The Potato Manifesto - Part 1/2: A (Re-)Evaluation of the Contemporary Discrimination of "the" Ordinary Potato

Image 1: The grunty regular (left) and the cute sweet potato (left), which one would you commit your health to? (img. menshealth.co.uk)

This is a blogpost, which eventually turned out to be the first part of a series, is a post with a history, a rather complex one, to be precise. It is rooted (not tubered ;-) in my amazement over the contemporary craving for sweet potatoes within the ever-growing neo-paleolithic community on the Internet and was sparked by the recent publication of a study on sweet potatoes, I stumbled upon on my daily tours of the most recent scientific literature. To make long story short, instead of immediately summarizing the data, drawing some graphs and commenting on the real-world implications of this study, I decided to use the holiday to descend into the archives and take a closer look at what science has to say on the bitter truth about the grunty regular and the starchy promises of cute sweet potato (cf. image 1 ;-)...

When wheat was devils excrement, would regular potatoes then be his horns?

According to the official obesity statistics of the European Union, British women are the fattest in Europe (Eurostat. 2011): 23.9% were classified as being obese (BMI > 30) in the year 2008 to 2009. This certainly raises the not altogether serious question, whether the British obesity problem (the obesity rate among the men was 22.1% and thusly topped only be the Maltese with 24.7%) is due to the fried fish or the fried (regular) potatoes in the unofficial British national dish, fish & chips.

Image 2: Obese British woman's rear view (img. BBC.co.uk)

A note to my dear American friends: Don't crow too soon, the obesity rate in the US tops the one in the UK by more than just a margin. According to a 2010 paper by Flegal et al. that was published in the Journal of the American Medical Association, the estimated obesity rate in the US amounts to 35.5% among the women and 32.2% among the men (Flegal. 2010). And a constantly increasing percantage (currently 4.7%) of the American population is already "extremely obese" and has a BMI > 40! Just to put that into perspective. A man or woman with a BMI beyond 40 and a height of 5 foot and 7 inches (170cm) would weigh at least (!) 254.85lbs (115.6kg) - this is already "Kig-Size Homer"-territory (cf. Intermittent Thoughts).

If we follow the current dietary paradigms and ignore the frying procedure, the answer to this question does not appear to be very difficult. I mean, when wheat was devil's excrement, then regular potatoes would be his horns or even nastier body parts, I do not want to mention here... and though a reasonable explanation for the widespread vilification of potatoes still escapes me, the contemporary nutritional paradigm within the health and nutrition blogosphere suggests that regular white potatoes have an awfully high glycemic index, will spike your blood sugar levels and have your neolithic body pump out tons of insulin - even if the rest of your diet is 99% paleo, as many of the listeners of Robb Wolf's podcast like to describe the way they are eating after having read his (widely read, yet controversial - esp. wrt to starches / carbs, fish oil and a few other topics) book ;-)

Figure 1: Names and characteristics of eight common potato cultivars in the British diet (left) and experimentally evaluated area under the glucose curve and glycemic indices (right; data based on Henry. 2005)

If we take a look at the data in figure 1, which shows both the incremental area under the glucose curve (AUC) and the GI of eight commercially available and commonly consumed British potato cultivars, it should however be quite obvious that the concept of the bad high-GI regular potato is about as misguided as the racist or religious prejudices some of our fellow human beings are still harboring against other members of the human race. With glycemic indices that range from 56 for the "waxy" Marfona to 94 for the "firm" Maris Peer, the "bad" regular potatoes cover the exact same GI range as their "healthy" sweet cousins (come back tomorrow for Part II of this series with more information on sweet potatoes).

Cultivar, processing, serving temperature and more have profound influences on the GI

The type  (=cultivar) of the (classic) potato, is yet neither the only, nor the most important determinant of the glycemic index of a potato meal. The processing method and, to my own surprise, even the food temperature have considerable influence on the glucose response to otherwise identical test meals, as well:

Figure 2: Incremental areas under the curve (AUC) and glycemic index values for 50 g available carbohydrate portions of white bread and seven potato meals tested in a cohort of 12 healthy subjects (data adapted from Fernandes. 2005)

On the left = "better than white bread"-side of figure 2, we have cold, boiled red potatoes (GI 56.2) and, surprise, frensh fries (GI 63.6) and roasted Californian white potatoes  (GI 72.3, but lower AUC than white bread). On the right = "worse than white bread"-side, instant mashed potatoes (GI 87.7) and the hot variety of the "low GI" red potatoes (GI 89.4) are competing for the red lantern.

