Lately we’ve been hearing a lot about the toxic food environment. Typically this refers to the widespread availability of cheap, tasty, high calorie, sugar and fat laden foods that make it likely that we’ll eat more than we need. Fast food restaurants, TV commercials, and the easy availability of snack foods are thought to contribute to the obesity epidemic. What is less well known is that there may be actual chemical toxins in the environment that cause weight gain and make weight loss more difficult.
Several recent studies have pointed to non-natural compounds that may contribute to weight gain. For example, researchers at The Mount Sinai Medical Center in New York found a link between exposure to phthalates and obesity in children. Phthalates are chemicals that can mimic human hormones. They are found in plastic flooring, wall coverings, and personal care products like perfume, cosmetics and lotions. They’re also sometimes used in the coatings of drugs or supplements.
The Mount Sinai researchers measured phthalate concentration in the urine of 387 New York kids and measured BMI, height and waist circumference a year later. The urine tests showed that almost all the children had been exposed to phthalates. There was a relationship between the concentrations of phthalates and BMI and waist circumference among the overweight children. Since the study’s findings are correlational it will take additional research to establish that the phthalates were responsible for the weight gain.
Several other studies have suggested that organochlorines (OCs) like DDT promote weight gain and make weight loss more difficult. DDT is an insecticide that was used in agriculture but was banned in 1972. It has an exceptionally long half-life. After several decades it is still detectable in the food chain, especially in dairy, meat, and fish. As recently as 2005, the Centers for Disease Control found traces of DDT in virtually all of the human blood samples they tested.
Researchers at Laval University in Quebec found that a dieting and exercise program resulted in a weight loss but led to increased plasma concentrations of OCs. In one recent study the researchers found that sleeping metabolic rate decreased with increased plasma concentrations of OCs. In other words, when you lose weight there is less fat tissue to dilute DDT and other OCs so they are more concentrated and have a greater effect on your metabolism. When your resting metabolism decreases it’s easier to regain the weight even if you don’t eat more.
There is little doubt that all the external food cues in our environment are responsible for much of the dramatic increase in obesity. It’s likely that some non-natural chemicals in the environment also contribute to the obesity epidemic by making it easier to gain weight and more difficult to lose it.