Obesogens 101: A Beginner's Guide to Hidden Chemicals Making Us Gain W

The global rise in obesity rates is one of the most significant public health challenges of our time. While diet and exercise remain cornerstone factors in weight management, a growing body of scientific evidence points towards another, often overlooked, contributor: environmental chemicals known as obesogens.

These "hidden saboteurs" are substances we encounter daily that can subtly, yet significantly, disrupt our body's natural weight control systems. Understanding what obesogens are, where they come from, and how they affect us is crucial not only for tackling the obesity epidemic but also for protecting our overall metabolic and long-term health.

This blog post aims to take a look at the complex world of obesogens. There is a lot to take in, so go slow, and spread the word after reading to the end.

What Exactly Are Obesogens?

At its core, the term "obesogen" refers to a specific category of chemical compounds that interfere with the normal development and function of metabolic processes, ultimately increasing susceptibility to weight gain and obesity.

Scientifically, obesogens fall under the broader umbrella of endocrine-disrupting chemicals (EDCs). This distinction is critical because it highlights their primary mode of action: interfering with the endocrine system.

A Little Bit About The Endocrine System

The endocrine system is a complex network of glands (like the thyroid, pancreas, adrenal glands, ovaries, and testes) that produce and secrete hormones. These hormones act as chemical messengers, traveling through the bloodstream to target cells and tissues, regulating a vast array of bodily functions.

This includes growth and development, mood, sexual function and reproduction, sleep, and, very relevant here, metabolism and energy balance. Hormones like insulin (regulates blood sugar), leptin (signals fullness), ghrelin (signals hunger), thyroid hormones (control metabolic rate), cortisol (stress hormone involved in fat storage), and sex hormones (like estrogen and testosterone, which influence fat distribution) are all key players in maintaining a healthy weight.

How Obesogens Wreak Havoc

Obesogens exert their effects by essentially hijacking or scrambling the signals within the finely tuned endocrine network. They can do this in several ways:

Mimicking Hormones: Some obesogens have a chemical structure close enough to natural hormones that enables them to bind to hormone receptors on cells, tricking the body into thinking there's more of that hormone present than there actually is. For example, some obesogens mimic estrogen, potentially promoting fat storage, particularly in certain areas of the body.
Blocking Hormones: Conversely, other obesogens can bind to hormone receptors without activating them, effectively blocking the natural hormone from doing its job. This can lead to a deficiency signal, even if hormone levels are normal.
Altering Hormone Production and Breakdown: Obesogens can interfere with the synthesis, transport, metabolism, or excretion of natural hormones, leading to abnormal levels – either too high or too low – circulating in the body.

How Disruption Translates To Weight Gain

This endocrine disruption translates into potential weight gain through several interconnected mechanisms:

Altering Fat Cell Development (Adipogenesis): Perhaps the most direct impact is on the fat cells themselves (adipocytes). Obesogens can promote the differentiation of precursor cells (preadipocytes) into mature fat cells, increasing the number of fat cells in the body (hyperplasia). They can also encourage existing fat cells to store more fat, increasing their size (hypertrophy). This effect is particularly concerning during critical developmental windows (prenatal and early childhood) when the body is setting its baseline number of fat cells.
Dysregulating Appetite and Satiety: Obesogens can interfere with the hormones that control hunger and fullness, such as leptin and ghrelin. Exposure might lead to leptin resistance (where the brain doesn't properly register the "I'm full" signal) or altered ghrelin production, potentially increasing overall food intake.
Modifying Energy Balance and Metabolism: Some obesogens may affect the body's basal metabolic rate (the energy burned at rest) or interfere with processes like thermogenesis (heat production), potentially leading to fewer calories being burned. They can also impact how the body handles glucose and lipids, favoring fat storage over energy utilization. For instance, disruption of thyroid hormone function can directly slow down metabolism.

Where Do We Encounter Obesogens?

