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.

ADVERTISEMENT

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).

ADVERTISEMENT

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.”

ADVERTISEMENT

And it tended to be eaten in daylight — not because eating earlier was considered healthier, but because cooking, consuming and cleaning up is difficult in the dark or by firelight.

“People who were not rich tried to get all their meals eaten before dark. After electricity was discovered, initially only the rich could afford it,” Freedman says. “From that point onward, one mark of being rich became how late you ate. Eating way after dark because you could afford electric lights was a mark of high status, urbanity and class.”

ADVERTISEMENT

Eating late — or at random times, or more or less than thrice daily — also reflects one’s distance from the two main forces that standardized three squares in America: conventional work schedules and traditional family life.

Throughout most of the 20th century, most workers could eat only at specific times.

“When that factory whistle blew at five o’clock, it was time to go home and be fed. But now all kinds of Americans are eating later and later because they work longer hours than they used to, or because their hours are now more flexible. We are very much losing the three-meals-a-day model, thanks to grazing and thanks to different members of a household having different schedules, and to the fact that the kids might not want to eat what their parents are eating.”

ADVERTISEMENT

The idea of children being allowed to choose their own meals and mealtimes would have been shocking a few decades ago, when “Eat what’s on your plate” and “Eat your peas or no dessert” were family dinner-table mantras. But the family dinner table is verging on the obsolescent. Which came first: the dissolution of the standard nuclear family or the dissolution of three meals a day?

“American parents have a particular kind of guilt about the disappearance of family meals,” Freedman says. Perhaps for good reason: A recent University of Minnesota study found that habitual shared family meals improve nutrition, academic performance and interpersonal skills and reduce the risk of eating disorders.

Electronic devices are also undermining the three-meals model. They’re at once entertainment centers, workspaces and almost-human companions. Their portability and nonstop availability let us eat whenever we like without having to stop working, without having to be bored, and without having to feel that we are eating alone.

“The disappearance of family meals antedates the invention of hand-held electronic devices,” Freedman says. “It was not initiated by them, but it is exacerbated by them. These days, even if everyone’s sitting around a table together, it’s not clear that they’re all paying attention.”

ADVERTISEMENT

The three-meals model is also being fought by the food industry.

“The food industry wants you to buy more food,” thus it urges us to eat as much and as often as possible. It’s an easy sell, “because Americans have always liked snacks.”

A snack boom began in the mid-20th century and hasn’t stopped. Thriving through a wrecked economy, the global snack industry is predicted to be worth $330 billion by 2015. In the US alone, retail sales of packaged snacks increased from $56 billion to $64 billion between 2006 and 2010, and are expected to reach $77 billion by 2015.

The blurred borderline between snacks and meals has changed everything.

ADVERTISEMENT

“The long-term effect is that any time of day has become a time to eat. The decline of three meals a day and the rise of snacks are related, although I wouldn’t say there’s a direct causal relationship,” Freedman says.

Another food-industry strategy is the creation of food niches, based on age, ethnicity, gender, lifestyle and locale. A few decades ago, everyone ate the same foods.

“But now there’s kid food, there’s teenager food and there’s grownup food, so some parents end up buying three times as much food” as their own parents did.

“They’re being manipulated into it, guilted into thinking: I’m so busy all week and I have so little quality time with my kids that the least I can do for them is let them eat as they like rather than making a stand and insisting that we all eat the same thing together.”