With regard to the unexpected differences between cold and hot red potatoes, it is important to note that the results of a 2011 study by Kinnear et al. confirm that the latter is not an artifact of the Fernandes study. In their trial, the scientists from the University of Toronto found an average GI reduction of -37% (mean GI for the tested cultivars ~47), when the freshly boiled potatoes were refrigerated at 4°C for 24–28h before they were served to the 10 healthy study participants (Kinnear. 2011). As far as the reasons for this temperature-dependence of the glycemic index is concerned, Kinnear et al. speculate that it is an effect "due to starch retrogradation", which is a process that takes place in gelatinized starch, when the amylose and amylopectin chains realign themselves and thusly causes the liquid to gel. This is quite interesting, as it stands in line with the low GI of the Marfona potato (cf. figure 1), the texture of which is described as "waxy". The long-established relation of the phosphate content and the degree of starch gelatinization (and thusly digestibility and GI), on the other hand, could explain difference between crops and differences between identical crops grown on soil with different phosphate contents.

Figure 3: Areas under the glucose curves (AUC) in 32 healthy volunteers to 50g carbohydrates from mashed potatoes with or without 10g fructose administered 0, 30 or 60min before the meal. Measure by Accu Check finger-prick glucometer and YSI glucose oxidase analyzer (data adapted from Heacock. 2002)

Did you know that fructose, of all, is able to reduce the postprandial increase in serum glucose in nondiabetic adults (mean age: 26)? In their 2002 study, Patricia M. Heacock and her colleagues were able to show that pre-ingestion of 10g of fructose 60min and 30min before the ingestion of a 50g carbohydrate meal (from potatoes) reduced the area under the glucose curve (glucose AUC; cf. figure 3) by 25% and 27%, respectively (Heacock. 2002). The immediate co-administration of 10g of fructose with the potato meal (figure 3, 0 min), on the other, did not induce any statistically significant changes in the glucose AUC of the 13 male and 19 female study participants whose blood glucose levels were measured by finger-prick capillary blood (Accu Check) and glucose oxidase analyzers (YSI).

Furthermore, a 1999 study by Soh and Brand-Miller from the University of Sidney (Soh. 1999) shows that the real-world glucose responses of different individuals to differently processed and stored potato cultivars cover an even broader spectrum (especially on the low GI side) than the results of the previously cited studies suggested. The GI values, the Australian scientists calculated based on the glucose response to a 50g carbohydrate portion of eight different potato meals (three varieties, four cooking methods, two states of maturity) differed by as much as +/- 55pts, with canned new potatoes (GI 65) at the upper and boiled Desiree potatoes (GI 10) at the very lower end of the spectrum. And as if things were not complicated enough, already, Soh and Brand-Miller also introduce yet another variable into the equation - the size of the tuber, which showed a statistically significant correlation with the glucose response of the study 10 healthy participants (correlation between GI and tuber size: r=0.83, p < 0.05).

Black-and-white thinking and ineradicable prejudices

If we base our argumentation solely on the glycemic index, which is in fact the main argument that is brought forward against "regular" potatoes in the public debate, it is quite clear that the poor (regular) potato is another victim of the human propensity to black-and-white thinking and the public's stubborn adherence to convential nutritional wisdom. With reference to the "unjustified generalization" that "all potatoes have a high glycemic index", Anette E. Buyken and Anja Kroke, two researchers from the Research Institute of Child Nutrition in Dortmund, Germany, write in their letter to the editor of the British Journal of Nutrition (Buyken. 2005):

Figure 4: GI values (glucose reference) for potatoes by different cooking methods; the horizontal bars indicate the minimal and maximal glycemic index; the dotted vertical lines mark the conventionally accepted  "low GI" <55 (left) and "high GI" >70 (right) cut-off points (the figure was taken directly from Buyken. 2005)

