Are Antibiotics Making Us Fat?

Farmers have long used antibiotics to fatten up livestock—and now there’s growing evidence that these drugs may have the same effect on people.  What’s more, instead of being miracle cures, there’s now scary speculation that antibiotics could be jeopardizing our health by making us more prone to lifestyle diseases, from type 2 diabetes to heart attacks and fatal strokes. If that sounds far-fetched, consider this: States with the highest rates of antibiotic prescriptions also rank as the least healthy, Wired magazine reported on November 25.

When the nonprofit research group Extending the Cure recently mapped antibiotic prescriptions by state, it found the heaviest use (measured per 1,000 people) in the eastern half of the US, particularly West Virginia, Kentucky, Tennessee, Louisiana, and Alabama, all of which comprise the so-called Stroke Belt, due to the high rate of stroke fatalities. According to CDC data, Wired adds, these states (and to a lesser extent, much of the eastern US) also have higher rates of obesity, diabetes, and heart attacks, compared to the western US. While these correlations don’t prove that antibiotic overuse triggers these diseases, studies suggest that it could drive up obesity by changing how our stomachs work. Here’s a look at the findings.

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First shown to cause weight gain in 1954.

More than a half century ago, a randomized study published in Nutrition reported that Navy recruits who were given daily doses of broad-spectrum antibiotics, such as chlortetracycline or penicillin, to prevent strep infections gained 4.8 pounds over 7 weeks, compared to a 2.7 pound gain in recruits given a placebo. 

Eradicating beneficial gut bacteria.

In the early 20^th century, helicobacter pylori was the dominant stomach microbe, Dr. Martin Blaser, a microbiologist professor at New York University Langone Medical Center, recently reported in Nature. Today, the average American child receives 10 to 20 courses of antibiotics by age 18, and fewer than 6 percent of US kids carry the organism. While that may not sound like a problem, given that H. pylori raises risk for stomach ulcers and gastric cancer, Dr. Blaser has discovered that killing off this bug dramatically changes how the stomach works, tricking the body into overeating. 

A six-fold rise in hunger hormones.

Normally, after a meal, levels of the hunger hormones ghrelin and leptin drop, signaling that we’re full. However, a 2011 study by Dr. Blaser and other scientists found that after veterans were treated with antibiotics to eradicate H. pylori, they had 20 percent rise in leptin levels after a meal, while levels of ghrelin skyrocketed six times higher. And 18 months after treatment, on average, participants had a 5 percent rise in their body mass index. That would be a 10-pound gain in someone with a starting weight of 200. 

NEXT: Antibiotics Linked to Other Diseases >>