Saturday, September 10, 2011

Zone Out

Neil Mann belongs to the team of researchers who work with Loren Cordain and promote high intakes of lean meat on an evolutionary basis.

For example, he authored Dietary lean red meat and human evolution in which he argues that various lines of study "indicate the reliance on meat intake as a major energy source by pre-agricultural humans."

Mann and another team from Royal Melbourne Institute of Technology published a new study of the efficacy of a high (30%) protein diet, in comparison to a high (55%) carbohydrate diet, for type 2 diabetes.

The effect of high-protein, low-carbohydrate diets in the treatment of type 2 diabetes: a 12 month randomised controlled trial.

In this study, 99 subjects received advice to follow low-fat (30% total energy) diets; 53 of those received instructions to eat a diet supplying 30% of total energy from protein and 40% from carbohydrate (high protein arm), while  46 received instructions to eat a diet supplying 55% of total energy from carbohydrate and 15% from protein.   

The high-protein diet had the same proportions of protein, fat, and carbohydrate (30:30:40) recommended by Barry Sears in his "Zone" diet books.  Supposedly this proportion produces better blood sugar and insulin control than a high carbohydrate, lower protein diet.

The aim was to find out if eating a diet high in protein would provide superior glycemic control to a diet high in carbohydrate, so the primary endpoint was change in HbA(1c).  "Secondary endpoints included changes in weight, lipids, blood pressure, renal function and calcium loss."

The results?

"HbA(1c) decreased in both groups over time, with no significant difference between groups (mean difference of the change at 12 months; 0.04 [95% CI -0.37, 0.46]; p = 0.44). Both groups also demonstrated decreases over time in weight, serum triacylglycerol and total cholesterol, and increases in HDL-cholesterol. No differences in blood pressure, renal function or calcium loss were seen."

Mann et al concluded:

"These results suggest that there is no superior long-term metabolic benefit of a high-protein diet over a high-carbohydrate in the management of type 2 diabetes."

I don't have access to the full text, but since the team that did this study includes Neil Mann, one of the strongest proponents of the idea that humans are adapted to diets high in animal protein, who might have a bias in favor of high-protein diets, this study appears to undermine the high-protein approach to diabetes.

It doesn't appear to do the Zone Diet any favors either. 

On the other hand, it supports the already established body of literature showing efficacy of a high-carbohydrate approach to diabetes type 2.   The high-carbohydrate diet apparently produced meaningful decreases in weight, HbA(1c), triglycerides, and total cholesterol, and increases in HDL.

The decrease in trigs and elevation of HDL are particularly of interest, since very often I see claims that high carb diets raise trigs and lower HDL. 

This study provides evidence against the claim that humans are specially, evolutionarily adapted to high-protein diets and maladapted to high-carbohydrate diets, and undermines the claim that this one disease of civilization, type 2 diabetes, and its chief feature, hyperinsulinemia, arise from high-carbohydrate diets. 

Of interest, both diets had relatively low fat contents.  Since altering the ratio of protein and carbohydrate appeared to have no effect on results, this study may also suggest that reduction of dietary fat proportion plays a key role in the treatment of type 2 diabetes if the goals are reduction of body mass, HbA(1c), triglycerides, and total cholesterol, along with increases of HDL.


Exceptionally Brash said...

While I have not read this entire study either, on the surface, it certainly does not look like it is any kind of "proof" you seek. This is a study that compares two methods to manage diabetes, and offers not a shred of insight as to how people got that way.

Alan said...

What is your reaction to the claim that protein provides the most satiation per calorie?

Paleodoc said...

That you are prepared to comment and venture conclusions about this research on the basis of a minimally informative abstract, speaks volumes about your current personal biases. There was no low carb group (based on any reasonable deinition of the term) in this study. On the basis of the information offered in the abstract, any objective observer would resist the temptation to comment. I look forward to reading the paper in full.

Jeff Consiglio said...

Ah yes...The Zone Diet. Followed it way back in a period we now refer to as "The Mid-90s" - a simpler time for sure. I cringe at the memory of my dumb-self mixing up a precise 40/30/30 mixture of apple juice, protein powder and canola oil in a blender then chugging it. Gave me horrible hypoglycemic-attacks. Didn't exactly taste good either. But hey...I was in the Zone Baby!

Kikilula said...

Perhaps there was a positiv effect on the insulin secreting beta cells b/c of a reduction of linoleic acids through those low fat diets?

Peter said...

Don, couple of things. 30& of fat is not "low-fat" by any stretch. Low-fat is something that comes naturally when one is eating whole-food vegan fare (without oils). Kind a diet people in rural parts of Asia, Central-Africa and parts of South-America eat. This diet will give fat digits around 10%. Whole-food vegan diet without oils, the diet promoted by Esselstyn, Ornish, McDougall, Campbell, Barnard, etc.

