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Your Environment. Your Health.



overweight toddler holding a measuring tape

Scientists are exploring the role that chemicals may play in weight gain and obesity.

More than 80,000 chemicals are registered for use in the United States. Some of these chemicals are toxic to animals and humans, and some interfere with how the body’s hormones function. The ones that impact hormones are called endocrine disrupting chemicals, or endocrine disruptors, and are linked to a variety of diseases.

Some endocrine disruptors have been shown to be obesogens, or involved in weight gain, and may be contributing to the obesity problem in this country. The term obesogens was coined around 2006, based on the knowledge that exposures during early development to specific chemicals were found to disrupt normal metabolic processes and increase susceptibility to weight gain across the lifespan. Poor nutrition and lack of exercise are known contributors to obesity, but these chemicals may also be contributing.

The following clinical trials are currently recruiting

How obesogens work in the body

Unhealthy diet and lack of exercise are the main factors that contribute to weight gain and obesity, but studies have found that obesogens may also be playing a role. Obesogens do not directly cause obesity, but they may increase the sensitivity, or susceptibility, to gaining weight, especially when the exposures occur during development.

Obesogens are believed to work in several ways.

They may change how a person’s fat cells develop, meaning they may increase fat storage capacity or the number of fat cells.

Also, obesogens may make it more difficult to maintain a healthy weight, by changing how the body regulates feelings of hunger and fullness, or increasing the effects of high fat and high sugar diets.

Examples of chemicals that may be obesogens

  • Cigarette smoke
  • Air pollution
  • Tributyltin, a chemical that is widely used as a fungicide and heat stabilizer in polyvinyl chloride (PVC) piping
  • Flame retardants
  • Phthalates, a broad class of chemicals that are added to many consumer products to make them softer
  • Bisphenol A
  • Some pesticides
  • Polychlorinated biphenyls (PCBs), industrial chemicals that were used widely in the past in products such as paints, cements, fluorescent light ballasts, sealants, and adhesives.

Health consequences

The most sensitive time for exposure to obesogens is during early development — as a fetus or during the first years of life — when the body’s weight control mechanisms are being developed.

Obesity is a disease itself, but other diseases or disorders that develop as a result of, or in combination with obesity, such as cardiovascular disease, liver disease, diabetes, arthritis, and others, also can contribute to health problems associated with weight gain.


Try to minimize exposures to environmental chemicals. This is often challenging, since it is hard to know where and what products contain these chemicals.

Some general advice is to:

  • Eat fresh fruit and vegetables
  • Reduce use of plastics
  • Do not use plastics in the microwave
  • Purchase furniture that has not been treated with flame retardants
  • Choose fragrance-free products

What is NIEHS Doing?

The NIEHS Obesity and Diabetes program funds numerous grantees who are studying exposures that may be related to obesity and related diseases, such as diabetes.

The National Toxicology Program is also addressing the role that chemicals play in the development of diabetes and obesity.

Further Reading

Stories from the Environmental Factor (NIEHS Newsletter)

Stories from Environmental Health Perspectives (EHP)

This content is available to use on your website.

Please visit NIEHS Syndication to get started.
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