No one has accused Americans of virtuous eating habits lately, but the sheer scale of our lust for chips, doughnuts, booze and soda still has capacity to surprise - even if you're a hard-bitten nutrition scientist.
Gladys Block, professor of epidemiology and public health nutrition at the University of California at Berkeley, recently number-crunched statistics on what Americans actually consume. She found that nearly a third of our calories come from sweets and desserts, soft drinks, alcohol, salty snacks and fruit-flavored drinks.
"I was amazed," Block said. "I mean, we knew that people eat a lot of junk food. What's important about this is the amount."
Obviously, that much snacking is likely contributing to the increased girth of Americans, she said. But (just as important to her mind) it also suggests that people are eating too many empty calories and thus not getting the micronutrients they need for optimal health.
"People can be overweight but still be undernourished with regard to vitamins and minerals and I think that's what's happening," she said.
In her study, published in the June issue of the Journal of Food Composition and Analysis, Block used two giant data-sets from an ongoing government survey known as the National Health and Nutrition Examination Survey, or NHANES. In it, thousands of adults are questioned in detail about all the food and drink they've consumed in the previous 24 hours. Participants are even given three-dimensional shapes to point at so that the serving sizes of their meals can be estimated.
The two data-sets Block used in her study include one from adults polled between 1988 and 1994, and another of people polled in either 1999 or 2000. Categorizing the foods into different groups, she found in the more recent data-set that sweets and desserts comprised 12.3 percent of calories; soft drinks, 7.1 ; and alcoholic beverages, 4.4 percent. Salty snacks and fruit-flavored drinks added an additional 5 percent to the tally.
Block saw very few differences between this later survey and the earlier one - both captured diets apparently awash with empty calories - although there was a 1 percent increase in calories obtained from soft drinks in the more recent survey.
"That doesn't sound like a lot but if you did the math it would add up to pounds gained," she said. However, she suspects that if she looked back even further, to before the sharp increase in U.S. body weight that occurred in the 1980s and 1990s, she would have seen a markedly lower contribution of snack foods to the American diet.
"These are averages," said Pat Crawford, co-director of the Center for Weight and Health at UC Berkeley. "Many people are getting an even larger percentage of their calories from these foods." She worries that adolescents, with their penchant for snacking, may be especially poor in their eating habits.
It is not just a matter of grazing between mealtimes: "These foods - although we may call them snack foods - are being eaten throughout the day and also at mealtimes as well," she said.
Perhaps the most important thing the study highlights is the need for some kind of intervention to help people clean up their diets, Block said. Studies have shown that even a quick reminder from a physician to give up smoking can increase the rate at which people do in fact quit. Could something similar be done for the diet?
"Doctors, clinics and so on need to ask people about what they're eating; that just doesn't happen very much," Block said. "It doesn't have to be a huge deal - maybe just a quick self-administered set of questions a doctor could look at then say, 'Hmm, maybe you ought to cut back on your candy bars.' It might make a difference."