Why Nutritionists have a Hard Time Beating Obesity

[joshwriting]

Portion sizes growing with American waistlines

Food servings are bigger than 20 years ago, but most unaware, study says

All well and good, right?

A 1994 informal survey found that the standard plate size in the restaurant industry grew in the early 1990s, from 10 inches to 12.

“That holds 25 percent more food,” Schwartz said. “That really makes a difference in how much our plates can hold and how much we eat from them.”

New math?

Comments

[ratesjul.livejournal.com]

Hmmm

(pi)*5^2 = 78.5398...
(pi)*6^2 = 113.0973...

78.5398/113.0973 = .694

The bigger plate would seem to be 1.44 times the area of the other.

[murasaki99.livejournal.com]

Ha, that's better - I knew I was forgetting my geometry! And then we can get into how much volume of food one can pile upward on a plate, getting the 3-D aspect into it.

[joshwriting.livejournal.com]

right. PhD in nutrition is truly Piled Higher and Deeper!

Emperical measures?

[murasaki99.livejournal.com]

Hmm, was the nutritionist talking 25% by weight or volume? If you take the 12-in. plate as 100%, the 10-in. plate was 83% of that. So the plates grew by only 17%? Assuming I remember my really basic stuff correctly.

Of course some stuff like commercial muffins are huge compared to my standard muffin pan. I think one commercial muffin = 4 home-made ones.

Re: Emperical measures?

[joshwriting.livejournal.com]

I'd assumed area of the plate, which at best gives ratesjul's result. If you make it volume, then the change gets larger still! Cubic factors rather than merely squared.

Re: Emperical measures?

[murasaki99.livejournal.com]

That's what I thought - volume = much more. (Remembering Flatland, of all things...) The Harvard Nutrition Newsletter has lots of how commercial food portions fool the eye/brain into eating more. All I know is when I eat out, I get a doggie-bag and usually have enough for 1-2 more meals.

Re: Emperical measures?

[joshwriting.livejournal.com]

But you tend not to eat, anyway!

Re: Emperical measures?

[murasaki99.livejournal.com]

Oh no, doing much better in that dept. now. Middle age and a desk job have finally gotten me up to a thoroughly normal weight. :D Since diabetes runs in the family I'm trying not to get above-average.

Re: Emperical measures?

[dmnsqrl.livejournal.com]

sounds about where I am :)

Re: Emperical measures?

[ratesjul.livejournal.com]

And none of this takes into account the restaurant facts, such as that they don't use the whole plate - often food is either piled in the middle and sauces or oils are drizzled around the outside.
Or they use all of the inside of the plate, but none of the RIM - and the Rims can be quiet large too.

Not to mention we're assuming flat round plates - not bowls, and not square or oval or oblong dishes, all of which make a difference.

Ovals

[murasaki99.livejournal.com]

Yep, the local restaurant we patronize uses large oval plates for serving and the breakfast items like pancakes, eggs, etc., tend to be piled up several deep. I guess this is why when I did calorie calculations for (animal) nutrition class we simply did things by weight.

I have seen the 'artistic' huge plate with the rim used for Picasso-esque sauce-swirls. At least that's low-calorie... :D

A bowl is yet another wrinkle. Or mound.

Bowls

[ratesjul.livejournal.com]

Or hole

Re: Ovals

[camlina.livejournal.com]

*gutters*

backwards

[etherial.livejournal.com]

Start with what was, 10 in = 100%. Then go to what is, 12 in = 144%. So 44% more. But I agree with the people below who feel this is more about presentation than portion size.

Re: backwards

[camlina.livejournal.com]

Well, it's certainly true that US portion sizes are much bigger than in other western countries, such as France. And I don't think that they always used to be so comparably huge here.

[whatbox.livejournal.com]

I'm grateful that you are not the only person I know who'd read that and of all the implications, notice the math error immediately.

My personal filters only picked up, "No wonder trying to eat properly is still so discouraging. God, the food really is increasing in quantity."

[murasaki99.livejournal.com]

If only the food were increasing in nutritional quality, rather than just quantity. :)

[dpolicar]

A couple of restaraunts I go to regularly are of the huge-portions variety. What I actually find is that when the portion size crosses the threshold between "too large" and "absurd", I am far more likely to eat half of it (which is an entirely plausible meal) and take half of it home to eat some other time.

Not that this changes either the general consequence of larger portion sizes, or the math, but I thought I'd mention it.

Incidentally, the analysis above isn't taking into account the difference in plate-rim-width between a 10" and a 12" plate. The ratio of effective plate area would be
(PI*[(10-n1)/2]^2)/(PI*[(12-n2)/2]^2)
= [(10-n1)/(12-n2)]^2

Granted, if we want the result to be 1.25 then...
SQRT(1.25) = (10-n1)/(12-n2)
SQRT(1.25)*(12-n2) = 10-n1
SQRT(1.25)* n2 - n1 = SQRT(1.25)* 12 - 10
1.12 * n2 - n1 ~= 3.42

...which seems remarkably implausible.