It may not surprise you that the majority of my patients come in with some level of concern about their weight. Even if it is not their primary concern, the issue is on their short list. Certainly part of that comes down to societal constructs of what we think we should look like, comparing perfectly healthy bodies to an image that isn’t necessarily right for all. There are, however, many people who are considered overweight or obese and would like to lose weight and these numbers are on the rise.
For most people weight loss is incredibly challenging, even when they do have a healthy lifestyle. Many of these patients wonder if there is something else going on. Why do their bodies respond differently?
There are many nuances to nutrition, nutrient timing, exercise type and intensity that may affect one’s success with body composition goals, but there are also many other factors at play.
Metabolic abnormalities, total cortisol (the stress hormone) and its daily rhythm, the microbiome, genetic differences in how we respond to nutrients, sex hormone imbalances, inflammation, and more can play a part in determining your body weight. Another less commonly discussed factor is toxin exposure.
What is a Toxin?
Hearing the word “toxin” I can’t help but cringe. This term is abused by advertisers that tout products that have vague claims about ridding your body of unnamed toxins without really explaining which toxins they are referring to or how exactly their products work.
I whole-heartedly agree that we are excessively exposed to toxins and that limiting this exposure and supporting our bodies to process them is important, but I’d like to be more specific. In the following paragraphs I hope to put a name to a few of those toxins, inform you of how they can affect body composition, and give you real world examples of what to do about it.
There are numerous chemicals potentially involved here, some causing larger problems than others. A large systematic review of studies from 1995-2016 indeed showed a significant positive correlation between pollution exposure and obesity. This study looked at many chemicals, and showed that not all pollutants have the same level of effect on obesity risk, and they influence weight in different ways. Here are a few you should know about:
BPA (and other bisphenols)
One that is associated with higher risk for obesity is BPA. BPA stands for Bisphenol A and is found in plastic water bottles, lining aluminum cans, and even on receipts. Higher urinary BPA levels have been associated with greater risk for abdominal obesity, diabetes, and hypertension. (1) Be careful about trying to bypass this compound by buying “BPA-free” bottles however. There are other bisphenols in plastics that may be just as bad, if not worse, that BPA is replaced with.
Phthalates are another component of many plastics that correlate with obesity and insulin resistance. (2) Phthalates are also found in cosmetics, soaps, paint, lubricants, and pesticides. Like many other pollutants, phthalates are known endocrine disruptors. This means they influence hormones like testosterone and estrogen. Phthalates, for example, reduce testosterone contributing to obesity in men. There is even a term for these endocrine disrupting chemicals that cause obesity: obesogens.
Another major consideration is air pollution which can consist of many different chemicals. Several studies, often done in Los Angeles, describe the effects of air pollution on weight and blood sugar control. They found that even ambient air pollution can cause an increased risk of obesity and contribute to insulin resistance, a precursor to type 2 diabetes. (3) (4) (5)
In fact, simply living closer to a major roadway is associated with higher BMI, subcutaneous adipose tissue (fat just under the skin), and visceral adipose tissue (deeper abdominal fat), even when they adjust for lifestyle factors, socioeconomics, demographics, and other factors that could influence these results. (6)
POP stands for Persistent Organic Pollutant, or a pollutant that stays in the environment and builds up over time. POPs are created in some manufacturing processes, industry (including booms like during WWII), agriculture, and more, and are transported around the planet by wind and/or water. Because POPs build up over time they can have significant impacts on human health. For example, the pesticide DDT which was unregistered from use in the United States in 1972, still persists in our environment. Some people believe that exposure to POPs may one day be considered an additional official risk factor for developing type 2 diabetes. (7)
A specific POP, dioxin, has been shown to increase risk for obesity, insulin resistance, and heart disease. (8) Inflammation is one of the primary features of obesity and is one of the mechanisms in which POPs like dioxin increase risk for weight gain as well as associated metabolic conditions. They do this at the genetic level, inducing pro-inflammatory gene expression in fat cells.
We are primarily exposed to POPs in our food, especially meat, because it accumulates in animal tissues.
The Epigenetic Effect
A group at Columbia University studied pregnant women who were exposed to high concentrations of air pollutants and the effects on their children. They found when the mothers were exposed to high levels of these pollutants their children were more than twice as likely to suffer from obesity by the age of seven. This is likely due to a process called epigenetics. (9)
Epigenetic changes happen on top of your DNA that essentially turn genes on or off. You inherit your DNA from both of your parents, and you can’t change that, but you can change the way your DNA is expressed through lifestyle factors that affect your epigenome.
One comparison that some people find helpful for understanding this concept is to think of your DNA as your hardware and your epigenome as the software, where the epigenome tells your DNA what to do.