The concerning reality is that obesogens are not rare or exotic compounds. They are found in a startling array of common products and environments. We are routinely exposed through:

Plastics: Many plastics used in food packaging, containers, water bottles, and children's toys contain known or suspected obesogens like Bisphenol A (BPA) and phthalates.
Pesticides and Herbicides: Chemicals used in conventional agriculture can contaminate our food supply and drinking water. Examples include legacy chemicals like DDT (which persists in the environment) and currently used substances like atrazine.
Personal Care Products: Cosmetics, lotions, shampoos, soaps, and fragrances often contain phthalates (to hold scent and color), parabens (as preservatives, which can have estrogenic activity), and other EDCs.
Household Items: Non-stick cookware (PFAS), flame retardants in furniture and electronics (PBDEs), vinyl flooring (phthalates), and even some cleaning supplies can be sources.
Food Supply: Beyond pesticide residues and packaging contaminants, some food processing techniques or additives might introduce obesogenic compounds. Tributyltin (TBT), an organotin compound, has been found in seafood due to its past use in marine anti-fouling paints.

Common Types of Obesogens in Our Environment

While the list of potential obesogens is long and growing as research progresses, several classes of chemicals are frequently cited due to their prevalence and documented effects. Familiarizing ourselves with these common culprits can help us identify potential sources of exposure in our daily lives and know what to avoid.

Bisphenol A (BPA)

BPA is perhaps one of the most well-known and studied endocrine disruptors. It's an industrial chemical used primarily to make polycarbonate plastics and epoxy resins.

Sources of Exposure: Polycarbonate is a hard, clear plastic often found in reusable water bottles, baby bottles (though increasingly banned for this use), food storage containers, sports equipment, and eyeglass lenses. Epoxy resins are used as protective linings inside most food and beverage cans to prevent corrosion and food contamination by metal, but BPA can leach from the lining into the contents, especially with acidic or fatty foods and heat. It's also found in thermal receipt paper, where it can be absorbed through the skin.
Obesogenic Potential: BPA is known to mimic estrogen. Studies in cell cultures and animals suggest it can promote the differentiation of preadipocytes into fat cells, alter pancreatic beta-cell function (affecting insulin release), and potentially influence appetite-regulating hormones. Studies in humans have linked higher BPA exposure levels to increased risk of obesity, type 2 diabetes, and cardiovascular issues, although establishing direct causality is complex.

Phthalates

Phthalates are a group of chemicals used primarily to make plastics like polyvinyl chloride (PVC) more flexible and durable. They are also widely used as solvents and fixatives in fragrances.

Sources of Exposure: Phthalates are ubiquitous. They are found in vinyl flooring, shower curtains, medical tubing, plastic food wrap, children's toys, and the coatings on some medications. Crucially, they are common ingredients in personal care products like perfumes, lotions, shampoos, hair sprays, nail polish, and cosmetics, often hidden under the generic term "fragrance" or "parfum" on ingredient lists. Exposure occurs through ingestion (leaching into food), inhalation (from fragranced products or off-gassing vinyl), and absorption through the skin.
Obesogenic Potential: Different phthalates have varying effects, but many are known endocrine disruptors. Some exhibit anti-androgenic activity (blocking testosterone effects), which can influence fat distribution and metabolism. Animal studies link prenatal or early life exposure to certain phthalates with later-life obesity, insulin resistance, and altered glucose metabolism. Human studies have found associations between phthalate exposure and increased waist circumference, BMI, and insulin resistance, particularly in men (due to anti-androgenic effects) but also observed in women and children.

Per- and Polyfluoroalkyl Substances (PFAS)

PFAS are a large family of synthetic chemicals valued for their resistance to heat, water, and oil. This makes them useful in a wide range of industrial and consumer products, but their strong chemical bonds also mean they break down very slowly, leading to persistence in the environment and our bodies – hence the nickname "forever chemicals."

Sources of Exposure: PFAS are used in non-stick cookware (like Teflon, though formulations are changing), grease-resistant food packaging (pizza boxes, microwave popcorn bags, fast-food wrappers), water-repellent clothing and carpets (stain guards like Scotchgard), some cosmetics, and firefighting foams. Contaminated drinking water near industrial sites or military bases is a major source of exposure for some communities.
Obesogenic Potential: Research suggests PFAS can interfere with lipid metabolism, thyroid hormone function, and glucose homeostasis. Animal studies show that prenatal exposure to certain PFAS can lead to higher body weight and body fat in offspring. Human epidemiological studies have linked exposure to specific PFAS (like PFOA and PFOS) with higher cholesterol levels, altered thyroid function, and, in some studies, increased risk of overweight/obesity, particularly when exposure occurs during development. Their interference with liver function and lipid metabolism is a key area of concern.