[...] as with all GI data, the GI values of potatoes may depend on cooking method, processing, variety and the composition of the meal. This fact deserves attention since mashed potatoes, French fries, baked potatoes and potatoes cooked in a microwave are characterised by GI values mostly exceeding the upper limit for a high GI value of 70; whereas conventionally boiled potatoes appear to have a GI value on average below 70. The values of conventionally boiled potatoes do vary considerably though, so it may also be that some potato varieties have an inherently low GI what-ever the cooking method (Najjar. 2004; Fernandes. 2005). In this context, it should be considered that most currently available GI values are based on mature potato varieties (Ontario, Prince Edward Island, Desiree, Pontiac, Sebago). The starch of more mature potatoes is, however, easier to digest, presumably due to increased amylopectin branching and hence lower resistance to gelatinisation, which in turn results in a higher GI (Soh. 1999).

Buyken and Kroke support their argument by the means of an illustration of the broad range of the glycemic responses (and respective GI) of study participants to 46 different potato meals (cf. figure 4) and emphasize that there are significant differences in both the preferred potato cultivars, as well as the respective cooking / processing methods between European and US customers. While the former "prefer potato varieties characterised by a lower GI", the prevailing potato varieties in the US are mature and exhibit significantly higher glycemic indices. This trend toward higher glycemic indices in US potato meals is reinforced by the average American's preference to fry, bake, mash, roast or microwave his potatoes, so that it would  be "thoughtless" for any European, or American who selects less mature, low GI cultivars and refrains from frying, baking, mashing, roasting or microwaving his potatoes to follow the grossly over-generalized recommendation to eat less potatoes.

Ok, not all regular potatoes are made equal, but sweet potatoes are still king, right?

Against the background that my grand father who lived a 100% healthy, diabetes-free life into his late 90s, competed in track and fields and swam laps until about 6 months before he died, had regular potatoes with every dinner, I may be somewhat biased as far as the "bad potatoes" are concerned. This does yet not compromise the value of the rational arguments and scientific evidence against the unjust and, above all, over-generalized vilification of regular potatoes I have brought forward in this first installment of the Potato Manifesto. If you are interested in how the "holy" sweet potato which is currently hailed as the savior of the neo-paleolithic race compares, come back tomorrow for Part II of the Potato Manifesto ;-)

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 ;-)

References:

• 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.

Natural Resistant Starch Reduces Body Fat & Weight Gain in Obesity Prone & Lean Rodents. 8% RS2 Necessary for Weight Loss Effect, Only 4% for Increases in GLP-1 and PYY

Potatoes! I don't suggest you eat them raw, but if you did they would make a good source of resistant starch. You don't eat potatoes at all? Read the Potato Manifesto and learn why regular potatoes are not as black as they are portrait!

I guess, you will remember my post on WM-HDP from back in the day. As usual you, as a SuppVersity reader were in the know, way before the ThermiCarbs and its identical clones hit the supplement market. It has however gotten relatively quiet around these purported super starches, which bypass enzymatic breakdown in the small intestine and get converted to short-chain fatty acids (SFCA) in the colon. Why? Well, my best bet is that people expected some sweet junk of which they could eat as much as they wanted with the only side effect being increased muscularity and decreased body fat levels. I am well aware that you knew better than that, but you know how people are: Always on the look-out for the magc pill... or in this case, the magic starch ;-)

Cutting fat by eating more: The old adage of the "fat burning foods"

Be that as it may, a soon to be published study by researchers from the Commonwealth Scientific & Industrial Research Organization in Australia confirms: If you exchange a high enough amount of regular carbohydrates with resistant starches (even regular ones, lower resistance to enzymatic breakdown that WM-HPD), this can be a viable tool to shed some body fat.

Unfortunately, though, the results of the very this study do also suggest that the effectiveness of this regimen will largely depend on (a) your phenotype and (b) your willingness to follow your hopefully not totally messed up satiety response and decrease your caloric intake voluntarily, just as the male Sprague-Dawley, the 'subjects in this study by Belobrajdic, King, Christophersen and Bird.