The "30% low-fat"-religion started thanks to the 1982 report of National academic of sciences. The initial plan was to recommend even lower fat intake, but the business didn't like it, since going even further down from the 30% would in practise mean that one have to cut the amount of animal-derived foods (see The China Study).

Campbell shows in his book that one can construct "low-fat" meals which gives you significant higher cholesterol and animal protein amounts as opposed to higher-fat diets (and no, the cholesterol-thingy is not debunked, see "GI" Jenkins thoughts on the issue, and the chief of American Journal of Cardiology giving his thoughts on the optimal diet for humans,

Anyways, here's some clinical evidence of how actual low-fat diets work with diabetes.

Scientist at the Pritikin got staggering results with their pilot study. Out of 25 patients, 24 were off from the medication within three weeks with ultra-high carb diet. Reknown diabetic scholar Anderson did pretty much the same. In his pilot study, out of the 40 patients 36 were could stop the medication within weeks while being exposed to moderate excersise and high-carb vegetarian diet. Moreover, In Anderson's study diabetic 1's could lower their medication on average 40% with ultra-high veg diets.

“Ideally, diets providing 70% of calories as carbohydrate and up to 70gm fiber daily offer the greatest health benefits for individual with diabetes”.

Dr Anderson, MD

Anderson JW. “Dietary fiber in nutrition management of diabetes” In: G. Vahouny, V. and D. Kritschevsky (eds.), Dietary Fiber: basic and clinical aspect, pp. 343-360. New York Plenum Press, 1986

Barnard RJ et al. “Response of non-insulin-dependent to an intensive program of diet and excersise”. Diabetes Care 5 (1982): 370-374

Anderson JW, et al. “Dietary fiber and diabetes: a comprehensive review and practical application”. J Am. Diet. assoc. 87 (1987)

“Medical research confirms that up to 50% of people with Type 2 diabetes can eliminate diabetes risk and discontinue medication within three weeks by adopting a low-fat, plant food diet and regular daily excersise”.

American Journal of Clinical Nutrition, 1979

And here's the landmark study: when the amount of carbs (refined ones in this study) was increased from 45% to 85% (in practice it meant shift to whole-vegan diet, without oils or avocados) the condition of diabetic enhanced in every measurable way. The researchers concluded the following:

"An extremely high carbohydrate-fat ratio improves insulin sensitivity whereas more moderate changes (40-60% carbohydrate) produce less convincing results"

Smith U. Carbohydrates, fat, and insulin action. Am J Clin Nutr. 1994 Mar;59(3 Suppl):686S-689S.

Here's something to worth check as well.

"High-carbohydrate, high-fiber diets increase peripheral insulin sensitivity in healthy young and old adults"
Fukagawa NK et al.

American Journal of Clinical Nutrition, Vol 52, 524-528, 1990

"Improved Glucose Tolerance with High Carbohydrate Feeding in Mild Diabetes". John D. Brunzell et al

N Engl J Med 1971; 284:521-524March 11, 1971

Matt Schoeneberger MS said...


The first paragraph of page 739 is interesting to me, where the authors discuss the possible different outcomes of controlled-feeding studies and standard dietary counseling. In essence, their questioning whether high protein diets are more effective, but that adherence to such a diet may be low.

Have you read the controlled-feeding studies they point to? If so, what do you think?


Jimmy Gee said...

"This study provides evidence against the claim that humans are specially, evolutionarily adapted to high-protein diets and maladapted to high-carbohydrate diets, and undermines the claim that this one disease of civilization, type 2 diabetes, and its chief feature, hyperinsulinemia, arise from high-carbohydrate diets. "

Not sure I see this conclusion. The abstract does not provide actual raw data to review, so it's hard to truly evaluate these results. I also would question if the change in carbs was a true change. Without actual numbers, percentages can be very misleading.

Don said...

Exceptionally brash,

I don't see anywhere that I used the word 'proof.' I simply said that the results given in the abstract don't support the idea that carbs cause diabetes, since the high carb diet was successful as management for diabetes.


Who eats 'protein'? Most often, we eat various foods. Satiation studies that I have read tend to favor high carb foods as most satiating per kcalorie.

Exceptionally Brash said...

@Don, that's why "proof" was in quotes. I know you didn't regard it as all that firm.

I think many of us during the latest smackdowns/controversies are making an assumption that we can just dig our way out of a mess by doing the opposite of what we think led us in.

I don't operate under that assumption.

kyle said...

Had a good thought, I think.

I was eating oatmeal for breakfast and I got to thinking about how whole grains are good for your heart and what not, so they claim. Thats perfectly fine, but I remember my Aunt trying to tell me rice is really bad for you. Basically, my point is why are whole grains a life saver and rice so bad for you. I have people tell me rice is so bad for me. I eat white rice and I'm just thinking what is the rationale that whole grains can save lives and rice is going to kill you. Personally, I came to the conclusion that the government wants us eating more whole grains because we can't compete competitively with Asian producers. Atleast, thats my conspiracy theory. Its not a serious thing bothering me, just a thought I entertained for a moment and couldn't find a reasonable conclusion. Just wanted to hear your thoughts on this Don.

