Thursday, December 13, 2012

The Starch Satiety Shootout: Potatoes, Baked or Mashed, Pasta, Brown Rice or Even White Bread? What's the Best After a 12h Fast? Plus: Science Round-Up Preview!

Pasta! From a satiety perspective even white bread would be a better choice for breakfast.
It's one of those Thursday's where I am alone here at the SuppVersity - no Adelfo Cerame Jr. guest lecture today. But don't worry, there will not only be another guest post next Thursday, but both, today's SuppVersity post, which is actually related to Adelfo's "Carbophobia" post from last week, as well as the SuppVersity Science Round-Up  with Carl Lanore (live at 1PM EST on the Super Human Radio Network), will compensate at least somewhat for Adelfo's absence.

Apropos Science Round-Up, I am absolutely not sure where today's show will be heading to, but I can tell you that by now it looks as if we would start out with a very recent study on the leucine <> leptin connection and it's role in getting big and ripped.

It stands to reason that the big "L"s are not going to get the job done without some sort of workout, we will then segue into the acute hormonal effects of doing cardio before vs. after a workout - something I suppose many of you who have listened to the last installment and read the follow-ups (the Seconds and the post on PGC-1 alpha-4), here at the SuppVersity, will be intrigued to hear and something on which I want to provide a little more background information with respect to the role of fasting, overall energy intake, glyogen depletion, stress and a couple of other things that will primarily effect your luteinizing hormone levels and are thus equally important for male and female SuppVersity students.

I am honestly not sure how much time will be left, afterwards, but either live at 1PM EST, or as part of tomorrows "Seconds" you will also get the chance to learn something about the little known link between nicotine (as in cigarettes) and brain aromatase, the muscle building effects of exercise induced nNOS and the certainly not advisable, but probably likewise anabolic effects of capsaicin injections. And while there is more on the list, I guess this is enough for a preview... unless you were waiting for me to mention the endocrine disrupting effects of bottled water? No!? Well, then let's finally get to the actual post ;-)

Judging carbohydrates by their GI is like adopting another man's prejudice

As I already mentioned today's post is in a way an indirect follow up on Adelfo's confession that his love-and-hate affair with carbohydrates turned into a true friendship now. I mean starches are carbs and though Adelfo explicitly said that he says a place (in moderation) for all of them in his diet, it would be nice to know a little more about the differences between the dreaded potatoes, of which I have argued before that it is in your own hands whether they will (French fries, meshed potatoes, puree, etc.; "The Potato Manifesto") turn into a problem, or not, the demonized white bread and the "healthy" - since organic and brown - starch from pasta and rice.

I guess Allan Geliebter Michelle, I.-Ching Lee, Mariane Abdillahi and James Jones from the New York Obesity Nutrition Research Center at the St. Luke’s-Roosevelt Hospital Center that's part of the Columbia University College of Physicians and Surgeons in New York, when they devised the experimental procedures for their latest study (Geliebter. 2012). And in fact their approach to the problem appears to be pretty down to earth. Instead of just measuring insulin, glucose and what-not - we have had other scientists do that before - they simply fed their twelve healthy normal-weight participants (6 male, 6 female; mean age 25.6 years,  mean BMI 22.4kg/m², mean percent body fat 19.0%) who were recruited from the Columbia University community equienergetic portions (240kcal) of starch-rich side dishes:
  • baked potato, no skin - nutrient composition as
  • mashed potato, instant - Betty Crocker Idaho potato buds
  • brown rice - Carolina natural whole grain brown rice
  • pasta - Bionature organic pasta
  • white bread - Wonder Classic Giant*
As the (*) indicates, the white bread was in there mainly as a GI standard (you usually supply GI values w/ reference to either glucose or white bread) and in order to make sure that it had it's 50g of carbs, just like all the other meals, the scientists needed so much that the overall caloric value of this "standard" meal was 33kcal higher (keep that in mind, thats ~12.5% and could therefore very well make a difference). In order to exclude any confounding variables, the water content (400g) and salt content were likewise standardized - both were added if necessary.

Pasta, rice and potatoes for breakfast?