Organotins

Organotins are compounds containing tin bonded to carbon atoms. Tributyltin (TBT) is the most notorious example, historically used as an anti-fouling agent in marine paints to prevent barnacles and algae from growing on ship hulls. Although its use in paints is now heavily restricted in many countries due to severe environmental toxicity, it persists in sediments and can accumulate in seafood. Other organotins are used as stabilizers in PVC plastics and as catalysts.

Sources of Exposure: The primary historical route was contaminated seafood. Current exposure can still occur through persistent environmental contamination and potentially from leaching from certain PVC plastics or other industrial applications.
Obesogenic Potential: TBT is considered a potent obesogen, sometimes called the "prototypical" obesogen in research models. It activates key receptors (PPARγ and RXR) that are master regulators of adipogenesis, essentially programming stem cells to become fat cells instead of bone cells. Studies show that extremely low-level exposure to TBT during prenatal development in animals can lead to significantly increased fat storage throughout life, even without changes in diet or activity.

Pesticides and Herbicides

Many chemicals designed to control pests and weeds in agriculture have demonstrated endocrine-disrupting properties.

Sources of Exposure: Residues on conventionally grown fruits and vegetables, contaminated drinking water (runoff), and environmental exposure in agricultural areas. Legacy pesticides like DDT, though banned in many countries decades ago, are highly persistent and still found in the environment and human tissues, bioaccumulating up the food chain. Currently used herbicides like atrazine are frequently detected in water supplies.
Obesogenic Potential: DDT and its breakdown product DDE are linked to increased risk of obesity and type 2 diabetes in epidemiological studies, potentially through estrogenic or anti-androgenic actions and effects on glucose metabolism. Prenatal exposure has been associated with higher BMI in children. Atrazine has been shown in animal and cell studies to interfere with mitochondrial function (energy production) and potentially affect thyroid hormones and estrogen signaling pathways. Research links it to insulin resistance and increased abdominal fat in animal models.

Flame Retardants

Polybrominated diphenyl ethers (PBDEs) are a class of flame retardants historically added to furniture foam, electronics casings, textiles, and building materials to slow the spread of fire. While many PBDEs are being phased out due to health concerns, they are persistent and still present in older products and house dust. Newer, alternative flame retardants are also coming under scrutiny.

Sources of Exposure: Inhalation or ingestion of contaminated house dust is considered a major route. Off-gassing from treated products also contributes.
Obesogenic Potential: PBDEs are structurally similar to thyroid hormones and can disrupt thyroid function, which is critical for regulating metabolism. Animal studies link developmental exposure to PBDEs with later-life obesity, insulin resistance, and alterations in lipid metabolism. Human studies have found associations between PBDE levels and increased BMI, waist circumference, and markers of metabolic syndrome, although findings vary depending on the specific PBDE congeners studied and the population.

How Obesogens Hijack Our Body's Systems

Obesogens interfere with complex biological processes at multiple levels, often starting early in development and having long-lasting consequences.

Endocrine System Disruption

As previously mentioned, the primary mechanism of obesogens is endocrine disruption. This isn't limited to just one hormone; they can interfere with multiple hormonal axes simultaneously, creating a cascade of metabolic dysregulation.

