Part 1 of “The Skinny on Fat” discussed the why industrial cooking oils made from corn, soybean and Canola as well as animal foods that have been fed corn and soy are primary contributors to America’s epidemics of obesity, heart disease, diabetes and cancer. Part 2 examined the second major contributor to our growing waistlines and failing health: the extreme quantity of soda, bread, pasta, potatoes, cereal, and sweets Americans consume every day.
This week, in Part 3, I’d like to point the finger at a third, very dangerous culprit in our struggle with obesity, heart disease, diabetes and cancer:
It’s easy enough to point the finger at our national addiction to sugar and carbohydrates, not to mention our increasingly sedentary lifestyles, when trying to find a cause for our epidemic of “lifestyle diseases” like obesity. Potent as they are, however, these causes cannot explain the ballooning of one particular segment of the population—a segment that can’t chew, and was never that much into exercise: babies.
In 2006, scientists at the Harvard School of Public Health reported that the prevalence of obesity in infants under 6 months of age had risen 73 percent since 1980. “This epidemic of obese 6-month-olds,” as endocrinologist Robert Lustig of the University of California, San Francisco, calls it, poses a problem for conventional explanations of the fattening of America. “Since they’re eating only formula or breast milk, and never exactly got a lot of exercise, the obvious explanations for obesity don’t work for babies,” he points out. “You have to look beyond the obvious.”
According to Dr. Bruce Blumberg, professor of developmental and cell biology and pharmaceutical sciences at the University of California in Irvine, there’s growing evidence that suggests that some of the chemicals used in everyday items predispose an individual to the battle of the bulge, despite normal diet and exercise.
Scientists describe these chemicals as “obesogens” because of way they effect how we develop and store fat.
An Inside Look at “Obesogens”
The scientific results from multiple laboratories are preliminary, yet, the data all say the same thing: Chemicals that affect our hormone system—often called endocrine-disrupting chemicals—are playing some role in the global epidemic of excessive weight.
“Despite what we’ve heard, diet and exercise alone are insufficient to explain the obesity epidemic,” says Blumberg. As Blumberg, co-author of a review article in the August 2009 issue of Molecular Endocrinology called “ The Case for Obesogens. ” points out, “the obesity epidemic roughly correlates with the rise in the use of industrial chemicals, including plastics and pesticides, following World War II.”
These industrial chemicals act on genes in the developing fetus and newborn to turn cells that would normally become connective tissue into fat cells, which stay with you for life. And they may alter metabolic rate, so that the body hoards calories rather than burning them.
In 2006, Blumberg fed pregnant mice tributyltin, a disinfectant and fungicide used in disposable diapers, marine paints, plastics production, and other products, which enters the food chain in seafood and drinking water. “The offspring were born with more fat already stored, more fat cells, and became 5 to 20 percent fatter by adulthood,” Blumberg says.
Genetic tests revealed how that had happened. The tributyltin activated a receptor called PPAR gamma, which acts like a switch for cells’ fate: in one position it allows cells to remain fibroblasts for connective tissue, in another it guides them to become fat cells. (It is because the diabetes drugs Actos and Avandia activate PPAR gamma that one of their major side effects is obesity.) The effect was so strong and so reliable that Blumberg thought compounds that reprogram cells’ fate like this deserved a name of their own: obesogens.
As later tests would show, tributyltin is not the only obesogen that acts on the PPAR pathway, leading to more fat cells. So do some phthalates (used to make vinyl plastics, such as those used in shower curtains and, until the 1990s, plastic food wrap), bisphenol A, and perfluoroalkyl compounds (used in stain repellents and nonstick cooking surfaces).
Programming the fetus to make more fat cells—or adipocytes —leaves an enduring physiological legacy. The more adipocytes, the fatter you are. But adipocytes are more than passive storage sites. They also fine-tune appetite, producing hormones that act on the brain to make us feel hungry or satisfied. With more adipocytes, an animal is doubly cursed: it is hungrier more often, and the extra food it eats has more places to go—and remain.
Within a year of Blumberg’s groundbreaking work, it became clear that altering cells’ fate isn’t the only way obesogens can act, and that plastics and pesticides aren’t the only potential obesogens. In 2005 experiments began feeding newborn rats genistein, an estrogen-like compound found in soy, at doses like those in soy milk and soy formula. By the age of 3 or 4 months, the rats had higher stores of fat and a noticeable increase in body weight. And once again, mice fed genistein did not eat significantly more—not enough more, anyway, to account for their extra fat, suggesting that the soy compound threw a wrench in the workings of the body’s metabolic rate. Says Blumberg, “One of the messages of the obesogens research is that prenatal exposure can reprogram metabolism so that you are predisposed to become fat,” says Blumberg.
Hormone-mimicking chemicals already have a bad rap for their role as endocrine disruptors in the body (including the notorious bisphenol A (BPA) that has led to the shunning of plastic water bottles nationwide). We’re surrounded by these chemicals: BPA and pthalates are everywhere, from water bottles to dryer sheets to the PVC pipes that deliver your shower water, and they’re taking their toll. It’s not an accident that many fish and frogs are born with sexual deformities, girls are reaching puberty earlier, fewer boys are being born than ever before, and infertility and sexual dysfunction plague adult men and women alike. Endocrine disruptors are pernicious toxins with far-reaching, dangerous effects that we are only beginning to fully understand.
The chemicals that were linked to weight gain and hormone disruption include:
What Can You Do?
Certainly, we can take individual steps to reduce our exposures to hormone-disrupting obesogens. To name a few:
Chemical poisoning is a problem that is truly not easy to solve. The long-term solution to our toxic problem requires a fundamental shift in the way we use industrial chemicals so that public health and environmental protections are the top priorities. For example, the European Union recently instituted sweeping changes that mean chemical companies will lose access to the EU’s 500 million consumers and $11 trillion (US) market unless they can prove their substances do no harm.
Here at home, it’s time to ask Congress to create common sense limits on toxic chemicals. Contact your Congressperson to urge them to pass the Kid-Safe Chemicals Act, which would require that all chemicals be proven safe for children before they can be sold.
It makes no sense to continue to release untested chemicals into the marketplace, only to end up chasing down the ones that cause harm to people and ecosystems long after the damage has been done.
Further info on endocrine-disrupting chemicals:
This post is part of Fight Back Fridays hosted by Food Renegade!
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