Moreover, there was something else going on. The more sugar we ate, the more we wanted, and the hungrier we became. At New York University, Anthony Sclafani, a nutritionist studying appetite and weight gain, noticed something strange about his lab rats. When they ate rat food, they put on weight normally. But when they ate processed food from a supermarket, they ballooned in a matter of days. Their appetite for sugary foods was insatiable.
According to Jean-Marc Schwarz of San Francisco hospital, who is currently studying the precise way in which the major organs of the body metabolize sugar, this momentum creates “a tsunami” of sugar. The effect this has on different organs in the body is only now being understood by scientists. Around the liver, it coalesces as fat, leading to diseases such as type-2 diabetes. Other studies have found that sugar may even coat semen and result in obese men becoming less fertile. One researcher told me that, ultimately, perhaps nothing needs to be done about obesity, as obese people will wipe themselves out.
The organ of most interest, however, is the gut. According to Schwarz and Sclafani, the gut is a highly complex nervous system. It is the body’s “second brain,” and this second brain becomes conditioned to wanting more sugar, sending messages back to the brain that are impossible to fight.
The Sugar Association is keen to point out that sugar intake alone “is not linked to any lifestyle disease.” But evidence to the contrary appears to be emerging. In February, Lustig, Laura Schmidt and Claire Brindis of the University of California wrote an opinion article for the journal Nature, citing the growing body of scientific evidence showing that fructose can trigger processes that lead to liver toxicity and a host of other chronic diseases. In March, the New York Times reported a study that had been published in the journal Circulation, which found that men who drank sweetened beverages most often were 20 percent more likely to have had a heart attack than those who drank the least. David Kessler, the former head of the US government’s most powerful food agency, the Food and Drug Administration, and the person responsible for introducing warnings on cigarette packets in the early 1990s, believes that sugar, through its metabolization by the gut and hence the brain, is extremely addictive, just like cigarettes or alcohol. He believes that sugar is hedonic — eating it is “highly pleasurable. It gives you this momentary bliss. When you’re eating food that is highly hedonic, it sort of takes over your brain.”
In London, Tony Goldstone is mapping out the specific parts of the brain that are stimulated by this process. According to Goldstone, one of the by-products of obesity is that a hormone called leptin ceases to work properly. Normally, leptin is produced by the body to tell you that you are full. However, in obese people, it becomes severely depleted, and it is thought that a high intake of sugar is a key reason. When the leptin doesn’t work, your body simply doesn’t realize you should stop eating.