Obesogens are chemicals in our environment that slow our metabolism and wreak havoc on our bodies. And in my experience, xenoestrogens (which mimic the effects of estrogen and can be found in plants, plastics, and preservatives) are the most noteworthy obesogens. Ingesting a large amount of xenoestrogens orally has a similar effect to taking birth-control pills: It causes an increase in sex hormone binding globulin (SHBG). This binding hormone not only absorbs the xenoestrogens but potentially also the body's own testosterone, which is a problem because testosterone is a terrific fat burner, and if we have lower testosterone levels, we are prone to gain weight.
While researching for my book The Secret Life of Fat, I discovered the story of "Jerry." Jerry was a very active 40-year-old who participated in a variety of sports, including water skiing and soccer. He was an adrenaline junkie and lived for extreme activities like bungee jumping and parachuting. One day he noticed he was putting on belly fat. He thought it was strange because he hadn't changed anything in his diet or exercise routine. He ramped up his workouts, but his soft belly persisted. At the same time, Jerry noticed a change in his moods—he had lost his drive and felt depressed.