The pollutants the previously mentioned study looked at are known as polycyclic aromatic hydrocarbons (PAHs) which are created when different materials are burned (such as cigarette smoke, forest fires, grilled foods, and car exhaust). How could these products of burning result in obesity? There are likely multiple mechanisms. Alteration in the epigenome is certainly one way, but also via estrogenic activity of PAHs, and by causing fat to accumulate by blocking the breakdown of fats in the body.
The good news is the process of epigenetics can also have your back. It is the reason why your DNA is not your destiny. Epigenetic changes are not only caused by harmful things like pollution, but can be positively influenced by lifestyle factors like a healthy diet, regular exercise, and avoiding pollutants.
Where Are We Exposed to Chemicals & Pollutants?
We’ve answered this throughout, so you know the short answer is “everywhere.” There are chemicals in mattresses, laundry detergents and dryer sheets, plastics, hair products, cosmetics, air pollution, cigarette smoke, preservatives, in our food, our water, and our lawns. You cannot avoid them completely, but you can do a few things to reduce exposure and support your body’s ability to handle them.
Reducing Your Exposure
- Avoid microwaving in plastic and drinking out of plastic water bottles.
- Use good air filters in your home, car, and office.
- Eat organic.
- Eat cruciferous vegetables. Cruciferous vegetables like broccoli contain a compound called Sulforaphane which has been shown to increase air pollution excretion from the body like benzene by up to 61%! (9)
- Eat a plant-based diet. 90% of our exposure to Persistent Organic Pollutants like dioxin is through food. POPs accumulate in animal tissues, increasing our exposure when we eat more meat. If and when you do eat meat, removing the skin from fish and chicken and checking local water advisories if you catch your own fish can help reduce exposure. (10)
- Keep air-purifying plants around your home and office. NASA did a study that showed that certain plants are effective at reducing airborne benzene, formaldehyde, and tricholorethylene to near zero in 2 hours and is enhanced by carbon filter systems. (11) Check out a compiled, easy-to-use list at Wikipedia here.
- Check your cosmetics and other personal care products at the Environmental Working Group’s Skin Deep site for potentially harmful chemicals.
- See www.EWG.org or their Healthy Living app for more resources.
- Bisphenol A and the risk of cardiometabolic disorders: a systematic review with meta-analysis of the epidemiological evidence. Rancière, F, et al., et al. 46, s.l. : Environ Health, 2015, Vol. 14.
- Phthalates and metabolism: exposure correlates with obesity and diabetes in men. Phillips, Melissa Lee. 6, s.l. : Environ Health Perspect, 2007, Vol. 115, p. A312.
- Longitudinal associations between ambient air pollution with insulin sensitivity, beta-cell function, and adiposity in Los Angeles Latino children. Alderete, TL, et al., et al. s.l. : Diabetes, 2017.
- Effects of air pollution exposure on glucose metabolism in Los Angeles minority children. Toledo-Corral, CM, et al., et al. s.l. : Pediatr Obes, 2016.
- Ambient air pollutants have adverse effects on insulin and glucose homeostasis in Mexican Americans. Chen, Z, et al., et al. 4, s.l. : Diabetes Care, 2016, Vol. 39, pp. 547-54.
- Residential proximity to major roadways, fine particulate matter, and adiposity: the framingham heart study. Li, W, et al., et al. 12, s.l. : Obesity (Silver Spring), 2016, Vol. 24.
- Study links exposure to environmental pollutants to obesity, diabetes. American Diabetes Association. Alexandria, Virginia : http://www.diabetes.org, 2014.
- Abdominal Obesity and Insulin Resistance in People Exposed to Moderate-to-High Levels of Dioxin. Chang, Jung-Wei, et al., et al. 1, s.l. : PLOS ONE, 2016, Vol. 11.
- Association of Childhood Obesity With Maternal Exposure to Ambient Air Polycyclic Aromatic Hydrocarbons During Pregnancy. Rundle, Andrew, et al., et al. 11, s.l. : Am J Epidemiol, 2012, Vol. 175, pp. 1163-1172.
- Rapid and sustainable detoxification of airborne pollutants by broccoli sprout beverage: results of a randomized clinical trial in China. Egner, Patricia, Chen, Jian-Guo and Zarth, Adam. 8, s.l. : Cancer Prev Res (Phila), 2014, Vol. 7, pp. 813-823.
- Dioxins. National Institute of Environmental Health Sciences. [Online] June 2012. https://www.niehs.nih.gov/health/materials/dioxins_new_508.pdf.
- Interior landscape plants for indoor air pollution abatement. Wolverton, BC, Johnson, Anne and Bounds, Keith. s.l. : National Aeronautics and Space Administration, 1989.