Figure 1: Energy intake and final body weight (left) and relative changes in fat mass and total liver weight after 6 weeks on diets with different resistant starch content (based on data from Belobrajdic. 2012)

Both (a) and (b) could however be major caveats when it comes to the practical realization of similar results in human beings, to whom I would not suggest that they follow a standardized diet with ~15% fat, 19% protein and ~66% carbohydrate, either - regardless of whether they exchange 0%, 4%, 8%, 12% and 16% of the mostly high GI carbs in their diets by resistant starch or not (the values are relative to the weight of the chow).

Just as raw potatoes, green bananas contain RS-2, the natural form of fermentable resistant starch. When you cook them, the RS2 content is continuously reduced.

Note: The "2" in "RS2", indicates that RS2 is, contrary to WM-HDP, which belongs to the "RS4" variety of resistant starches, a naturally occurring molecule. And though this is the case for WM-HDP vs. high amylase maize starch, the latter does not necessarily mean that one is more resistant to enzymatic breakdown than the other. You could for example think of special applications, where you want to have a starch that of which roughly 75% will be broken down into glucose in the small intestine, while the other 25% are fermented further down in the large intestine. This would be a synthetic molecule and therefore categorized as RS4, but still relatively easily "digested".

What I consider especially problematic, though is the fact that people who like to eat, let alone those, who use food as a, if not the only way to experience pleasure in their lives (eating for reward), are going to have a very hard time to satisfy their cravings with this blatant "food". I mean, we all know that "satiety" is not really an issue for most people with weight problems, so it remains questionable to which degree those who actually need a crouch like this will eventually benefit from a resistant starch which exerts its fat loss effect in rodent experiments at least partly via dose-dependent decreases in food intake -- 3%, 6%, 9% and 11% in the 4%, 8%, 12% and 16% resistant starch groups, respectively.

Ok, I have to admit there is more to it than just eating less

Figure 2: For the lean rodents, body weight gain and feed efficacy (weight gain per gram of chow) favor different "optimal" RS2 levels.

Allegedly, the reduction in food intake alone cannot explain the decrease in weight gain in either the obese or lean rodents, but if you take a closer look at the data I plotted in figure 2, it does still become obvious that  the ameliorative effects weight gain in the obesity resistant (i.e. naturally lean) rodents don't obey the "more is more" rule, as the scientists would have it in their abstract:

"Obesity prone rats (OB) gained less weight with 4, 12 and 16% RS compared to 0% RS, but the effect in obesity resistant [lean] animals was significant only at 16% RS. Irrespective of phenotype, diets  containing ≥8% RS reduced adiposity compared to 0% RS. Energy intake decreased by 9.8 kJ/d for every 4% increase in RS. [...] Insulin sensitivity was not affected by RS." (Belobrajdic. 2012)

In the naturally lean animals, the "optimal", i.e. the lowest feed efficacy would be achieved with 8% of RS2 in the chow and not as the "≥8% RS" implies with 16% of resistant starch in the diet.

Ok, I have to admit there is more to it than "minimal feed efficiency"

In the scientists defense, it must however be mentioned that the plasma lipid and gut / satiety regulating hormone levels they measured did in fact show an almost linear increase with the amount of fermentable resistant starch in the diets (see figure 3). Since Belobrajdic et al. do not provide individual data from the two groups, but settle for a table that will tell you that there were no treatment x group interactions  (this means that the outcome was not different for obesity resistant and prone animals) and a phenotype interaction with the overall outcome was only present for leptin, there is no way to tell for sure.

Figure 3: Inter-group comparison (not differentiated for lean vs. obese, because there were no significant interactions, except for leptin) of plasma lipid and gut derived hormone levels (data adapted from Belobrajdic. 2012)

So, with all these "admission" (as in "I have to admit..."), I have to admit *lol* that using high-amyolse starch as a part of your contest prep, maybe to bake pancakes or use it in another food, where the "taste" does not matter that much is could in fact be a viable dietary tool. It won't get you stage ready on its own, though and has one major caveat I have not even mentioned yet: You better make sure you always know where the next clean toilette is. Assuming that those 16% RS2 have the same effect on the volume of your feces as they had on that of the rodents in the study at hand, you may be spending 5-times more time on the loo thhan usually ;-)

If you can't remember what WM-HDP was, click on the image to go back to the article. Regardless of whether you pick up a natural or an artificial starch, this stuff is not "zero calories"! The high amylose maize starch in the study at hand has 10.45kJ (WM-HDP should be similar), i.e. 2.5kcal/g you will have to make up for by cutting out real foods.

