SIBO and Weight Gain

I gain weight very easily.

It seems I’ve been on a diet all of my life, and to some extent I’ve likely messed up my metabolism quite badly. I have to eat very low calorie and maintain and exercise regime to keep my body at the weight and shape I prefer.

Essentially, I’m fighting my set point. And its hard. But it’s a choice I’ve made.

With SIBO, though, it seems like I have to try even harder to keep my weight down. And when I do slip up and eat more than usual, my body stores it as fat immediately.

And now, I’ve come across some research that may explain what’s going on with that.

There are two types of organisms that are predominant in SIBO- hydrogen producing bacteria and methanogenic producing archaea.

And a study on nearly 800 subjects published in 2013 found that subjects who tested positive for both elevated hydrogen and methane levels had a significantly higher BMI than subjects who tested positive for hydrogen or methane alone. I have both hydrogen and methane producing organisms in my SIBO.

In a previous study by the same researchers, they found that subjects who were methane-producers had a higher BMI than people who were not methane producers (hydrogen was not tested).

And finally, a animal study demonstrated that when germ-free mice were colonized with a particular strain of methanogenic archaea called Methanobrevibacter smithii, they gained more weight than other mice.

M. smithii is the most abundant methanogenic archaea in the human GI tract, and appears to be the predominant species in methane-positive SIBO.

The researchers hypothesize the reason for the increased weight in humans may be due to this:

M. smithii feeds on hydrogen gas to produce methane.

Normally, hydrogen bacteria are self limiting. Once they create a particular amount of hydrogen gas, they get a signal to stop eating.

But if M. smithii is there eating up the hydrogen gas, the hydrogen-producing bacteria continue to ferment food and produce more hydrogen.

But that’s not all they do.

Hydrogen bacteria also synthesize short-chain fatty acids that you (the host) use as fuel, and they also make calories more available.

In essence, they help you get the most calories from what you eat.

So someone without SIBO may only absorb 75% of the calories from a particular food, but a person with SIBO may absorb 90%, and therefore need to consume less food overall to maintain caloric balance.

This hypothesis isn’t proven, and it’s likely there are more factors involved such as hormone dysregulation and metabolism dysregulation.

But it’s an interesting idea and it seems to make sense based on my experience.

So its at least good to know my struggle to keep my weight down since getting SIBO isn’t all in my head. And there are a number of folks out there that sees to have weight issues with SIBO as well.


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