lean people — even when they controlled for all the other differences in these people’s habits.

Another study published in 2013 in the journal Cell found that being lean is associated with having more Christensenellaceae bacteria in your gut while having less is associated with gaining weight.

In both these studies, when the overweight individuals changed their diet — they also changed their gut bacteria to match the lean population — and then were able to lose the weight.

Cool, right?

Yes, I know all these drug companies are going to run to every “doctor” TV show and say — just by “eating this new Christensenellaceae pill” you can get thin.

But wait, is it that simple?

Of course not.

Other studies show that it not just ONE type of bacteria we need to be lean — overweight people have less gut microbe diversity whereas lean people have tons of different types of gut bacteria.

Several studies also tell us the more diverse your gut bacteria, the less likely you are to be obese or have type 2 diabetes.

Another study came to a similar conclusion.

Less gut microbe diversity is associated with holding onto more fat, being insulin resistant and generating more inflammation — all of which contribute to weight gain.

Wait — so what’s my point?

The bottom line is you want to work on getting your gut lots of the “good” bacteria and also give it a lot of diversity (think lush forest vs barren desert)

Which foods/habits have specifically been shown to modulate the little critters?

1. Fermented foods: Kimchi, fermented vegetables etc.

2. Fiber: Getting fiber from things like vegetables feeds good bacteria.

3. Outdoor Exercise: A 2013 study in the journal Gut among Irish rugby players found that exercise is associated with more gut bacteria diversity. The study also found lots of a bacteria associated with lower weight among the players. It probably also helps that they are rolling around, punching each other in dirt — which is full of bacteria.

4. Lots and Lots of Vegetables

But what about probiotics???

In a study, overweight women who took probiotics for 12 weeks lost weight — and kept it off — compared to women who took a placebo. But this has not played out in all studies.

Most probiotic pills don’t survive our complex digestion process to stay intact all the way to the intestines. You are better off, in my opinion, eating a really clean diet with tons of vegetables and cutting out processed foods.

Now, we do know some things can totally wipe out good gut bacteria:

1. Sugar (didn’t see that one coming did you?)

2. Processed fats/oils

3. Processed snacks/grains

4. Antibiotics

5. Over sanitizing (hand sanitizer, Neosporin for small cuts, antibacterial soaps)

I’m pretty excited about this topic as I think it offers a powerful way to frame our interactions with the modern world using this Ancestral Health model.

Eat (things that were once) dirty, play dirty, think dirty (kidding about that last one).


Want a one week guide to lower your inflammation (gut and otherwise)? If so -check out this free infographic!


Amy Shah MD is a double board certified physician trained in Internal Medicine and Immunology/Allergy.
With her background in Nutrition from Cornell University and her Medical Residency Training at Harvard and Columbia Hospitals– she has a strong western medicine background but an integrative approach to health.
She pursues her passion to blend the two and get optimal health at

Original Source: These Little Bugs Decide If You Get Fat


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