Bottom line: Assuming that the results from the study at hand translate to human beings the incorporation of resistant starches in your diet seems - at least to a degree at which your bowel can handle it - to entail a lot of health benefits. The problem I see, is that you will have to force down these empty calories instead of eating healthy foods if you want to benefit.

If you simply add resistant starches (natural or artificial) to your diet, without cutting back on calories, elsewhere, you will become fatter, not leaner.

You will also have to take into account that adding resistant starch to the high sucrose diet of the rodents in this study will necessarily entail greater benefits than exchanging some tubers, rice, fruit and other non-sugary carbohydrate sources from a healthy diet with resistant starch powder - not to speak of all the beneficial micro-nutrients you will be missing!

References:

• Belobrajdic DP, King RA, Christophersen CT, Bird AR. Dietary resistant starch dose-dependently reduces adiposity in obesity-prone and obesity-resistant male rats. Nutr Metab (Lond). 2012 Oct 25;9(1):93.

Eat More, Burn More and Lose Fat Like on Crack with GLP-1!? Roux-en-y Bypass Study Sheds a Whole New Light on Satiety(Hormone)-Induced Weight Loss

Image 1: A gastric bypass should always be the last option; with all the possible complications it is nothing to treat lightly (img medcenterone.com)

Everyone who has read the Intermittent Thoughts on "Goal Setting and Programming Success" with the three somatypes, SuperSize Homer, Peter Griffin and Anorexic Stan, will be aware that I do acknowledge the oftentimes life-saving benefits of surgical anti-obesity interventions, when everything else fails. Until recently, I did however assume that"cutting off" a part of your stomach or using a sling or other devices to reduce its size would simply reduce a patients ability to overeat, thusly reduce hi caloric intake and help him to cut his weight back into a region that is no longer life-threatening. The recent publication of a study by scientists from the Harvard Medical School (Nestoridi. 2012) does yet suggest that the effects of roux-en-y gastric bypasses are in fact way more far reaching than, at least I, had previously thought.

Does a roux-en-y bypass "actively" burn fat!?

In their experiment Erini Nestoridi and her colleagues had observed that the overweight mice in the active arm of their study, i.e. those mice who were not just cut open (sham group), but had also received the roux-en-y gastric bypass (RYGB), did not only lose body fat like crazy, they did also consume significantly more calories, expended significantly more oxygen (a marker of fatty acid oxidation), had a significantly lower respiratory quotient (=burned more fat than glucose for fuel) and wasted almost twice as much energy in the form of body heat than their sham-operated peers, so that their overall energy balance looks like they were on DNP or any other "true" thermogenic fat burner (cf. figure 1)

Figure 1: Energy intake, respiratory quotient (higher levels = more glucose, less fatty acid oxidation), heat production, fat free mass and fat mass during and at the end of the 8-week intervention trial subsequent to either sham or roux-en-y gastric bypass operations on obese mice (data calculated based on Nestoridi. 2012)

In combination with the to-be-expected increase in fecal energy loss (44kcal/day vs. 13kcal/day), which occurred as a consequence of the decreased transit time and ability to absorb nutrients from the chow, these changes explain very well, why, at the end of the 8-week intervention period, the RYGB mice had lost all their unhealthy fat depots, while their sham operated had gained another 6g of body weight.

Gastric bypasses increase the GLP-1 response and thusly restore metabolic health

All that reminded me of some research with regard to the metabolic role of the so-called satiety hormones, CKK, PYY and above all GLP-1 I have been doing as of late. Glucagon-like-peptide 1 (GLP-1), in particular, exerts profound and far reaching metabolic effects, which have little to do with the satiety function its label "satiety hormone" does imply. Interestingly, the restoration of normal fasting blood glucose levels, the  normalization of the glucose response to an oral glucose tolerance test, the increased fatty acid oxidation and even the RYBG mice' profoundly reduced preference of the hypercaloric high fat chow (after the surgery the rodents had free access to normal and the highly palatable "high fat" chow, on which they had accumulated a 50% body fat percentage before the surgery) have all been associated with increases in GLP-1 levels in previous studies. In their 2005 review of the literature, Burcellini et al. even mention the involvement of cerebral GLP-1 in cognition and memory (Burcelin. 2005).

