Americans are collectively gaining weight at an alarming rate, with the average adult weighing about 15 pounds more than 20 years ago. In defining obesity, nutritionists focus on body mass index: A healthy person has a BMI of 18.5 to 24, while an obese person has a BMI above 30. Today, about 40 percent of U.S. adults and nearly 20 percent of children are obese, a surge reflected worldwide, with more people now overweight or obese (1.9 billion) than underfed (800 million). In 1985, no state in the U.S. had an obesity rate above 15 percent; now every state’s is higher than 20. Excess weight is a major factor driving runaway medical costs. Obesity-related diabetes alone “will break the bank of our health-care system,” said University of Colorado nutrition expert James Hill. “Obesity may be the toughest social issue that we have ever faced.”
What’s making us fat?
Simple: eating too much and exercising too little.
Despite constant debate over which dietary villain to blame, fat, carbs, sodium, sugar, obesity is primarily a problem of calorie intake. The average adult is eating about 300 more calories per day than in the 1970s. In 2015, for the first time, Americans spent more money eating away from home than they did on groceries, and research indicates people eat 20 to 40 percent more calories at restaurants, where portion sizes have quadrupled since the 1950s, according to the Centers for Disease Control. American calories are also largely “empty” ones — highly processed foods such as chips, white bread, and sugary cereals account for almost 60 percent of U.S. calorie consumption. Those foods, plus artificial sweeteners, may disrupt nerve signals between the gut and the brain, causing us to keep eating long after we’ve had enough. As Yale University neuroscientist Dana Small explains, it’s as if “the brain doesn’t really know the food is even there.”
Who’s most at risk?
Children, and it’s getting worse. “Addressing childhood obesity is like playing whack-a-mole,” said Harvard nutritionist Erica Kenney. Kids are spending more and more time indoors looking at screens, where they’re bombarded with advertisements for unhealthy foods. Black children see twice as many soda and candy ads as white kids do, which is just one reason why childhood obesity is racially skewed: A 2017 study showed that about 26 percent of Hispanic youth and 22 percent of black youth were obese, compared with 14 percent for white youth and 11 percent for Asian youth. Children are gaining weight faster than adults, with the obesity rate for U.S. kids ages 5 to 9 projected to hit 26 percent by 2030.
What’s wrong with weight gain?
The correlations are strong: As obesity surged over the past three decades, U.S. diabetes rates tripled, and now more than 100 million adults have diabetes or pre-diabetes.