Estrogen Pathway Interference: Many obesogens, like BPA and certain pesticides (e.g., DDT), are estrogenic, meaning they mimic the effects of estrogen. Estrogen plays a role in fat deposition and distribution. Excessive estrogenic signals can promote fat storage, particularly in subcutaneous depots, and may influence the development of fat tissue.
Thyroid Hormone Disruption: Thyroid hormones (T3 and T4) are critical regulators of basal metabolic rate, energy expenditure, and lipid metabolism. Chemicals like PBDEs and some PFAS can interfere with thyroid hormone synthesis, transport, or receptor binding. Even subtle disruptions in thyroid function can slow metabolism and promote weight gain. This is particularly concerning during brain development, where thyroid hormones are essential.
Insulin and Glucose Homeostasis: Insulin is key for regulating blood sugar levels and plays a role in fat storage. Some obesogens (e.g., BPA, certain phthalates, arsenic – another environmental obesogen) have been linked to impaired insulin sensitivity (insulin resistance), altered insulin secretion from the pancreas, and disrupted glucose uptake by cells. Insulin resistance is a hallmark of type 2 diabetes and is strongly associated with central obesity (belly fat).
Glucocorticoid Signaling: Hormones like cortisol (a glucocorticoid) influence fat metabolism and distribution, often promoting fat storage in the abdominal region, especially under chronic stress. Some obesogens may interfere with cortisol production or signaling, potentially exacerbating these effects.
Androgen Pathway Disruption: Anti-androgenic chemicals like some phthalates can block the action of testosterone. Testosterone influences muscle mass development and fat distribution. Reduced androgen signaling can lead to decreased muscle mass relative to fat mass and alterations in body composition favoring adiposity, particularly in males.

Altering Fat Cell Development and Function

Obesogens don't just affect hormones circulating in the blood; they can directly target the biology of fat cells (adipocytes) and their precursors.

Promoting Adipogenesis: This is a key mechanism for compounds like TBT and potentially others like BPA and certain phthalates. They activate molecular switches, primarily the peroxisome proliferator-activated receptor gamma (PPARγ), which is a master regulator that tells undifferentiated mesenchymal stem cells to become preadipocytes, and tells preadipocytes to mature into fat-storing adipocytes. By promoting adipogenesis, especially during critical developmental windows (prenatal, infancy), obesogens can permanently increase the body's total number of fat cells. A higher number of fat cells makes it easier to gain weight and harder to lose it later in life.
Increasing Fat Storage (Lipogenesis): Beyond creating more fat cells, obesogens can influence the biochemical pathways within existing fat cells, encouraging them to take up and store more lipids (fats). They might interfere with the opposing process, lipolysis (the breakdown of stored fat for energy), tipping the balance towards net fat accumulation.
Altering Adipokine Secretion: Fat tissue is not just passive storage; it's an active endocrine organ itself, secreting hormones called adipokines (like leptin and adiponectin) that influence appetite, insulin sensitivity, and inflammation. Obesogens can potentially alter the production and secretion of these adipokines, contributing further to metabolic dysregulation.

Genetic Changes

One of the most concerning aspects of obesogen action is their potential to cause epigenetic changes. Epigenetics refers to modifications to DNA or its associated proteins that change gene expression (which genes are turned on or off) without altering the underlying DNA sequence itself. These modifications can be influenced by environmental factors, including chemical exposures.

Developmental Programming: Exposure to obesogens during sensitive developmental periods (prenatal and early postnatal life) can induce epigenetic marks on genes involved in metabolism, fat cell development, and appetite regulation. These changes can essentially "program" the individual for increased susceptibility to obesity and related metabolic diseases later in life, even if exposure ceases. For example, exposure to TBT or BPA in utero has been shown in animal models to cause epigenetic alterations that persist into adulthood, correlating with increased adiposity.
Transgenerational Potential: Even more startling is the possibility that some epigenetic changes induced by obesogens could be passed down through generations. While more research is needed, some animal studies suggest that the metabolic phenotypes (like obesity or insulin resistance) caused by ancestral exposure to certain EDCs can persist for several generations, transmitted via epigenetic marks in the sperm or eggs. This raises significant long-term public health concerns.

Wider Health Implications of Obesogen Exposure

While the term "obesogen" directly links these chemicals to weight gain, their impact extends far beyond simply adding pounds. Because they disrupt fundamental hormonal and metabolic pathways, exposure to obesogens is increasingly associated with a range of serious health conditions, often intertwined with obesity itself, but sometimes occurring independently.

Increased Risk of Type 2 Diabetes

The link between obesogens and type 2 diabetes is particularly strong, stemming from their effects on insulin sensitivity and glucose metabolism.

