Understanding Obesogens
Key takeaways from the article, Obesogens: a unifying theory for the global rise in obesity, by J. Heindel, R. Lustig, S. Howard, and B. Corkey.
Why this article matters:
Obesity rates continue to climb globally even with updates to science, drugs, and diets. It’s crucial for us to understand the true causes of obesity if we really want to combat it. My general understanding of why people gain weight has been more along the lines of the energy balance model (EBM), calories in (the food you eat) should be less than or equal to calories out (calories used in exercise/daily living). The EBM model put’s ownership on the individual to maintain their own weight by counting calories and exercising enough.
This article tells a different story; it also matters what you eat and what you are exposed to. There are other things contributing to the manifestation of obesity, called obesogens. Obesogens are chemicals that affect the way the human body makes, stores, and uses fats by disrupting hormone regulation. This article highlights that exposure to obesogens occurs both on and off the plate, like pesticides, microplastics, aromatics like candles and perfumes, chemicals in cleaning supplies and skin care. Obesogens are all around us.
Adjusting the diet and exercise is important, but so is eliminating exposure to air pollution, toxins from household cleaning supplies, skin care, makeup, etc. We as individuals can only control so much, like choosing the products we buy, eating organic, and getting appropriate exercise. As a society we also need support from the macro level. Governments need to take ownership of things like air pollution, ultra-processed food manufacturing, and water contamination. Corporations need to understand what goes into their products and how it affects the human body. If policies and practices don’t change now, obesogens will continue to be pervasive in our society and obesity rates will continue to rise.
Current four general models of how obesity happens:
Energy balance model (EBM): the general calories in, calories out model. Calories as the only factor contributing to weight gain. This model puts its emphasis on the combination of overeating and a sedentary lifestyle. This model notes ultra-processed food (UPF) as a contributor to overeating, insulin resistance and hyperinsulinism, and weight gain.
Carbohydrate-insulin model (CIM): metabolic function in weight gain. Elevated insulin (hyperinsulinemia) creating excess energy (carbohydrate) storage as fat deposits. This model also acknowledges that excess nutrient intake, UPF, refined carbohydrates, low-fat diets, and fructose sweeteners are contributors to metabolic dysfunction and weight gain.
Oxidation-reduction model (REDOX): reactive oxygen species (ROS) (byproduct of cellular metabolism, free radicals, body messengers) cause altered metabolic signaling and endocrine disruption.
Obesogens model (OBS): environmental chemicals, especially during critical points in development, that interfere with hormone signaling which causes increased fat deposit. There are many types of identified obesogens - metals, viruses, prescription drugs, environmental (plastics, chemicals like BPAs, insecticide/pesticide), food related (fructose, trans-fats, preservatives, emulsifiers), non-stick coatings like polyfluorinated stubstances (PFAS), clothing particles, personal care products, air pollutants, and many more.
How does obesity start? Likely childhood, or even before.
Children whose parents were overweight or underweight during pregnancy saw the highest likelihood for obesity, especially children whose mothers qualified as obese pre-pregnancy.
Nutrition, stress, and environmental chemicals alter metabolic signaling and epigenetics throughout the lifespan but can be exceptionally impactful in utero and childhood.
Obesity has reached epidemic levels over the past 50 years. However, 50-70 years ago, people were eating about the same quantity of food, the exposure to obesogens is what has changed.
The article’s proposed edit to the understanding of how obesity happens:
A combination of the above models. First combining the OBS and REDOX models, then including the EBM and IM models. The idea that chemicals within the environment (air, cleaning products, skincare, food and food packaging) create changes in the bodies autocrine and endocrine signaling causing changes to metabolic function, energy storage (carbohydrate/sugar/fat storage), insulin levels, appetite, and energy output, which all together causes weight gain.
OBS/REDOX combination – obesogens have entered the body and caused endocrine disruption and altered body signaling. The body receives misinformation which causes abnormal insulin secretion, fat storage, brain regulation and energy balance. As a person develops these obesogens change hormones, most significantly hormone timing, and ROS alter gene expression, resulting in different epigenetic outcomes. Hormone differences and increased ROS result in increased insulin (hyperinsulinism) and insulin resistance, altered fat cell differentiation, size, and number, inflammation, fat deposits in the liver (non-alcoholic fatty liver disease, NAFLD), altered gut microbiome, altered resting metabolic rate (commonly referred to as metabolism), and reduced desire to voluntarily expend energy (sedentary lifestyle).
Obesogens can increase inflammation contributing to the low-grade chronic inflammation seen with other chronic diseases like cardiovascular disease and type 2 diabetes.
The Western diet is high in obesogens (chemicals, UPF, emulsifiers, preservatives). Consuming this diet will increase inflammation and affect cell function, encourage hyperinsulinism, and reduce insulin sensitivity. This is why citing the EBM or CIM models for obesity are not sufficient in explaining the current state of obesity. If caloric intake or metabolic function was all that mattered, obesity would not be as pervasive. The OBS/REDOX model cites that quality of diet matters just as much as the quantity.
Final summary of the integrated model of obesity:
The final summary proposes that both diet (especially the Western diet) and obesogens create the newer obesity model. Diet (again, especially the Western diet), stimulates overeating and insulin secretion, leading to fat deposits and weight gain. Those who are exposed to obesogens during development, particularly in utero and childhood, have altered metabolism and an ability to gain weight more easily due to altered epigenetics. Exposure to obesogens also impact hormones and ROS throughout the lifespan. This causes increased fat tissue, abnormal fat cell size, number, function, and cell growth, insulin differences (increased secretion and resistance), altered hunger cues, altered microbiome, and overall body inflammation.
My most impactful take-home quotes from the article:
“The OBS-REDOX model provides a focus on factors in the environment that could be responsible for instigating obesity (i.e., obesogens), the sites and mechanisms by which these chemicals might alter brain circuits controlling food intake (ROS and redox signals), and why some individuals are more susceptible to weight gain (differential exposures to obesogens, different ROS-scavenging capacities).”
“The REDOX-OBS model focuses on the effects of obesogenic chemical exposures during development and how they send false autocrine and endocrine signals in metabolic tissues, increasing the sensitivity or susceptibility to weight gain later in life and even across generations.”
“Misleading cellular signals will stimulate food consumption, insulin release, and fat storage even when fuel is not excessive.”
“The acceptance of this integrated model will focus on preventing obesity by reducing exposures to obesogens in utero and early life and throughout the lifespan. These include eating fresh organic foods, avoiding UPF, avoiding plastics for storing or heating food, using fragrance-free products, avoiding nonstick cookware, and using purified drinking water (for details, see www.ewg.org). Ultimately, regulatory and policy action will be needed to reduce the production of obesogenic chemicals.”
Ways you can reduce your obesogen exposure:
“Clean” home products - reduced chemicals or chemical-free products
“Clean” beauty products - reduce the amount of unnecessary chemicals put on the skin and hair
Reduce scented products - scents are endocrine disruptors, modifying the metabolic function.
Purify the air - no candles/incense, reduce pet allergens, reduce pollution and allergens from the outside.
Eat organic as much as possible, clean your fruits and vegetables with water and vinegar.
Avoid ultra-processed foods
Use stainless steel, ceramic, wood, and glass for food preparation and storage.
Citation:
Heindel, J.J., Lustig, R.H., Howard, S. et al. Obesogens: a unifying theory for the global rise in obesity. Int J Obes (2024). https://doi.org/10.1038/s41366-024-01460-3
