Gut bacteria driving obesity?

do gut bacteria drive obesity?

Here’s a new study that might have you loading your grocery cart with yoghurt: gut bacteria differs between obese and thin people.  Actually, this isn’t news; several studies reported on this phenomenon last year alone.  This new study looked at the genetic behavior of intestinal bacteria from lean and obese subjects, as well as people with inflammatory bowel disease.  I admit, some of the wording in this report is beyond me:

… obese microbiomes are less modular, a hallmark of adaptation to low-diversity environments. We additionally link these topological variations to community species composition…

Or: obese people have different gut bacteria from lean people.  And those obese bacteria are able to metabolize more calories out of the food being digested.  Obese people everywhere may be feeling vindicated; they knew something was different.  But it’s not so much their metabolism, as the metabolism of the bacteria living in their intestines.  Here’s a weird possibility: the bacteria in obese people are “hungry” and actually send out their own hormone signals to drive eating.  Sounds something like a space alien invasion movie.  Well, gut bacteria cells are thought to outnumber the cells in our bodies by 10 to 1.  That’s a whole lot of hungry little cells.

What to do?  So far there’s no evidence that deliberately changing the bacteria, by eating probiotic food, will change calorie absorption.  Eating yoghurt won’t cause magic weight loss.  Here are some of the possible scenarios:

  1. A lifestyle and diet that causes obesity leads to different “obese” gut bacteria.  This explanation is actually hinted at in another study, which showed that when obese people lost weight, their resident bacterial population became more like that of lean people.  Diet => obesity => bacteria.
  2. Some people have different bacteria, and as a result they gain weight easily and become obese.  Bacteria => obesity.  If this is true, simply changing the bacteria by eating probiotic foods could fix obesity.
  3. Bad diet changes gut bacteria to the type that makes weight gain easier.  Diet => bacteria => obesity.  Eating a healthier diet would help change the bacteria and help with weight loss.

So far, #1 is the more likely scenario.  Which means merely changing gut bacteria will not fix obesity.  If you’re obese, you can assume you fit the pattern of gut microbes common to obese people.  Losing weight is likely to change the bacteria, although whether this is caused by the weight loss or the improved diet food choices isn’t clear.  Adding yoghurt to your diet might help with dieting efforts, although it’s not likely to result in miracle weight loss.  If you do that, please eat real yoghurt, not faux yoghurt gunked up with sugar syrups, artificial sweeteners and thickeners.

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