Updated June 08, 2015.
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If you get hungry between meals, there’s no shortage of snack foods in stores and fast-food restaurants to fill you up — and no shortage of advertising claims that eating different shakes and energy bars as snacks will help you become fit and trim. We know that keeping your weight within a healthy range to avoid obesity as you get older — by consuming the right nutrients and the right number of calories — can keep many age-related diseases at bay.
Is snacking between meals really the answer?
Snacking is big business: Since the early 1980s, snack foods have exploded on the retail food market. According to analysts at Packaged Facts, a retail publication for the marketing industry, sales of packaged snacks hit $64 billion in 2010 in the United States, up from $56 billion just four years earlier. In Canada, snack food sales almost doubled between 1999 and 2009, from $1.1 billion to more than $2.1 billion, according to the federal government’s Agriculture and Food department. Snack foods are booming, despite a sluggish global economy.
Why we snack: In many countries, busier lifestyles, families doing less cooking at home, eating on-the-go, as well as a desire to eat healthier foods and lose weight, are cited as the reasons we reach for snacks.
Advice in diet books and magazines also suggests that to manage weight, keep blood glucose and insulin levels steady, and to avoid hunger later in the day, we are wise to eat more often — that is, 1-3 snacks eaten between our regular meals of breakfast, lunch and dinner.
Some nutritionists, however, believe that snacking itself is a major contributor to our growing obesity epidemic, in which 2/3 of Americans are either obese or overweight.
In 2011, for example, a team of nutrition researchers from Australia set out to answer whether eating more snacks or mini-meals in a day makes weight management easier or more effective. Published in the journal Nutrition and Dietetics, the review included 25 different studies, investigating daily eating schedules ranging from one meal a day, to 17 snacks a day. Whether food was consumed as a meal, a mini-meal, or a snack, the vast majority of the studies found no relation between eating frequency and weight loss.
Snacks and blood sugar: While people with diabetes need to carefully monitor their insulin levels throughout the day, many non-diabetics are also told in popular magazines and ad campaigns to eat frequently to keep their blood sugar stable. While some small studies in this review found eating more meals (9/day) or snacks (17/day) kept blood glucose and insulin levels more consistent, the majority found no relation between eating frequency and blood sugar in people without diabetes.
Eat more often, keep hunger at bay? Many people believe that eating more frequently can act as a kind of preemptive strike against hunger later in the day. The Australian researchers found some evidence of reduced hunger at a single meal if a snack had been eaten, but not less hunger over the entire day. In one 6-month Australian weight loss study cited, there was no difference between hunger levels whether three meals, six meals, or three meals and three snacks were eaten each day.
Eat frequently, boost metabolism? Eating itself requires energy; this is called "diet-induced thermogenesis", or the thermic effect of food. Many dieters have been told that by eating more frequently, they’ll benefit from an overall increase in their metabolic rate, and will burn off more calories than if they confined their consumption to fewer meals. However, the Australian review cites research published in the that “convincingly” refutes this notion, concluding that the frequency of meals eaten does not make an appreciable difference to the calories burned overall.
What we eat as snacks: Another problem with snack foods is that they’re typically not just smaller versions of what we eat at mealtime. More often, snacks are made up of highly-processed foods, containing greater salt, sugar and fat levels than the nutritional components of a healthy meal.
What if snacks are “healthy”? Snackers across North America say they’re looking for lower-calorie, low-fat, and higher-fiber snack foods, and manufacturers are delivering on this request. Snacks portioned out in 100-calorie packages are abundant, as are smaller plastic baggies to help you dole out your own mini-servings.
Do these downsized treats make a difference? Perhaps — if you can restrict yourself to just one. But nutrition researchers point to two potential problems.
Barbara Rolls, professor of nutritional sciences at Pennsylvania State University, warns that a risk of eating small, calorie-dense snack portions is that they don’t register with your body’s regulatory systems. Because the foods are not filling, they fly under the radar of your internal appetite sensors, making it unlikely that you’ll eat less later.
Another danger of so-called healthy snacks is that we may be inclined to eat too many of them, according to Brian Wansink, director of Cornell University's Food and Brand Lab. In his book Mindless Eating, he describes a study his team conducted, in which overweight subjects were offered snacks described as low-fat. The result? The participants ate 46% more than when the same foods had a regular label. He blames this phenomenon on our tendency to give virtuous foods a “health halo,” which offers us mental permission to over-indulge.
Bottom line: The Australian team’s review concludes that, based on the current evidence, eating more often during the day won’t help weight loss or overall health.
Finally, a group of Harvard scientists chronicling the changing eating habits of Americans concluded that eating between meals accounts for most of our increased consumption since the late 1970s. Their 2003 study, published in the Journal of Economic Perspectives, found that our increased caloric intake comes from eating more meals, not eating more calories at either breakfast, lunch or dinner.
If this is so, our best defense against weight gain is to be wary of snacks, or at least mindful about their content. If you choose to eat between meals, consider reaching only for fruits or vegetables — foods that have been proven to be part of an anti-aging diet. As an alternative, eating more at a sit-down lunch might keep your hunger in check till dinner-time.
Sources:
D.M. Cutler, E.I.Glaeser, and J.M. Shapiro. “Why Have Americans Become More Obese?” Journal of Economic Perspectives Volume 17, Number 3—Summer 2003. Pages 93–118. http://faculty.chicagobooth.edu/jesse.shapiro/research/obesity.pdf
Jessica L. Bachman, Suzanne Phelan, Rena R. Wing, and Hollie A. Raynor. “Eating frequency is higher in weight loss maintainers and normal weight individuals as compared to overweight individuals.”
J Am Diet Assoc. 2011 November; 111(11): 1730–1734.
Michelle A. Palmer, Sandra Capra, and Surinder K Baines. “To Snack or Not to Snack: What should we advise for weight management?” Nutrition & Dietetics Volume 68, Issue 1, pages 60–64, March 2011.
Rolls, Barbara and Hermann, Mindy. The Ultimate Volumetrics Diet. HarperCollins. 2012.
Rolls, Barbara J; Roe, Liane S; Kral, Tanja V E; Meengs, Jennifer S; Wall, Denise E “Increasing the portion size of a packaged snack increases energy intake in men and women.” Appetite, 02/2004, Volume 42, Issue 1, pp. 63 - 69.
"Snacking soars to $77 billion." Packaged Facts Press Release. Accessed November 23, 2012.
http://www.foodproductdesign.com/news/2011/06/snack-food-sales-soar-to-77-billion-by-2015.aspx
The Canadian Snack Food Manufacturing Industry. Agriculture and Agri-Food Canada Federal Government Public Information Sheet. Accessed November 21, 2012.
http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1172692863066&lang=eng
Wansink, Brian. Mindless Eating: Why We Eat More Than We Think. Bantam Books. 2006.