Robert Lustig, MD, MSL
Professor, Pediatrics, University of California, San Francisco
Christopher Gardner, PhD
Professor (Research), Medicine, Stanford University Medical Center
April 9, 2015
When TV dinners and fast food options first appeared, they were touted as a method of liberation from the kitchen. Swapping home-cooked meals for snacks, sweets, sugary drinks, and processed foods has led to a calorie-rich, nutrient-poor diet associated with today’s rise of obesity and chronic metabolic diseases like diabetes and hypertension.
“Over the past 50 years, our relationship with food has changed dramatically. We have moved from a society that cooked at home to one that does not even know how to cook. We’ve lost a seminal component of a healthy lifestyle,” said endocrinologist Robert Lustig, MD, MSL, a professor of pediatrics at University of California, San Francisco, who spoke at a 25th-anniversary presentation sponsored by the Stanford Health Library.
Using the scientific method, Dr. Lustig pointed out the impact of processed food from multiple perspectives—on health, the environment, politics, and consumption to show that “a calorie is not a calorie.” Quick, easy, calorie-dense treats have overtaken the typical American diet, altering our metabolism, changing our biochemistry, and adding empty calories that make us crave more food without being satisfied. Since processed foods have become common, America’s obesity rate has climbed to more than 35 percent of the population.
In comparison with real food, he said, processed food has no fiber, few macronutrients, and is high in additives, emulsifiers, salt, and transfat. But the real culprit is sugar, which is added to make these products more palatable. When fat was identified as a health hazard, manufacturers replaced it with high-fructose corn syrup and other forms of sugar. Without fat to send a metabolic message of “fullness,” people started eating more and more calories — and not just empty calories but dangerous ones.
Almost 75 percent of all foods in the supermarket have added sugar. Excess sugar is found in obvious food items like candy, cookies, soda, and cereal, but it is also loaded in seemingly healthy food choices like flavored yogurt, granola, bread, “natural” food, and condiments.
“Sugar is the marker for processed food,” he said. “It’s more insidious than salt, and it hides all the other negative aspects of the food.”
Sugar makes the food taste good but masks the unpleasant flavors of other ingredients used to manufacture the product. Sugar makes up about 18 percent of the normal diet for about half the population, he added; that number should be about 4 percent. And that added sugar is detrimental to our health. The body processes food into glucose for energy and will produce it if its energy stores runs low. Fructose, on the other hand, is metabolized by the liver—too much and the fructose is converted into fat and can lead to insulin resistance. Though fructose also comes from fruit and vegetables, fiber and other nutrients counteract the effects of the sugar.
Studies have shown that about 25 percent of all cases of type 2 diabetes worldwide is caused by sugar intake alone. Most sugar today comes from soft drinks, which have also increased greatly in size over the past 30 years. EPIC interact, a large-scale international study, found that every can of soda per day increased the risk of diabetes by 29 percent. Another study found that for every extra 150 total extra calories per day, diabetes prevalence rose by 0.1 percent. But when those extra calories were from the added sugar in a can of soda, the prevalence went up by 11-fold.
“Since processed foods have been introduced there’s been a measurable rise in chronic disease. We’re paying less for food but more in health care for chronic metabolic diseases.” Dr. Lustig said. “Society is paying out more than the health industry brings in.”
Sugar’s impact is more far-reaching than just personal health, Crops used to make sweeteners, such as sugar cane, sugar beets, and corn, are taking over delicate ecosystems in the Amazon and Florida everglades. The money behind the big business of sugar production and processed food sales drive government subsidies, and efforts to tax soft drinks and sugary sweets, or limit their offerings in public schools, are often shot down by powerful lobbies.
Though sugar is never going to disappear, Dr. Lustig says that consumers need to become more diligent in what they eat and drink. For example, while sales of soda have dropped in recent years, the product has been replaced by energy drinks, which contain an equivalent amount of sweeteners.
“Don’t buy anything that lists sugar as one of its first three ingredients,” he said. “We need to bring back real food and teach people how to cook it.”
Dr. Lustig was joined after his presentation by Christopher Gardner, PhD, a renowned nutrition researcher in the Stanford Prevention Research Center. The two experts answered questions from the audience about artificial sweeteners, political aspects of processed food, and revised dietary guidelines.
About the Speakers
Christopher Gardner, PhD, is a professor of medicine in the Stanford Prevention Research Center. His work focuses on the role of nutrition and preventive medicine, with a particular emphasis on plant-based diets and phytochemicals; cardiovascular disease and cancer prevention; weight loss diets; clinical trials and epidemiology.
Robert Lustig, MD, MSL, is a professor of pediatric endocrinology who runs the Weight Assessment for Teen and Child Health (WATCH) program at the University of California, San Francisco. He is the author of “Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease” and “The Fat Chance Cookbook.” His YouTube lecture, “Sugar: The Bitter Truth,” has been viewed more than 5 million times.
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