Scientists reviewed studies on how certain chemicals found in everyday products affect how quickly our bodies burn energy. These chemicals, called endocrine disruptors, are found in things like pesticides, plastics, and flame retardants. The research shows that some of these chemicals may slow down our metabolism (the rate we burn calories), while others might speed it up. The effects were different for males and females, and they depended on what dose of the chemical someone was exposed to. Understanding how these chemicals affect our bodies could help explain why some people struggle with weight gain and metabolic problems.

The Quick Take

  • What they studied: How chemicals that disrupt our hormones affect the rate at which our bodies burn calories and energy
  • Who participated: This review analyzed 12 animal studies (mostly using mice) and 9 laboratory studies using cells. The research looked at exposure to various chemicals including pesticides, plastics, and flame retardants
  • Key finding: Different chemicals had different effects: some chemicals like DDT and certain flame retardants slowed down calorie burning, while others like some plant-based chemicals actually increased it. The effects varied between males and females
  • What it means for you: This suggests that exposure to certain everyday chemicals may contribute to weight gain and metabolic problems by affecting how efficiently our bodies burn calories. However, this research was done in mice and cells, so we need human studies to confirm these effects apply to people

The Research Details

This is a systematic review, which means scientists searched through published research and carefully selected studies that met specific quality standards. They looked at 12 animal studies (conducted in mice) that examined how different chemicals affected energy expenditure—basically how many calories the body burns at rest and during activity. They also reviewed 9 laboratory studies using isolated cells to understand how these chemicals damage mitochondria, which are the tiny structures inside our cells that produce energy.

The researchers examined exposure to many different chemicals including DDT (an old pesticide), bisphenol A (BPA, found in some plastics), phthalates (used to make plastics flexible), and flame retardants added to furniture and clothing. Some studies looked at single chemicals, while others examined mixtures of multiple chemicals that people might encounter together in the real world.

By combining results from multiple studies, the researchers could identify patterns in how these chemicals affect our metabolism and energy production at the cellular level.

A systematic review is valuable because it combines evidence from many studies rather than relying on just one experiment. This approach helps scientists see the bigger picture and identify consistent patterns. Understanding how chemicals affect our metabolism is important because it could explain why exposure to certain pollutants is linked to obesity and metabolic disease. If we know which chemicals slow down calorie burning, we can better protect people from exposure and develop strategies to prevent weight gain.

This review included only published studies that met specific quality criteria, which strengthens the findings. However, all the studies reviewed were conducted in mice or cells, not humans. The effects of chemicals on mice don’t always match what happens in people. Additionally, the review found that effects varied significantly depending on the dose of chemical, the sex of the animal, and the diet they consumed, which means the real-world impact is complex and may differ from person to person

What the Results Show

The research revealed that different chemicals affect how our bodies burn calories in different ways. Some chemicals, including DDT (a pesticide), tolylfluanid (a fungicide), benzene (found in gasoline), and certain flame retardants, actually decreased the rate at which bodies burned calories. This slowdown in calorie burning could contribute to weight gain over time.

Other chemicals, including bisphenol A and bisphenol S (chemicals used in plastics), and butyl-phthalate (used to make plastics flexible), had a neutral effect—they didn’t significantly change calorie burning. Interestingly, some chemicals like certain plant-based compounds and deltamethrin (an insecticide) actually increased calorie burning.

At the cellular level, the research showed that several chemicals damaged mitochondria—the energy-producing structures in our cells. This damage was found in muscle cells, fat cells, and liver cells. When mitochondria don’t work properly, cells can’t produce energy efficiently, which could slow down overall metabolism.

The effects weren’t the same for everyone: males and females sometimes responded differently to the same chemical, and the impact depended on how much chemical someone was exposed to and what they ate.

The review found that the effects of these chemicals often depended on diet. Some chemicals had stronger effects when animals ate a high-fat diet compared to a normal diet. This suggests that chemical exposure and poor diet might work together to cause metabolic problems. Additionally, the timing and duration of exposure mattered—some effects appeared only with long-term exposure, while others showed up with short-term exposure. The research also showed that some chemicals affected males and females very differently, suggesting that sex hormones play a role in how these chemicals impact metabolism.

Previous research had shown that these chemicals increase the risk of obesity and metabolic disease, but scientists weren’t sure exactly how. This review helps fill that gap by showing that one important mechanism is through effects on energy expenditure and mitochondrial function. The findings support the idea that these chemicals don’t just make people eat more—they also change how efficiently their bodies burn calories. This adds to growing evidence that environmental chemical exposure is a significant but often overlooked factor in the obesity epidemic.

The biggest limitation is that all studies reviewed were conducted in mice or cells, not humans. Mice metabolism works differently from human metabolism, and results in cells don’t always translate to what happens in whole living bodies. The review also found huge variation in how studies were conducted—different doses, different exposure lengths, different types of chemicals—which makes it harder to draw firm conclusions. Additionally, most studies looked at single chemicals in isolation, but in real life, people are exposed to many chemicals at once, and we don’t fully understand how mixtures interact. Finally, the review couldn’t determine cause and effect in humans because human studies are mostly observational (watching what happens) rather than experimental

The Bottom Line

Based on this research, it’s reasonable to try to reduce exposure to these chemicals where possible (moderate confidence). This includes choosing products without BPA and phthalates, reducing pesticide use, and improving ventilation to reduce exposure to benzene and other air pollutants. However, these findings are from animal and cell studies, so we should wait for human research before making major life changes based solely on this information (low to moderate confidence). Maintaining a healthy diet and regular exercise remain the most proven ways to manage weight and metabolism

This research is most relevant to people concerned about environmental health, those with metabolic disorders or obesity, pregnant women and children (who are more vulnerable to chemical exposure), and workers exposed to pesticides or industrial chemicals. People living near industrial areas or agricultural regions with heavy pesticide use should be particularly interested. However, the general public should also be aware because many of these chemicals are found in common household products. This research is less immediately relevant to people with no chemical exposure concerns, though everyone is exposed to some level of these chemicals in modern life

If these findings apply to humans, changes in metabolism from chemical exposure would likely develop gradually over months to years of exposure, not overnight. Similarly, if someone reduced their chemical exposure, it might take weeks to months to see improvements in metabolism. The effects would be most noticeable when combined with other healthy habits like exercise and good nutrition

Want to Apply This Research?

  • Track weekly calorie expenditure or activity level using the app’s fitness tracking feature, noting any changes over time. Also track exposure to potential sources of these chemicals (pesticide use, new plastic products, flame retardant-containing furniture) to see if reducing exposure correlates with changes in energy levels or weight
  • Use the app to set goals for reducing chemical exposure: choose BPA-free products, track pesticide use in your home and garden, and monitor your energy levels and metabolism markers. Log dietary changes and exercise to see how they interact with efforts to reduce chemical exposure
  • Over 3-6 months, track resting metabolic rate (if your app measures this), energy levels throughout the day, and weight changes while simultaneously reducing exposure to common endocrine disruptors. This personal tracking can help you see if chemical reduction affects your individual metabolism, even though the research is still preliminary

This research was conducted in mice and laboratory cells, not humans. While the findings are scientifically interesting, we cannot yet confirm that these effects occur in people or that they significantly contribute to weight gain in humans. This review should not be used as the sole basis for medical decisions. If you have concerns about chemical exposure or metabolic health, consult with a healthcare provider. This information is educational and does not replace professional medical advice. Always speak with a doctor before making significant changes to your diet, exercise, or lifestyle based on research findings.