Are Antibiotics Making You Fat?

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You have probably heard about antibiotics being present in cow’ milk and meat. That is because antibiotics help them gain weight, as it was discovered back in the 1940’s, but the reason for this wasn’t quite clear. Nevertheless, farmers started giving drugs to cows in small doses, and it quickly became a normal thing, leading to almost 90 percent of all antibiotics on the U.S. market being sold to be used on cows.

This fattening effect can similarly happen to humans as well.

A study conducted by researchers from New York University published in Nature, in August 2013, showed that mice that were given small doses of antibiotics gained 10-15% more fat over the course of seven weeks. This is because the microbes present in the gut are able to process some carbohydrates that the body is unable to do without them, and antibiotics enhance the power of those microbes to do so, which eventually leads to converting those carbs into body fat.

Seeing this, the same team of researchers conducted a study on humans in the 1990s, particularly kids taking antibiotics, in order to see if it will have the same effect on children.

Over 11,000 children participated in the study, and around 3,660 kids were given antibiotics before they were six months old. The study results showed that the chance of becoming overweight by the age of three for those children was 22% higher than for those who didn’t take antibiotics. However, by the age of seven, this effect was no longer in power, so the consequences are not entirely permanent.


But even if you don’t take antibiotics in the form of a pill, you are still eating animal meat that is packed with antibiotics.

Even if those are small amounts, according to a study published in the American Society for Microbiology, they can disrupt the balance between the good and harmful microbes in your gut and they are strong enough to destroy what’s useful for digestion, while not strong enough to kill pathogens such as E. coli.

A microbe researcher from New York, Martin Blaser, reviewed a study from 2010 and suggested that the use of antibiotics permanently changes our gut flora, and on top of that it increases the risk of becoming obese.

Blaser conducted his own research in which he included 92 U.S. veterans, of whom 38 had no H. pylori, 44 did and 10 were indeterminate. Twenty-three veterans who were positive to H. pylori were given antibiotics, and the drug didn’t cure it in only two of them. Those 21 veterans whose H. pylori was destroyed turned out to gain a lot of weight, and their BMI raised by 5%. The other 2 whose H. pylori was unsuccessfully treated didn’t gain any weight.

Now this becomes very scary when we think about all the food packed with antibiotics.

We are basically being given drugs without even being aware of it. But don’t despair – you can buy your meat and milk from a trusted farmer who takes care of his livestock and doesn’t feed it hormones and antibiotics. Grass fed meat is your best choice. As for prescription antibiotics, don’t reach for them every time you feel a little off, but resort to them only when you absolutely need to.

Weight gain is not the only issue, other effects such as indigestion, eradication of good bacteria and such are equally dangerous. And not to mention that weight gain can lead to obesity and diabetes, and even cancer in extreme cases, so this is not to be taken lightly.