A 2012 case-report in which Myint et al. (Myint. 2012) describe a RYBG patient who suffered from recurrent episodes of hypo(=low)glycemia due to increased GLP-1 levels would support my hypothesis that GLP-1, or rather its increased expression subsequent to gastric bypass operations could be the root cause of all the beneficial metabolic effects in the rodent study at hand and the thousands of human beings whose lives have been saved by this surgical intervention, as of yet. That this is not just a transient or outlier effect, but something we see across the board in all RYGB patients and which remains, even at a10-year follow-up has been confirmed by Mohamad S. Dar and his colleagues from the East Carolina University, who examined the GLP-1 response to oral meal consumption in 5 RYGB patients 10 years after the operation and found that the "exaggerated GLP-1 response [is] maintained [...] despite statistically significant
weight loss".

The fat burning effect of eating to satiety

Image 2: Adelfo's progress during his contest prep are an excellent example for the highly desirable "side effects" of eating to satiety.

Now, it would not only be plain out stupid to get a gastric bypass done, when that is not medicinally necessary, it would also compromise the value of "my" hypothesis that GLP-1 could in fact be the main working mechanism behing RYGB induced weight loss, if it was not (a) increased / higher in the billions of people who do not get obese in the first place and if there were not (b) other most prominently dietary means to increase GLP-1 which trigger similar beneficial metabolic effects. As you may imagine, I would not have proposed this hypothesis, if I had not already come across pertinent research, such as a 2006 study by Nicola Pannacciulli et al. in which the NIH researchers found a statistically significant association between GLP-1 levels and resting energy expenditure in 46 glucose tolerant male and female subjects with BMIs ranging from 18.6-50m²/kg (Pannacciulli. 2006).

A preliminary GLP-1 cheat sheet for the obese and non-obese dieter

The following list of dietary GLP-1 "agonists" is yet still "work in progress" and more of a preview on a future, comprehensive blogposts of the role of the metabolic function of the incretin hormones, I am currently working on (whenever I have 1s of time to spare ;-):

• short chain fatty acids (Tulhurst. 2012) 
• fermentable fiber (Greenway. 2007)
• fermentable resistant starches (Zhou. 2008)
• bile acid (Katsuma. 2005; Parker. 2012)
• egg and meat hydrosolates (Cordier-Bussat. 1998)
• milk proteins (Hall. 2003; Juvonen. 2011)
• fish oil (only if administered interperitoneal; Motoshita. 2008)
• fats, when added to starchy carbs (e.g. Frost. 2003)

Unfortunately, things can become quite confusing, because despite all those "starches" and "fibers" in the list, there are studies, which report the exact opposite effects for some of the classic dietary fibers, like psyllium, for example (Karhunen. 2010). Conflicting results by Wang et al. who report 2x increased GLP-1 levels in response to psyllium or sugarcane fiber enriched high fat diets (Wang. 2007), do thusly raise the question if the GLP-1 response is either (a) species-specific (the Wang study was done on mice), (b) depends on the accompanying nutrients (both studies used rather high fat foods / chow, though), or whether (c) the difference is a simple consequence of the study design, i.e. acute (Karhunen) vs. chronic (Wang) ingestion of fiber-(en)rich(ed) food / chow.

Could it not be about insulin, but about GLP-1?

And although we certainly cannot rule out (a) completely and must acknowledge that (b), i.e. man vs. mouse, will always make a difference, I personally believe that overall (c), i.e. the differences between the acute, the longer term and the chronic effects are, are most likely responsible for the differences in GLP-1 response and the ensuing metabolic effects. After all, fermentable fiber, fermentable resistant starches and psyllium all increase the production of short chain fatty acids in the colon. The beneficial effects the latter have on the amount of GLP-1 that is released will however arise at a very late stage of the digestion process. the decrease in GLP-1 Karhunen et al. report in their study, on the other hand, was measured right after the ingestion of the meal.

