- Overweight and obesity have seen a sharp rise in recent times.
- Researchers believe this is not solely driven by diet and physical inactivity.
- The latest research suggests chemicals in plastic products may be a contributing factor.
Overweight and obesity levels have been hitting record-high levels in the last few decades. Since 1975, worldwide obesity has nearly tripled, according to the World Health Organization (WHO).
These are shocking figures, especially when one considers that they are preventable. But the solution might not be as simple as eating more healthily and increasing physical activity. A new study proposes a theory that chemicals in everyday plastic products may be responsible for weight gain by changing human metabolism.
That’s right. The researchers found that a range of plastic household items (including soft drink bottles, refillable drinking bottles, bin liners, yoghurt containers, and freezer bags) contain chemicals that may alter human metabolism by promoting the growth of fat cells, known as adipocytes.
The authors wrote: “This public health problem has been largely attributed to genetic background and changes in lifestyle, such as diet, exercise, sleep deficiency, and ageing. However, epidemiological evidence suggests that these factors are not sufficient to explain the magnitude and speed of the obesity pandemic’s spread.”
They go on to say that studying other environmental factors than lifestyle is key to understanding and managing obesity.
Hints by earlier research
Previous research points to other factors influencing the increase in obesity. A study published in 2016 found that factors other than diet and physical activity may be behind the increase in BMI over time. But the authors could not point out exactly what they were, and simply noted that further research is necessary to identify these factors and mechanisms affecting body weight.
The current study may bring us one step closer toward understanding these factors. The findings appear in Environmental Science & Technology.
The endocrine system
The endocrine system regulates appetite, metabolism, and weight, among others. As a result, the researchers believe that exposure to endocrine-disruptors (synthetic chemicals in our environment) is one such factor that needs to be closely studied.
Bisphenol A (BPA) is a commonly known endocrine disruptor, which is manufactured in large quantities globally and can be found in some plastics. Phthalates is another, and can be found in hundreds of personal care products such as shampoos and soaps. Sometimes companies are not required to list them on products, as reported by The Guardian.
But thousands of chemicals can be found in plastic, many of which are unknown. Therefore, the biologists and authors of the current study, from the Norwegian University of Science and Technology in Trondheim, decided to dig deeper.
What they found
The team used methanol to extract chemicals from 34 everyday products. Their work incorporated a technique whereby they could identify both known and unknown substances.
More than 55 000 chemical features were identified, including 629 known substances, 11 of which disrupt metabolism.
Next, they examined the extracts from each of the products. The findings were surprising.
“It’s very likely that it is not the usual suspects, such as bisphenol A, causing these metabolic disturbances,” study author Dr Johannes Völker said in a news release.
He added: “This means that other plastic chemicals than the ones we already know could be contributing to overweight and obesity.”
Results not definitive
While our first thought might be to put the blame on food packaging, it might not be the only potential source capable of disrupting metabolism.
The substances may also travel into the body via the skin, such as inhaling dust that contains chemical mixtures after being in contact with plastic flooring.
The authors wrote: “Given the potency of the extracted mixtures and considering our close and constant contact with plastics, our results support the idea that plastic chemicals can contribute to an obesogenic environment and, thus, the obesity pandemic.”
However, because the study is based on cells grown in dishes in a lab setting, as opposed to animals, the researchers pointed out that their results are not definitive and future research is needed to support this.
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