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Is frequent snacking to blame for Americans’ growing waistlines?

Much has been discussed about how modern society's sedentary lifestyle is contributing to the obesity epidemic in the United States. But new research suggests our snacking habits may also be to blame.

As CNN reports, research published yesterday in PLoS Medicine shows the rise in obesity rates coincides with a trend toward frequent snacking:

According to a new study, the biggest single contributor to the sharp rise in calorie intake has been the number of snacks and meals people eat per day. Over the past 30-odd years, the study found, Americans have gone from consuming 3.8 snacks and meals per day to 4.9, on average -- a 29% increase.

The average portion size has increased, too, but only by about 12%. And, surprisingly, the average number of calories per 1-gram serving of food (known as "energy density") actually declined slightly over that period, which suggests that calorie-rich food has played a relatively minor role in our expanding waistlines.

Although the study echos previous research showing that overeating causes obesity, Stanford researcher Christopher Gardner, PhD, notes the findings could be compromised by inherent limitations. Gardner comments on these further down in the story:

Despite being nationally representative, the surveys didn't follow the same individuals over time, and in some cases also used different questions and methods, Gardner points out. Moreover, they relied on the participants' memory of what they'd eaten in the previous 24 hours, which can be unreliable.

"When people try to describe the portion sizes they are consuming, they are often inaccurate," Gardner says, adding that similar inaccuracies may crop up when recalling and calculating the energy density of specific foods.

Previously: The dark side of “light” snacks: study shows substitutes may contribute to weight gain and “Snack” offerings in restaurants may be on the rise
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