Don't forget: In non-insulin resistant individuals, glucose, or rather its transportation via the GLUT-2 receptors is a stimulator of GLP-1 release, as well. It is thusly not really surprising that Lee et al. have recently been able to show that its release is impaired in diabetic rats (Lee. 2012). With an intact GIP response (cf. WMHDP article for more on how GIP is making you fat) diabetics and most likely also "just insulin resistant" individuals are thusly getting all the negative without any of the beneficial effects of carbohydrate ingestion, so that GLP-1 is yet another piece in the "why low-to-no-carb works / may even be necessary for obese diabetics, but is unnecessary for healthy individuals" puzzle, I've been putting together with a whole host of posts over the past couple of weeks.

Given GLP-1's role as a mediator of glucose disposal and fatty acid metabolism, it is thus likely that the long-term health benefits I have hinted at in the context of the gastric bypass study, arise only when we have a steady "elevation" or rather steadily high-normal levels of GLP-1, instead of some punctuated spikes, as Karhunen observed them for "non-fibrous" foodstuff or Juvonen for low viscosity foods (Juvonen. 2009).

If we also take into account that Cheong et al. report that large fluctuations in blood glucose levels exert greater ER stress on rat insolinoma cells than chronic hyperglycemia and that the former, i.e.the large blood sugar fluctuations, yet not chronic hyperglycemia downregulate the GLP-1 receptor expression (which would induce a metablic state we would have to label "GLP-1 resistance") on these cells (Cheong. 2011). We could go as far as to speculate that the ups and downs of the glucagon-like-polypeptide 1 and the subsequent down-regulation of its receptors at the cellular level and not our contemporary scapegoat, insulin, could be at the heart of the diabesity epidemic... but I will get deeper into that in the upcoming incretin hormone special, so stay tuned!

Challenging the Special K Challenge: Especially Convenient or Especially Stupid 14-Day Weight Loss "Solution"?

Image 1: Is this really all it takes to lose those unhealthy and unaesthetic pounds? Two servings of a breakfast cereal a day, instead of two of your regular meals? Sounds too "good" (?) to be true, right? A study says it works, but only the SuppVersity will tell you the real costs!

For me, as a German, it is quite surprising that the words "Special K", or rather the reference to the eponymous product comes up pretty often in the health and nutrition blogosphere, when someone wants to point out an e-special-ly (K) unhealthy breakfast. While "low fat", still looms large here in Germany and "diet"-this and "diet"-that stickers (respective products usually carry the label "light", which shall obviously imply "light" as in "lightweight") are attached to an ever-growing number of products in the mainstream supermarkets, my fellow countrymen (I am unfortunately not so sure about the women, though) must yet have had advanced access to the data (not just the abstract - but more about that later) of Patricia K. Shaw's master thesis (Shaw. 2011), which has been peer-reviewed and published only recently, and are thusly mostly avoiding this "healthy whole grain" product from a company with a >13b revenue in 2010.

"Special K Challenge" - What does it challenge? Weight loss or yo-yo-effect?

In the respective 14-day intervention trial 24 subjects (12 men and 12 women) with a mean age of 34.7 years and a pretty chubby physique (BMI 28.6 kg/m², but body fat 28.8% and 40.7% for men and women, respectively) had to follow the "Special K Challenge" (official website), the central idea of which is that you are going to lose weight and get healthier if you replace two of your regular meals by a predefined amount of yummy (and nutritious *rofl*) expensive cornflakes, ah... I mean "Special K"...

Figure 1: Macronutrient composition of the 174kcal Special  K + skim milk "meal replacement" and the Special K Snack Bars (83kcal) and Mini Breaks (99kcal) the participants consumed during the 14-day challenge and the consequent reductions in protein and fat intake relative to baseline (data calculated based on Shaw. 2011)

In view of the fact that everyone appears to be on the lookout for an easy and above all convenient way to lose weight, it was not difficult for Mrs. Shaw to recruit their subjects among the faculty staff and senior students from the University of Limerick, who actually had to do nothing, but adhere to these two "protocols" for 2x14 days:

1. Control phase: Do what you usually do and eat what you usually eat for two weeks, log all your foods and get back to the lab to get another body weight, body water, body fat, lean body mass (the latter two via DXA scans), waist and hip circumference measurement taken.
    