Insulin Resistance: As discussed, chemicals like BPA, certain phthalates, PFAS, and arsenic can interfere with insulin signaling, making cells less responsive to insulin's instructions to take up glucose from the blood. This insulin resistance forces the pancreas to produce more insulin to compensate. Over time, this can exhaust the pancreas, leading to impaired glucose tolerance and eventually overt type 2 diabetes.
Pancreatic Beta-Cell Dysfunction: Some obesogens may directly harm the insulin-producing beta cells in the pancreas, impairing their ability to secrete insulin appropriately in response to blood sugar levels.

Cardiovascular Disease Concerns

Metabolic disruption caused by obesogens can also negatively impact cardiovascular health.

Hypertension: Some studies have linked exposure to certain obesogens, including BPA and PFAS, with an increased risk of high blood pressure. Mechanisms could involve direct effects on blood vessel function, kidney function, or interactions with hormonal systems that regulate blood pressure.
Dyslipidemia: Obesogens like PFAS and potentially phthalates have been associated with altered blood lipid profiles, such as elevated levels of LDL ("bad") cholesterol or triglycerides, and lower levels of HDL ("good") cholesterol. Abnormal lipid levels are a major risk factor for atherosclerosis (hardening of the arteries).
Atherosclerosis and Heart Disease: By promoting obesity, diabetes, hypertension, and dyslipidemia – all major risk factors for heart disease – obesogens indirectly increase the risk of heart attacks, strokes, and other cardiovascular events. There might also be direct effects on inflammation and endothelial function (the health of blood vessel linings) that contribute to atherosclerosis.

Links to Certain Cancers

The endocrine-disrupting nature of many obesogens raises concerns about their potential role in hormone-sensitive cancers.

Estrogen-Related Cancers: Chemicals that mimic estrogen (like BPA, DDT) could potentially promote the growth of cancers sensitive to estrogen, such as certain types of breast cancer, uterine cancer, and ovarian cancer. While human evidence is complex and often confounded by other factors, the biological plausibility is strong, and animal studies support these links.
Other Cancers: Some obesogens might influence other cancer types through mechanisms involving inflammation, altered cell growth signaling, or epigenetic changes that affect cancer-related genes. For instance, disruptions in metabolic pathways could potentially fuel cancer cell proliferation. Research in this area is ongoing.

Thyroid Dysfunction

As noted earlier, chemicals like PBDEs and PFAS can interfere with thyroid hormone production, transport, or action. Thyroid hormones are essential not only for metabolism but also for brain development, growth, and overall cellular function.

Hypothyroidism/Hyperthyroidism: Disruption can lead to either underactive (hypothyroidism) or, less commonly, overactive (hyperthyroidism) thyroid function, requiring medical management.
Developmental Effects: Thyroid disruption during pregnancy and early childhood can have severe consequences for neurodevelopment and growth.
Metabolic Consequences: Even subclinical thyroid dysfunction can affect weight management, energy levels, and cholesterol metabolism.

Immune System Effects and Inflammation

Emerging research suggests some obesogens may also impact the immune system.

Altered Immune Response: Exposure has been linked in some studies to changes in immune cell populations or function, potentially affecting susceptibility to infections or autoimmune conditions.
Chronic Inflammation: Obesity is associated with a state of low-grade chronic inflammation, which contributes to many chronic diseases. Obesogens might exacerbate this inflammation, either indirectly through promoting obesity or potentially through direct effects on inflammatory pathways.

Strategies to Reduce Obesogen Exposure

While completely eliminating exposure to obesogens is likely impossible, significantly reducing our contact with these chemicals is achievable through conscious choices and proactive measures. Focusing on the major sources and pathways can make a meaningful difference to our cumulative exposure load.

Making Safer Product Choices

Scrutinizing the products we bring into our homes and put on our bodies is a critical first step.

Rethink Plastics, Especially for Food:

Prioritize Glass and Stainless Steel: Use glass or stainless steel containers for storing food and beverages, especially for hot items or liquids. Choose stainless steel or glass water bottles over single-use plastic ones. Reusable plastic bottles are also a good choice.
Avoid Certain Plastic Codes: If using plastic, try to avoid types commonly associated with BPA (recycling code #7 or 'PC') and phthalates (code #3 or 'PVC'). Codes #1, #2, #4, and #5 are generally considered safer alternatives, but avoid heating food in any plastic container.
Look for "BPA-Free" (with Caution): While "BPA-free" labels are helpful, be aware that some substitute chemicals (like BPS or BPF) may have similar endocrine-disrupting properties. Glass or stainless steel remain the safest options.
Ditch Plastic Wrap: Use beeswax wraps, silicone lids, or simply place food in reusable containers instead of using plastic cling film, especially directly on food.

