“Antibiotics Make You Fat”: A Chance for Readers to Weigh In
Updated at 1369415947

 That got your attention.  It isn’t true—or, at least we don’t know if it’s true.  Antibiotics probably don’t make you fat. But stay with me.  A study published in Science Translational Medicine reports that the weight loss after a particular type of bariatric surgery (that’s surgery to remodel the stomach and intestine) called Roux-en-Y is only partially accounted for by the remodeling itself.  Some non-trivial amount is due to replacement of the intestinal bacterial flora with a different mix of bacteria that are “skinny bacteria,” as opposed to the “fat bacteria” that populated the same areas pre-surgery.

The experiment involved bacteria-free fat mice, which were given post-surgery flora from mice that had undergone Roux-en-Y bariatric surgery.  The mice with the replaced flora but without surgery lost significant amounts of weight.

So you see where I’m going with this.  The most direct translation (if the finding holds true in humans) is that overweight people can be “transfused” with bacteria from skinny people  But suppose we could show that it’s the skinny bacteria whose numbers decline more after an antibiotic course than fat bacteria.  Then we could tell people that antibiotics are making them (and their children) fat, and that they shouldn’t take antibiotics when they don’t need them, e.g., for the common cold and most other upper respiratory coughs and sniffles. 

What I’m getting at is that we need incentives to stop the overuse of antibiotics.  If the consequences were as direct as getting fat—or at least perceived as such—motivating people to change their behavior would be a snap.  There are real consequences to antibiotic use, but for the most part they accrue to society and posterity.  They aren’t immediate and they aren’t to the individual.  Sure, some people have allergic reactions, some serious.  And people can catch antibiotic resistant infections -   everyone’s read a news story about a victim of MRSA (methicillin-resistance Staphylococcus aureus) even if they don’t know one personally - but it hasn’t happened to most.

If we could honestly say that taking antibiotics contributes to obesity it might have the effect of dissuading people from taking them even when they’re needed, and that wouldn’t be good.  But it would certainly cut down on using them when not needed—or “just in case.”  The point is that we don’t currently have convincing arguments that would allow the right balance to be struck:  antibiotics when needed and not when clearly not needed.

Back to you, dear reader.  Your turn to propose an idea: what message do you think could stop people from overusing antibiotics?  And of course, the message has to be true. We can’t lie - antibiotics probably don’t make you fat.