How Microplastics Might Be Messing With Your Weight

Bottled water is a major source of microplastics.
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You'd never try to eat the plastic wrap on the outside of your sandwich or the plastic bottle that holds your water or iced tea. But it turns out that you might be consuming some of those plastics anyway. And they could potentially be affecting the number you see when you step on the scale.


Meet microplastics: miniscule plastic bits that make their way into our bodies via the foods we eat and the drinks we sip. The average U.S. adult unknowingly consumes an average of 70,000 microplastic bits per year, according to a June 2019 analysis published in the journal Environmental Science & Technology. And the science suggests that the chemicals in these pint-sized pieces have the potential to mess with your health — and your weight.

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Here's what you should know, plus the simple steps you can take to reduce your consumption.

What Are Microplastics, Exactly?

Microplastics are teeny, tiny plastic particles or fragments that occur in the environment as the result of pollution. (Some are microscopic, but they can be as large as a sesame seed, according to the National Ocean Service.)

Microplastics can be broken-off fragments of bigger plastic-containing items like packaging, plastic bags or polyester fibers that aren't disposed of correctly — like a plastic food container left on the beach. Microplastic granules can get sloughed off from items that are used in the water, like plastic buoys or floats, too. They can even come from scrubby cleansers, exfoliators or other cosmetics that get washed down the sink.


Experts don't know for sure how much microplastic material is out there, but they know it's a lot. Researchers have estimated that there's somewhere in the neighborhood of 270,000 tons of plastic particles floating at the top of the ocean, and it's impossible to say how much more is beneath the surface, according to a December 2014 article in PLoS One.

Regardless of the exact amount, there's enough out there for marine life to be gobbling the stuff up in abundance, which is one way they enter our food supple. And since wastewater plants can't filter every microplastic particle out of the water supply, it can end up in the H20 that we drink, too.


Read more: How Many Bottles of Water Should You Drink in a Day?

"It's clear that the plastic waste we are creating is now being incorporated into our food."

Are Microplastics Making You Fat?

You might already be familiar with some of the ways that the chemicals found in plastics can impact our health, but here's a quick refresher: "Plastics contain a mix of additives like bisphenol-A, phthalates, and nonylphenol, which might cause endocrine disruption," explains Subhankar Chatterjee, PhD, an environmental scientist at the Central University of Himachal Pradesh in India who studies microplastics. Endocrine disruptors can mimic hormones that the body already makes and potentially modify how those hormones normally function, according to the National Institute of Environmental Health Sciences.



This hormone unbalance could set the stage for serious health problems like heart disease, according to an August 2014 study published in the International Journal of Environmental Research and Public Health. And some research has also linked it to infertility in women, including a July 2016 review in the journal Fertility and Sterility.

Endocrine disruptors in microplastics seem to have the potential to up your risk for obesity, too. A growing body of evidence, laid out in a February 2017 review in Current Obesity Reports, shows that the chemicals can interfere with weight in a number of ways, including increasing the body's number of fat cells, boosting the size of fat cells, messing with hormones that regulate hunger and satiety, altering insulin sensitivity, slowing metabolism and encouraging the body to store more calories.


Read more: 7 Unexpected Reasons Why You're Not Losing Weight

Microplastics might also have an impact on obesity risk by messing with the bacteria in the gut, aka the microbiome. At least, that's what research on mice, published in the August 2018 issue of Science of the Total Environment, seems to suggest. "Mice aren't humans, but we do know that when the microbiome is disrupted in humans it leads to many diseases, including type 2 diabetes and obesity," Erin Pitkethly, RPh, a registered pharmacist and certified nutritionist with Robinsong Health in Ontario, Canada, tells


Is the evidence strong enough to pin all of our weight struggles on microplastics? Nope — far from it. Chatterjee says the particles could play a role in the current obesity crisis, but points out that more studies are needed to know for sure. Still, considering what we do know about plastic chemicals' effects on health, steering clear when you can probably isn't a bad idea. "Although this research is in its infancy, we would all do well to take notice and minimize exposure to these substances," says Pitkethly.


"On average, switching from bottled to tap water would reduce your microplastic consumption by over 100,000 particles per year."


How We’re Consuming Microplastics

Even though you're not seeing or tasting them, chances are you're ingesting a lot more microplastics than you think.

For the June 2019 analysis in Environmental Science & Technology, researchers reviewed 26 studies to determine the amount of microplastics in some common foods and drinks like fish, shellfish, added sugars, salts, alcohol and tap and bottled water. Then they assessed how much of these foods Americans consume based on current dietary recommendations to estimate the amount of microplastics most of us are eating. The number? A staggering 74,000 to 121,000 particles per year. And those numbers could actually be on the low side, since the experts only looked at 15 percent of Americans' total caloric intake.

The analysis examined foods and drinks that have already been found to contain microplastics: Bottled water was a major source of exposure, perhaps because microplastics from the bottles get sloughed off into the water. Fish and shellfish were also biggies, since marine life can consume microplastic bits in the ocean.

Read more: Which Fish Has the Highest and Lowest Mercury Levels

As for the rest of the food pyramid? It's possible that other foods or drinks could serve up a side of microplastics too. But experts haven't yet looked at the microplastic concentration in most of the things we eat, including meat, poultry, dairy, grains, fruits and vegetables.

How to Avoid More Microplastics

Will minimizing your microplastic intake make it easier to lose weight or improve your health in other ways? For now, we don't have a definite answer. But if the idea of eating tiny bits of plastic just doesn't sit well with you, you might still be wondering what you can do to curb your consumption.


There's not currently enough evidence for experts to issue recommendations to limit or avoid certain foods. But you can keep more plastic chemicals out of your food by avoiding plastic packaging or plastic bags whenever possible, Kieran Cox, PhD candidate at the University of Victoria and co-author of the June 2019 analysis, tells "It seems to be the case that food items closely associated with plastic will result in more plastic consumption," he says.

So try storing foods in glass containers or wrapped in wax or parchment paper instead. And limit your use of bottled water. "We can say that, on average, switching from bottled to tap water would reduce your microplastic consumption by over 100,000 particles per year," says Cox.

As for seafood? Studies show that fish and shellfish are, in fact, sources of microplastics in our diets. But that's not reason to cut them out of your diet, Cox warns. For starters, seafood still serves up a number of valuable health benefits. And since there's no data on microplastics in other protein sources, experts don't know how the amount of microplastics in seafood might stack up to other foods like beef or chicken. (It could be that beef or poultry, for instance, harbor just as many microplastics as salmon.)

Finally, find ways to reduce your use of plastic overall. For example, use reusable shopping bags, seek out products packaged in paper or cardboard instead of plastic and skip those plastic produce bags at the grocery store. "It's clear that the plastic waste we are creating is now being incorporated into our food," says Cox. "So reducing plastic waste in general has the potential to reduce our consumption of plastics."