Why Portion Size Really Matters…
Saturday, February 25, 2012 at 11:08AM
Dorene Robinson RDN CDN in BMI, food & exercise journal, healthy eating, portion size, stimulus control, weight management

One day at lunch time I had gone into a grocery store to get a milk. This wasn't my usual routine; I usually packed leftovers for lunch and ate at my desk while reading. But there I was standing in front of maybe ten or 15-feet of “milk section,” scanning for an 8-ounce carton of milk. Remember those? The size they used to serve with school lunch? I wasn’t finding it, when a middle-aged gentleman asked, “what are you looking for?” I looked at him and said, “I wanted an 8-ounce milk, but they don’t seem to have it.” He looked at the shelves, pointed to the smallest carton, and said, “here it is.” The carton he pointed to however was a pint (16-ounces/2 cups). I said, “no, I want one cup, that’s two.” The gentleman got a confused look on his face, glanced back at the container then back at me, and said, “that’s a cup.”

This happened about ten years ago, long after many portion sizes had morphed from recommended government standards to oversized portions (and supersizes) that apparently sold better because they appealed to our economic sensibilities.

Most of us who are old enough to remember certainly noticed portion sizes “growing” over the years. If you grew up in the 1990s or later, however, your perception of what a “normal” (physiologically appropriate) serving is, is frankly skewed. This includes restaurant meals, vending machine offerings, snack foods, “TV dinners,” soft drinks, etc., etc.

Plenty of data consistently shows that people eat more when they are served more (regardless whether it’s a larger bag of chips, bowl of soup, sandwich, burger, order of fries, etc., etc.). Same goes for buffets; it’s a rare person who doesn’t overeat at a buffet.[i],[ii],[iii],[iv]

At this point no one is arguing the fact that culture and society are a major factor in the “pressure” to passively eat (more than we did historically) as well as entice us to be less active (internet, television, video games).

Look at the change in the average weight of a 19-year-old American over the past twenty years. The average female is 5'4”, and average male height 5’9”. The average body weight for boys increased 14.1-pounds, and for girls increased 17.8-pounds. The average American 19-year-old now falls into the overweight range (based on BMI; a ratio of height to weight), where the risk for type-2-diabetes and cardiovascular disease are already increased. [View larger chart; weight data source: NHANES]

The sobering facts are that in the early 1970s the prevalence of obesity was 5% for children ages 2 to 5 years, 4% for children ages 6 to 11 years, and 6% for adolescents ages 12 to 19 years. By 2007-2008 the prevalence of obesity reached 10% for children ages 2 to 5 years, 20% for children ages 6 to 11 years, and 18% for adolescents ages 12 to 19 years.

Of course the same trend has occured in the adult population where both men and women's average weight has gone up over 24-pounds since 1960, landing the average American adult in the upper middle of the overweight BMI range. [view larger chart]

In the late 1970s 15% of adults were obese. In 2008, 34% if adults were obese. In the early 1990s zero states had an adult obesity prevalence rate of more than 25%. In 2008, 32 states had and adult obesity prevalence rate of more than 25%.


Part of the problem is that we have few “opportunities” to undereat, but seeming unlimited opportunities to overeat. Further compounding that imbalance many people don’t compensate later for larger portions consumed earlier in the day.

So what are we to do?

Implementing these techniques is a sure way to get a grip on the problems of modern portion sizes and the mindless and passive overeating that result from them.

All the best,
-Dorene

PS—test your knowledge with these portion size quizzes from the National Heart, Lung and Blood Institute. Have fun!
Portion Distortion Quiz #1
Portion Distortion Quiz #2


[i] Rolls BJ. The supersizing of America: portion size and the obesity epidemic. Nutr Today 2003;38(2):42-53.

[ii] Young, LR, Nestle M. The contribution of expanding portion sizes to the US obesity epidemic. American J Pub Health, 2002;92(2):246-249.

[iii] Diliberti N, et al. Increased portion size leads to increased energy intake in a restaurant meal. Obesity Res 2004;12:562-568.

[iv] McConahy KL, et al. Portion size of common foods predicts energy intake among preschool-aged children. J Am Diet Assoc 2004;104(6)975-979.

Article originally appeared on BeyondDiets.com (http://www.beyonddiets.com/).
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