(Washington Post illustration; photos from bigstock and istockphoto)

When I was growing up in the 1960s and ’70s, snacks were occasional treats, and providing them was certainly not my parents’ priority. Nowadays, though, snacks are not just routine but often required; we parents are asked to supply snacks for sports-team practices, scout meetings and preschool parties. On school days, good parents pack a mid-morning snack and provide another for their kids to devour after school.

And snacks aren’t just for kids. Barry Popkin, a professor of nutrition at the University of North Carolina who has spent many years studying snacking, says eating outside of mealtimes has been rising for decades among both adults and children.

Popkin found, in separate studies he authored with Carmen Piernas and published in 2010, that the number of snacks children eat daily increased from slightly less than two in 1989-91 to three in 2003-06 and that adults moved from eating about 1.26 snacks daily in 1977-78 to 2.23 in 2003-06. The studies showed that snacking accounts for about 24 percent of adults’ daily caloric intake and more than 27 percent of children’s.

Popkin and other scientists are busy sorting out the health implications of all that snacking. In particular, snacking’s effect on our weight has not been made clear. Although it might seem obvious that snacks have contributed mightily to obesity, which has risen in the same period, research has yet to establish snacking as a major driver of the obesity epidemic.

Still, some data suggest it might be. In a study published in the journal PLoS Medicine last month, Popkin and researcher Kiyah J. Duffey found that the increasing number of “eating occasions” — snacks plus meals — during the day has probably played a big role in padding our middles in recent decades. The study found that from 1977-78 to 2003-06, adults added an average of 570 calories to their daily diet. In earlier years, increased portion sizes accounted for far more of those added calories than snacks did, but in later years, extra eating occasions became the leading contributor of calories.

Part of the problem is that we’re not always aware of how much we’re snacking. Marisa Moore, an Atlanta-based dietitian and spokeswoman for the American Dietetic Association, says she regularly questions new clients about their snack habits. “If they don’t divulge that information, I always ask, because people often forget. They leave out that trip to the vending machine” when describing their daily diet, “not because they’re trying to deceive me but because they just tend to overlook” their snacks.

That disconnect may stem in part from the need to come up with a clear definition of “snack.” Is a snack a certain kind of food, or a food eaten at a certain time of day? Is it a meal containing a small number of calories? Researchers haven’t agreed.

Though the first recorded use of the word “snack” to refer to a bit of food eaten outside mealtime was in 1757, according to the Oxford English Dictionary, we don’t have data about the incidence of snacking until the 1960s. Snacking began to take hold in the United States in the 1970s, Popkin says, and really took off in the ’80s and ’90s.

“In the U.S., snacking emerged gradually but really accelerated in the last 30 years,” Popkin says. That leap resulted from a combination of factors, from “unfettered” marketing to technologies allowing for the creation of new and cheap snack foods, he says. Above all, snacks have simply become ubiquitous in the marketplace, Popkin says. Whereas years ago gas stations sold only gas and grocery stores had limited supplies of snack foods, today snack-vending machines and snack-packed convenience stores are everywhere, and “you can buy snacks anyplace you go to buy anything,” Popkin asserts.

Moore, who admits she “can’t get through the day without snacks,” doesn’t advise cutting them out entirely but suggests that you “set parameters.”

“Snacking can be your friend or your enemy,” she says. “If you keep a snack drawer at your desk, it depends on what you have in it and how often you visit it. Even if it’s full of healthful food, you can still gain weight.”

Moore suggests adults have a meal or snack every three to four hours. A snack should provide 100 to 150 calories (200 tops) and should contain protein, carbohydrates and fiber. “That will keep you feeling full and energetic,” she says.

Suggestions for children’s snacks don’t generally include calorie counts but rather focus on providing key nutrients within the daily total calorie requirements, which vary from kid to kid.

Moore urges caution when it comes to liquid snacks. “Liquids are not as satiating as solids, so you go back for more more quickly,” she says. And many drinks contain more calories than you’d think. “If you’re taking in 300 to 400 calories a day from beverages,” she says, “that’s really getting in the way of weight management.”

Weight management aside, today’s constant grazing may pose another danger to our bodies. “You never have hunger control,” Popkin explains. Ideally, people should learn to eat when they’re hungry and refrain when they’re not. But the snacking phenomenon prompts us to eat when the clock tells us to, whether we need food or not. The resulting “disregulation of eating,” as he calls it, disarms our bodies’ ability to produce and follow internal hunger cues. In short, he says, “if you don’t feel hungry and you eat, you’re eating for psychological reasons. That’s where marketing comes in.”

Sensible snacks

Dietitian Marisa Moore says snacks can help people meet their daily nutrition needs. But last time I checked, the federal government’s 2010 Dietary Guidelines for Americans didn’t call for more Twizzlers and Mountain Dew.

The best snacks provide a filling mix of protein, carbohydrates and fiber, Moore says. Here are some snacks she suggests:

·Popcorn.Unless you douse it with butter and salt, popcorn – especially the kind popped on the stovetop with olive or canola oil – is a good choice for those who prefer high-volume snacks. Plus, it’s packed with fiber, so it’s filling.

·A banana or apple plus a handful — not a can-full — of peanuts. Better yet, pick pistachios: You can eat 49 of them for 160 calories, and removing the shells “slows down the eating process.

·A small apple and warm peanut butter. Take some natural peanut butter and warm it for a few seconds in the microwave,” then dip apple slices in it. Be mindful that two tablespoons of peanut butter have about 200 calories.

·Vegetables and hummus or mashed-up cooked beans with your choice of spices). Mix it up: Red pepper slices and sugar snap peas, for instance, provide lots of nutrients and fiber but very few calories. Or substitute baked tortilla chips for variety.

·A boiled egg. Plenty of protein.

·Whole-grain toast with almond butter.

·Roasted chickpeas. Drain, rinse and thoroughly dry a can of chickpeas; season with salt, pepper and olive oil and roast until they’re “crunchy and golden.”

·Melons and berries. In the heat, they’re great for hydrating and staying cool.” And 1 ½ cups have less than 100 calories.

·Smoothies. Blend plain or vanilla-flavored yogurt (or milk or tofu) with fresh or frozen fruit. Freeze it on a popsicle stick to “prolong the eating experience.”

·Sparkling water with a twist of citrus — or a few slices of fresh ginger. Or try herbal tea containing licorice, which “imparts a sweet flavor.”

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