The Big Gulp is the new Public Enemy Number 1.
The mayors of New York and Cambridge, the American Medical Association, and the Harvard School of Public Health have begun an assault on sugary drinks, particularly large servings of soda.
Such giant servings – the "Big Gulp" is a king-size of the 7-Eleven chain, but there are many others of its ilk – are both a direct factor in the obesity epidemic, researchers say, and a symbol of the outsize portions most Americans now eat.
Everything from the humble bagel to a slice of pepperoni pizza has more than doubled in size and calories over the last two decades.
Back in McDonald's early days, until the mid-1950s, soda was sold in 12-ounce servings; now a "small" soda under the Golden Arches contains 16 ounces and a large has 32 ounces — with more than 300 calories.
We now eat nearly 300 more calories per day today than 30 years ago — about half of those calories come from sugary drinks and another quarter from portion size increases, said Barry Popkin, a professor of nutrition at the University of North Carolina.
Why do people overeat?
In some cases it's an optical illusion, research from Cornell University has shown. When we eat out of bigger containers or plates, we don't notice that we're eating more. That's why, in one study, people ate more stale two-week-old popcorn when it was served in a big bucket compared to a small one, and why, in another study, they ate 73 percent more soup when the bowl was secretly refilled, without feeling any fuller.
"We overeat easily and under-eat with difficulty," said Susan Roberts, the director of the Energy Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. "Every study I'm aware of has shown that the bigger the portion size the greater the overeating."
It's not that you have weak willpower when you can't stop eating that giant portion of pasta in front of you, said Dr. David Kessler, a professor of Pediatrics, Epidemiology, and Biostatistics at the University of California, San Francisco.
Our brains literally can't resist. According to brain scan studies, he said, "brains get aroused and activated and stay activated until all the food is gone."
And living in a world where food is constantly available and loaded with hard-to-resist fat, sugar, and salt means constant arousal, said Kessler, former commissioner of the US Food and Drug Administration. "Our brains are being hijacked on every corner."
What should be done to control portion size?
What's needed, Kessler, Popkin, Roberts and others said, is the same kind of cultural shift that happened with tobacco — a transformation that changes the perception of overeating from an acceptable or even a glamorous pastime to deadly, disgusting habit.
We all need to stop seeing that heaping plate of food as a good value, and start thinking about it as a health hazard, said Barbara Ferrer, executive director of the Boston Public Health Commission.
"Getting that good deal may look good for our pockets, but it's bad for our health and bad for everyone's pockets," as health care costs rise, she said.
Boston isn't considering banning jumbo drinks, as New York's Mayor Michael Bloomberg announced earlier this month, and as Cambridge Mayor Henrietta Davis proposed last week. Instead, Boston has asked beverage companies to take sugary drinks out of vending machines on city-owned properties — a collaborative approach that many officials favor over Bloomberg's more confrontational style.
Voluntary improvements will be more effective in the long-term than bans, said David Just, a food and behavioral economist at the Dyson School at Cornell.
Earlier this month, for example, Disney announced voluntary plans to cut all junk-food ads from its websites, radio, and TV stations, and make its theme-park menu options healthier.
The beverage industry is also already working to reduce people's calories, said Chris Gindlesperger, spokesman for the American Beverage Association, a trade group.
High-calorie soda consumption in schools, for instance, has fallen 88 percent since 2004, when the industry agreed to change its vending machine options in schools, he said, and overall full-calorie nonalcoholic beverage consumption fell 12.5 percent between 1999 and 2010.
The Harvard School of Public Health, according to Eric Rimm, an associate professor of epidemiology and nutrition there, is among those lobbying to include soda among the products — like alcohol, cigarettes, and certain prepared foods — not covered by the federal food stamp program. More than $6 billion a year in food stamps is spent buying soda, he said.
Why target soda?
Soda is an easy first target for public health measures, researchers say, because it adds no nutritional value to the diet — no vitamins, no minerals, no protein — just calories.
Sugar-sweetened beverages, "have been a critical factor in the increased energy intake of Americans, and they've been an equally critical factor in changing the norms of the entire meal," Popkin said. "The super-size of the Big Gulp has changed people's perceptions of how much to eat in a lot of other ways."
Also, when we eat a giant, high-calorie slice of pizza, we tend to reduce our calories later in the day to somewhat compensate. But when we drink a high-calorie drink, our bodies don't "register" those extra calories, and we don't compensate for them, he said.
The other problem with sugar-sweetened drinks is the sugar. The average American consumes about 500 calories a day in added sugar, Popkin said; about 200 of which come from drinks. All that sugar day-after-day can trigger diabetes and heart disease, as well as obesity.
Cutting out soda won't immediately help most people lose weight — unless they were drinking a tremendous amount a day. But "one of the simplest strategies for people managing their weight is to cut out soda," as part of an overall weight loss plan, said Barbara J. Rolls a professor of nutritional sciences at Penn State.
Will cutting portion sizes reduce waistlines?
Surprisingly, there's very little research supporting the idea that reducing portions will have an impact on the scale.
People are amazingly creative when it comes to keeping up their calorie intake. Tell people their chips are low-fat, and they eat more of them and more the rest of the day, Cornell's Just said.
"People push back, they rebel," Just said. "They didn't get the thing they wanted so they overcompensate later and end up eating more fat later. Typically, it leads to more calories overall."
Public health officials are hopeful that downsizing meals — instead of supersizing them — will help reduce obesity. But no one really knows yet what will happen.
"I don't think overnight it will impact obesity," Rimm said, "but it's something that we need to train the next generation, that the standard portion [of soda] is not 64, 32, or even 20 oz."
Karen Weintraub can be reached at firstname.lastname@example.org