Study blames chemical pollution for obesity pandemic

Obesogens are everywhere from water, dirt to food packaging, private hygiene products, house cleaners, furnishings electronics

By Madhumita Paul
Published: Monday 23 May 2022

Toxic levels of a class of chemicals called obesogens in the environment may be accelerating the worldwide obesity pandemic, according to a major scientific review.

Obesity has nearly tripled across the world since 1975. Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health. 

The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. But obesogens can alter the balance between energy intake and energy expenditure, the review found.

Data from experimental studies showed that endocrine-disrupting chemicals (EDCs) influence the development and progression of obesity.

Obesogens are a subset of environmental chemicals that act as endocrine disruptors, affecting metabolic endpoints, according to three review papers printed in the peer-reviewed journal Biochemical Pharmacology.

The proof for obesogens has been revealed by more than 40 scientists in three review papers in Biochemical Pharmacology citing 1,400 studies. They say these chemical compounds are in every single place — water, dirt, food packaging, private hygiene products, house cleaners, furnishings and electronics.

How obesogen works

Obesogens work by upsetting the body’s metabolic thermostat. The body’s balance of energy intake and expenditure through activity relies on the interplay of various hormones from fat tissue, gut, pancreas, liver and brain.

The pollutants can directly affect the number and size of fat cells, alter the signals that make people feel full, change thyroid function and the dopamine reward system, the scientists said. 

They can also affect the microbiome in the gut and cause weight gain by making the uptake of calories from the intestines more efficient.

The review identified about 50 chemical compounds as having good proof of obesogenic effects, from experiments on human cells and animals and epidemiological studies of people. These include bisphenol A, phthalates, which are broadly added to plastics. 

A 2020 analysis of 15 studies found a significant link between BPA levels and obesity in adults.

Other obesogens are pesticides, perfluoroalkyl substances (PFAs) compounds which are present in meals packaging, cookware and furnishings. 

A two-year randomised clinical trial printed in 2018 discovered a higher baseline plasma PFAS concentrations were associated with a greater weight regain, especially in women.

The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. 

This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic.

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