2. Special K Challenge: Keep doing what you usually do, keep eating what you usually eat, but replace 2 of your main dishes with Special K + semi skimmed milk and eat fruit and/or Special K Mini Breaks or Special K Snack Bars between meals (cf. figure 1), log everything you eat and return your hopefully lighter self as well as the logs to the lab in another two weeks.

About as convenient as the average pizza-ordering slacker likes it, right? It is thusly not really surprising that the overall compliance of 83% was above what you usually see in dietary interventions.

"I want my pizza back!"- and "I better completely stop eating to maximize weight loss"-effect

What is similarly unsurprising, is that the overall calorie intake is reduced (avg. energy deficit: 673kcal/day) by a "challenge" , in the course of which two of the main meals (of which most people obviously consume only three) are replaced with a 174kcal "meal replacement" in form of yummy cornflakes with watery skim milk (aside from the "bah, I want my pizza"-effect, I am thinking about the "hyperpalatability hypothesis" here, as well; cf. Guyenet. 2011). That it is so profoundly reduced that at least one male subject had a caloric deficit of 1555kcal per day (!), however, clearly suggests that the end-result of this type of "diet" (or shall we call it a hunger-strike?) is not going to work. It is thus all the more surprising, that, according to the conclusion of the abstract, ...

The results of the present study demonstrate that the Special K Challenge was effective in reducing total energy intake and resulted in a positive, health-related change in body composition. The reduction in total body mass, regional fat mass and waist circumference may act as an effective motivator to long term body mass reduction.

Certainly worth taking a closer look at the data, right? Well, for the first point, i.e. "effective in reducing total energy intake", we already know that this is true. "Effective", by the way, is effectively understated. Now, what about the "positive, health-related change in body composition"? What would that imply? A reduction in body fat and an increase in lean mass, right! And what have we got?

Figure 2: Lean mass and fat mass of 24 overweight  men and women before 2-week accommodation phase (pre) and before (basal) and after (Special K) 14-day "Special K Challenge" (data adapted from Shaw. 2011)

We got a reduction in body fat and a reduction in lean mass - and worst of all, the female study participants, who, with their 40%+ body fat levels already had no muscle to begin with, lost almost twice as much lean mass as body mass. Assuming that they are "scale watchers" (and should read the "How to track your progress on a diet & exercise regimen"), this may in fact have been an "effective motivator", but it is also a profound obstacle to the "long term body mass reduction", unless we want to define that as "starving your muscles away".

"But it does work! So what do you want?"

Even if you are not effected by it yourself, I bet that everyone of you knows someone who has maybe not even gained weight, but has become fatter and fatter with every diet he (or presumably "she") has "done". This study on the "Special K Challenge" shows you exactly what went wrong for him/her/them:

Image 2: Although common wisdom would say so, eating salad is no alternative either... when I come to think about it, it may be an alternative to eating toilette paper, but that won't help with fat (not just weight!) loss either.

• believing in the existence of a "quick fix" and/or "convenient solution" that will work in 1-2 months, let alone weeks and thusly
• going on a diet instead of changing your diet as part of changing your lifestyle 
• not meeting your minimal energy requirements / starving yourself
• not having enough protein and fat with EVERY meal
• snacking, in general, and on processed foods, in particular
• no exercise (in this case), or tons of endurance exercise to exercise your "cheats" away
• using the scale as a measure of success

Taken together, all that programs failure, no matter how "motivating" it may be... or do you really believe the guy with the -1,500kcal/day deficit or his female counterpart with -1,139kcal/day will "stick" to this "diet" for longer than two weeks? I don't! And we both know what happens, when they are sitting with their friends and family at the coffee, next Sunday, right? ... I guess, it is thus unnecessary that I answer the question I raised in the headline, explicitly - Especially Convenient or Especially Stupid? You decide!