In know, its not realistic that you have only pasta, rice, potatoes or white bread ... hold on, I know a couple of people in fact a large amount of my students eats nothing but white bread right from the baker for breakfast in their first lecture of the day :-( So it's not that unrealistic: At least we could ask ourselves would they be better off, if they ate potatoes, pasta or rice as their first meal after a 12h overnight fast, when maximal satiety is what we are looking for?
Figure 1: Hunger ratings and desire to eat from 10min before to 120min after the breakfast (Geliebter. 2012)
Well let's see, what do we have here? First off, one thing that's not in any of the graphs is the statistically significant gender bias, with the women experienced greater fullness across the test meals than men (p < 0.01). As far as the rest is concerned, the ...
  • AUC of the appetite ratings from 10 minutes before to 120min after the ingestion of the meal did not differ, and still there was a...
  • lower ‘desire to eat’ AUC following bakedpotato compared to pasta (p = 0.027) and brown rice (p = 0.004) and a much less significant advantage for rice over pasta (p = 0.041);
  • changes in fullness, however, did not differ between test meals (not shown in figure 1)
So, obviously the baked potato, which was incidentally the only food that had no nutrition label (all the rest was packaged branded and labeled), was the subjectively most satiating starch source, followed by rice and trailed by the mashed potatoe and the distant (given the overall difference) "healthy" pasta.

So, to get back to my research question, whether my real students (not you, but those at the University), would be better off eating another bland starch instead of their buns, the answer would be yes - in the long run, both brown rice and baked potatoes would qualify. 

Potato-ish insulin spikes and low GI white bread

What is interesting though, is that the spike in the "How much food could you eat now?" graph in figure 2 coincides with the early insulin spike in response to the potato meals. If you are into grazing like a cow, i.e. if you like to eat bazillions of small meals, all day long, potatoes may therefore be not your best choice.
Figure 2: Insulin after breakfast,estimation how much the participants believe the could eat and calculated GI values (based on the measured glucose response; Geliebter. 2012)
What could be downright surprising for some of you, I guess, is yet probably the fact that anyone adhering to a low GI diet, would actually have to copy my students and eat the white bread, which had the lowest GI of all the test meals ... but I guess this and the fact that pasta by far the least satiating of the 4 meals had an only 7.6% higher GI should be the nail to the real-world relevance of the glycemic index, anyway.

The non-significance of the glycemic index  was also evident during the following lunch, where the subjects were allowed to chose or simply eat both of an on an individual base already non-manageable amount of chicken or tuna salad with mayonnaise, celery, salt, and pepper that were served "in covered serving containers with openings on top to reduce visual feedback" (Geliebter. 2012) and bundled with six slices of wheat bread and six slices of seedless rye bread:
"The group mean IAUC glucose and GI using the white bread standard and adjusted for the glucose load standard are listed in table 2 . Mashed potato had the highest GI of the side dishes. The correlation between the group mean fullness AUC and the group mean GI was 0.59. The correlation between the group mean fullness AUC and the group mean lunch energy intake was –0.21. These corrrlations are not significant." (Geliebter. 2012)
Remember Peter Czerwinski, aka Furious Pete's 900g of protein in 3:30min binge (Furios Pete, 2010)? No? In that case the fact that whey is more insulinogenic than white bread is probably news to you, as well, after all, the video was part of the SuppVersity post discussing that.
So, if you intend to become friends with starches and other carbohydrates, just like Adelfo did, don't judge them by the GI value you've found in whatever online or print source. Don't fear potatoes and if you need something to count to satisfy your OCD tendencies, count total amount carbohydrates (not the rice crumbs), keep the simple sugars in check and match both of them to your personal preferences / needs.

The GI is not the "unit of food quality"

And if that's not enough counting for you, what about counting the nutritional labels on the stuff you buy? The less you have, the better your diet - after all, whole foods you buy at the farmer's market or wherever else you can still get non-industrialized real food, does not have nutritional labels ;-)

  • Geliebter A, Lee MI, Abdillahi M, Jones J. Satiety following Intake of Potatoes and Other Carbohydrate Test Meals. Ann Nutr Metab. 2012 Dec 4;62(1):37-43.