Choose Natural or Organic Personal Care Products:

Read Ingredient Lists: Opt for products with shorter, recognizable ingredient lists. Avoid items listing "fragrance" or "parfum" unless the source is specified as natural essential oils. Look for products explicitly labeled "phthalate-free" and "paraben-free."

Utilize Databases and Apps: Resources like the Environmental Working Group's (EWG) Skin Deep database can help you assess the safety of ingredients in specific personal care products.

Consider Simpler Routines: Sometimes, using fewer products overall is the easiest way to reduce chemical exposure.

Modifying Dietary Habits

Since diet is a major exposure route, making informed food choices can have a significant impact.

Prioritize Organic Produce When Possible: Choosing certified organic fruits and vegetables helps reduce exposure to synthetic obesogenic pesticides and herbicides. If organic isn't always feasible, focus on buying organic versions of produce known to have higher pesticide residues (consult resources like the EWG's "Dirty Dozen" list) and thoroughly wash all produce. Field of Greens superfood powder is highly touted for the inclusion of organic ingredients to support your fight against these obesogens. Recommended to take daily.
Limit Processed and Packaged Foods: These items often come in packaging containing BPA or phthalates, may contain PFAS from grease-proof coatings, and can have various additives. Cooking meals from whole, fresh ingredients minimizes these exposures.
Reduce Canned Food Consumption: Opt for fresh or frozen foods over canned goods whenever possible. If using canned items, look for those in BPA-free lined cans or packaged in glass jars or Tetra Paks. Rinsing canned beans or vegetables might help reduce leached chemicals.
Filter Your Drinking Water: Use a high-quality water filter certified to remove common contaminants, including potential EDCs like BPA, pesticides, PFAS, and chlorine byproducts. Activated carbon filters are generally effective for many organic chemicals. Consider reverse osmosis systems for broader contaminant removal, including PFAS.
Choose Leaner Meats and Trim Fat: Some persistent organic pollutants accumulate in animal fat. Choosing leaner cuts of meat and trimming visible fat can help reduce exposure. Consider sources of meat and dairy raised without routine use of hormones or antibiotics.

Budget-Friendly Exposure Reduction

Reducing obesogen exposure doesn't have to be expensive. Many effective strategies are low-cost or even save money.

DIY Cleaning: Switch to inexpensive staples like white vinegar (diluted with water) for general cleaning and glass, and baking soda for scrubbing. Add a few drops of essential oil like lemon or tea tree for scent if desired (use caution around pets).
Cook from Scratch More Often: Preparing simple meals at home using fresh ingredients is often cheaper and healthier than buying processed or packaged foods and reduces packaging exposure.
Prioritize Water Filtration: While upfront costs vary, filtering tap water is usually much cheaper in the long run than buying bottled water and reduces plastic waste and potential leaching. A simple activated carbon pitcher filter is a good starting point.
Focus on High-Impact Food Swaps: If buying all organic isn't feasible, focus on reducing intake of the most heavily treated produce (referencing lists like the "Dirty Dozen") or prioritize organic options for foods you eat most frequently. Wash conventional produce thoroughly.
Choose Whole Foods: Base your diet around minimally processed foods like vegetables, fruits, whole grains, legumes, nuts, and seeds, which are naturally lower in additives and packaging contaminants.
Stop Buying Air Fresheners: Simply opening windows is free and more effective at improving air quality.
Gradual Replacement: Don't feel pressured to replace everything at once. As items wear out (like cookware or food containers), replace them with safer alternatives (cast iron, stainless steel, glass).

Final Words

So, is it possible to avoid these chemicals completely? It’s very difficult. This is especially true since many commodities just don’t highlight the presence or use of these compounds, and information about the same is sparse.

This is why you need to be proactive about what you can control. Start minimizing your known exposure and see if this makes the change you seek.

Obesogens 101: A Beginner's Guide to Hidden Chemicals Making Us Gain Weight