View this email in your browser

By Matthew Rees

Food and Health Fact #165: Is there more to obesity than what we eat and drink?

Follow me on Twitter: @foodhealthfacts Find all previously published Food and Health Facts here

The simplest explanation for adults gaining weight is failing to burn more calories than they’ve consumed. But what if non-biological factors contribute to weight gain? That’s the provocative question addressed by 32 researchers (most of them professors at U.S. universities) and their findings were published earlier this month in a medical journal, Biochemical Pharmacology.

They hypothesize that obesity is a growth disorder triggered by consumption of ultra-processed foods but also increased exposure to what they label “environmental chemicals.” These chemicals manipulate our metabolism and alter the setpoints at which we gain (or lose) weight. Combating obesity, they say, depends on reducing exposure to the ultra-processed foods, but also the chemicals.

That’s a tall task, on both fronts – but particularly the chemicals, which the researchers say can be found in the following products: food packaging, food and storage containers, cosmetics and personal care products, furniture and electronics, air pollution, and solvents, disinfectants, pesticides, sunscreens, plastics and plasticizers, nonnutritive sweeteners, some antidepressants and antidiabetic drugs, and common household products. They’re also found in dust and water.

In other words, they’re just about everywhere.

One such chemical is bisphenol A – better known as BPA. It’s used to coat the inside of many food cans and bottle tops (more info here). The U.S. Food and Drug Administration says it’s safe in low doses, though a meta-analysis published in 2020 identified 15 cross-sectional BPA studies and 12 of them found a “positive association” between BPA levels and obesity in adults.

A recent article in The Guardian provides a helpful explanation of how obesogenic chemicals like BPA can wreak havoc on humans:

“Obesogens work by upsetting the body’s ‘metabolic thermostat’ . . . making gaining weight easier and losing weight harder. The body’s balance of energy intake and expenditure through activity relies on the interplay of various hormones from fat tissue, the 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 article quotes Robert Lustig, one of the paper’s authors and a pediatric endocrinologist at UC San Francisco: “It turns out chemicals dumped in the environment have these side effects, because they make the cells do things that they wouldn’t otherwise have done, and one of those things is laying down fat.” (He estimates that chemicals account for about 15-20 percent of obesity.)

Increased scrutiny of how chemicals interact with the human body is greatly needed, as these chemicals have been linked to several other conditions, including type 2 diabetes, birth defects, heart disease, and autism.(Sicker, Fatter, Poorer by NYU professor Leonardo Trasande, MD, is a compelling read on the intersection of chemicals and health.)

The only risk in greater focus on chemicals is that it will detract from the biggest culprit of all when it comes to obesity: consuming too much processed food and too many sugar-sweetened beverages, along with not enough fruits, vegetables, and whole grains.

Even so, obesity is one of just many conditions that has led to the United States having the worst health outcomes of any developed country in the world – and worse than some developing countries as well. Pinpointing precisely why that is, and identifying both the remedies and the preventive tools, is one of the monumental challenges facing the United States in the years ahead.