Are Antibiotics Fattening Us Up?
When penicillin was discovered, it was the answer to a prayer. From a world where we could literally die from a paper cut if it got infected, we began our evolution to a society that can cure the Black Death with a handful of pills and wipe out tuberculosis with a few months' treatment.
And penicillin was just the beginning.
As the years went by, more antibiotics were discovered and new uses found for them. One of these was quite unexpected — farmers found that feeding antibiotics to meat animals made them put on weight at an amazing rate. Since livestock sells by the pound, this meant that farmers could raise animals to market size on half as much feed and in half as much time. This in turn meant their profits went way up.
Soon everyone was feeding antibiotics to their animals. By 2015, 34 million pounds — an incredible four-fifths of all the antibiotics in the country — were used in animals, mainly to promote weight gain. Why is that important? For one thing, it's a big contributor to the problem of "superbugs" — bacteria which are immune to all known antibiotics. For another, it looks like agricultural antibiotics are making us fat too.
Why did no one consider this before?
We like to pretend that we're not animals, but the fact is that we are. We may be smarter. We may be more self-aware. We may write symphonies and operas and the Great American Novel. But on a biological level, we're still just animals. And logically, if antibiotics make all the other animals who eat them gain weight, it stands to reason that they'll make us gain weight too. But in spite of all the hand-wringing about our "obesity epidemic," somehow this simple idea has been ignored. In the rush to cure everything under the sun with antibiotics, the idea that they might fatten us up too got lost in the shuffle.
Or maybe it didn't.
Back in the 40s and 50s, when antibiotics first came into use, being underweight was more of a problem than being overweight, especially in kids. Scientists actually studied using antibiotics to help children gain weight. And it worked. Kids who were given low doses of antibiotics gained about 5 pounds per year more than kids who weren't. And when they tested the idea in adults, they found that those using antibiotics gained significantly more weight too.
Meanwhile, farmers discovered that animals eating a steady diet of antibiotics could live in even the filthiest conditions, and the factory farm was born. This led to even heavier antibiotic use and widespread pollution with farm waste. The situation continued to spiral out of control.
And we started to get fatter.
Not surprisingly, our ballooning weight went hand-in-hand with the increase in antibiotic use.
Give us this day our daily…drugs
From the early days, antibiotics were handed out like Halloween candy. Even today, as we stare at a future where all bacteria may become antibiotic-resistant and you can once again die from a paper cut, antibiotics are still over-prescribed. They're handed to pushy parents who just can't believe their kid has a viral infection that antibiotics won't help. They're given "just in case" in a variety of medical situations. And even if you've never had a prescription for antibiotics in your life, you're still getting a daily dose.
Thirty-four million pounds is an awful lot of antibiotics — and the bulk of them pass on through the animals who eat them, unchanged, to end up in manure. From there they make it into the water supply through the runoff from factory farms. Antibiotic-tainted water irrigates our crops. Factory-farm manure is used as fertilizer. So even our produce is sometimes laden with antibiotics. And of course factory-farmed meat is tainted too.
It took decades for anyone to listen when scientists warned that agricultural antibiotics were creating superbugs and Big Ag still refuses to cut back on their use. So imagine the backlash against scientists who link our increasing weight to antibiotics.
But the connection is there.
Studies have shown that children who get antibiotics before they're six months old are more likely to be overweight later. And just in case fifty years' worth of agricultural data isn't enough information, studies in mice have consistently found that those given antibiotics get fatter. There's no doubt it's a factor.
Now we think we know why.
Gut bacteria: your "invisible organ"
Antibiotics change the numbers and types of bacteria in our guts. Gut bacteria, we've learned, have a huge amount of influence on our health, from our immune systems to our brains. We need the right mix of different types of bugs or we get sick. And if we have too many of the wrong type, we also get fat.
This isn't wild speculation. Research has shown that taking the gut bacteria of fat mice and transferring them to skinny mice makes the skinny mice get fat. Likewise, putting "skinny" bugs in fat mice makes them drop the weight.
Antibiotics changes the balance of the bugs in our guts, letting the fat-promoting ones multiply unchecked. And once that bacterial population gets out of control it's incredibly hard to get our bodies back in balance.
Tips for avoiding antibiotics
Food is a source of hidden antibiotics. Milk, for example, can legally contain up to 100 micrograms of tetracycline — an antibiotic commonly used both in animals and in people — per kilogram. Antibiotics have been found in carrots and lettuce. There are limits on how much can be present in meat, but it's still there. This makes buying organic, and sticking to the "antibiotic-free" label a good first step.
Nearly every water source we have is polluted with agricultural waste to some degree, and most bottled water isn't any safer. However a high-quality reverse-osmosis water filter can remove antibiotic residue, and many other contaminants besides.
Antibiotics change our guts by killing off the "good" bacteria that live there, so replacing them is incredibly important. Adding fermented foods like yogurt, kefir, sauerkraut, and kimchi to our diets helps re-populate our guts with beneficial bacteria and keep the "bad" ones in check.
We're still learning about gut bacteria. We now know that they influence our weight, our metabolism, our immune systems and more. Antibiotics disturb the balance, and avoiding them is important. So buy organic. Buy local. Filter your water. And the next time your doctor offers you a prescription for antibiotics, ask if they're really medically necessary.