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There Is No Biological Reason to Eat Three Meals a Day -- So Why Do We Do It?

For most of history, meals were very variable.

We grew up believing in three meals a day.

When we skip meals, eat extra meals or subvert paradigms -- spaghetti breakfasts, pancake suppers -- we feel naughty, edgy and criminal. "Three meals a day" resonates like a Bible phrase.

But it's a cultural construct. 

People around the world, even in the West, have not always eaten three squares. The three-meals model is a fairly recent convention, which is now being eclipsed as, like everything else, eating becomes a highly personalized matter of choice. What and when and how frequently we eat is driven less and less by the choices of our families, coworkers and others, and more and more by impulse, personal taste and favorite nutrition memes, and marketing schemes such as Taco Bell's promotion of late-night eating known as "Fourthmeal: the Meal Between Dinner & Breakfast." Selecting how and when we eat is like loading our iPods.

A torrent of new studies explores the health effects of eating three squares. Their findings are far from conclusive. A US Department of Agriculture study found that eating just one large meal a day versus three normal-sized meals lowers weight and body fat but raises blood pressure; three meals per day lowers blood pressure. A National Institute on Aging study found that eating one large meal a day rather than three raises insulin resistance and glucose intolerance: two key features of type-2 diabetes. 

A University of Maastricht study found that eating at least four small meals daily reduces obesity risk by 45 percent. This Dutch study also found that people who skip breakfast are five times as likely to become obese as regular breakfasters. Yet a University of Ottawa study found that eating many small meals doesn't promote weight loss. So did a French National Center for Scientific Research study, which trashed grazing: "Epidemiological studies which have suggested that nibbling is associated with leanness are extremely vulnerable to methodological errors," its authors warn.

A UC Berkeley study found that "alternate-day fasting" -- feasting one day, fasting the next, ad infinitum -- might decrease the risk of heart disease and cancer. 

Researching the effects of meal frequency is notoriously tricky, because it involves so many variables: nutritional content, time of day, exercise, genetics. So the scientific jury is still out.

"There is no biological reason for eating three meals a day," says Yale University history professor Paul Freedman, editor of Food: The History of Taste (University of California Press, 2007). 

The number of meals eaten per day, along with the standard hour and fare for each, "are cultural patterns no different from how close you stand when talking to people or what you do with your body as you speak. Human beings are comfortable with patterns because they're predictable. We've become comfortable with the idea of three meals. On the other hand, our schedules and our desires are subverting that idea more and more every day," Freedman says.

For most of history, meals were very variable. A medieval northern European peasant "would start his morning with ale or bread or both, then bring some sort of food out into the fields and have a large meal sometime in the afternoon," Freedman says. "He might have what he called 'dinner' at 2 in the afternoon or 6 in the evening, or later" -- depending on his work, the season and other factors. 

"He wouldn't have a large evening meal. He would just grab something small and quick. Dinner back then tended not to be as distinct as it has become in the last two centuries."

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