Don said...


Why should I not comment on a published abstract? As for venturing conclusions, I simply stated that the info in the abstract doesn't support the idea that a 30% protein diet is more effective than a 15% protein diet for managing diabetes type 2, nor does it support the idea that high carb diets promote diabetes.

Despite lacking the full text, I commented because it is a paper by a 'paleodiet' advocate who apparently found that a supposedly paleodiet macronutrient ratio (~30% protein) did not perform any better than a supposedly non-paleodiet macronutrient ratio.

Anyway, thanks to Matt Schoeneberger from SPEED Weight Loss I finally did get a copy of the full text, and nothing in it changes the data presented in the abstract substantially. The high protein group managed to get their protein up to 28% and their carbs down to 40% at 3 months. Both groups got their fat to 30% at 3 months. The high carb group got their carbs up to 48-49% from a baseline of 46%, but they didn't get their protein down to 15% at any measured time point.

At 12 months, the high protein group was at 27:31:42 and the low protein group at 19:32:48. The high protein group was consuming 42% more protein than the other group, and the high carb group was consuming 14 % more carbohydrate than the other. The HP group accomplished a 25% energy restriction, and the HC group a 28% energy restriction. This doesn't support HP being more satiating or enabling a greater energy restriction.

The main failure was in getting the HC group up to 55% carbs and down to 15% protein. This probably occurred because to get protein down to ~15%, most people have to limit animal products more than they think. If they don't reduce animal products enough, increasing carbohydrate-rich foods keeps protein higher because carb-rich foods also supply protein.

The authors wrote: "One interesting finding from this study was that the degree of energy reduction, not the composition of the diet, was related to the long-term improvement in glycaemic
control. Although these results should be interpreted marginally in light of the multiple testing, this finding suggests that dietary approaches should focus more on
limiting energy intake rather than modifying the consumption
of specific macronutrients."

This study is simply consistent with dozens of others that have found similar outcomes...and that is also why I felt confident to comment on it.

Don said...


I think that reducing fat helps because it helps reduce energy intake and this reduces build up of unmetabolized fat (and sugar) in cells, which reduces insulin resistance. IT simply reduces the excess nutrient input that clogs up the metabolic machinery.

Don said...


You don't have to convince me that a reduction of fat and increase of carbohydrate will assist in diabetes. I am very familiar with the work of Anderson, etc. as you mentioned.

I didn't call the diets "low fat" I said they had relatively low fat contents...relative to some other diets. If a diet is 70% non-fat, I consider it low in fat. Would you call it high in fat?

Of course you can go lower, and I know there is plenty of reason to suspect that lower in more therapeutic for some conditions.

Don said...


don't have access to the full text of the first one they cite, but the abstract:

The second one has some interesting findings. First, the high protein diet produced a higher fasting insulin and a greater insulin response after the late day meal:

"The mean fasting serum insulin concentrations were 104 ± 18 pmol/L (17.3 ± 3.0 µU/mL) and 110 ± 21 pmol/L (18.4 ± 3.5 µU/mL) after the control and high-protein diets, respectively (Figure 4). The insulin concentrations increased rapidly after the meals, as expected. The insulin excursion was not significantly different with either diet after breakfast and lunch but was modestly greater after dinner with the high-protein diet. "

It was this INCREASE in insulin levels to which they attributed the lower serum glucose in the 30% protein group. In other words, the HP group had somewhat lower fasting glucose because they had higher insulin. Just the opposite of the claims made by some HP diet advocates that a HP diet will lower insulin.

I don't see why Mann et al would question the ability of people to follow their 30%P, 30%C, 40%F diet Rx, since in this study, the HP group came closer to the Rx than the HC group. If I had written the discussion, I would have wondered why I failed to get the HC, 15%P group to get their protein intake down to the Rx.

Don said...

Jimmy Gee,

OK, I should have written: "Based on this abstract, this study appears to provide evidence against the claim & etc..."

Although I agree that the abstract may misrepresent the contents of articles in some cases, I have found that in general, the abstract is a reliable report of the contents of the full study. I give the authors the benefit of the doubt...innocent until proven guilty. And, having now read the full study, I still agree with my conclusion...this study doesn't support the idea that humans do better on high protein than on high carb diets.

Peter said...

Sounds good Don. You have an important task which involves guiding the religious Low-Carb sect out of intellectual despair.

BTW did you see this one that just came out!

"Type of Vegetarian Diet, Body Weight, and Prevalence of Type 2 Diabetes"

Since vegans were best off in every way (diabetes risk, BMI) the authors concluded that risk of diabetes goes hand in hand with prevalance of animal foods in diet.

Jimmy Gee said...


Really my thought was around the use of percentages in evaluating or comparing different diet composition across different groups of people. Percentages can mislead in absence of the actual data. I am at a disadvantage, not having the full article, so I cannot comment on how relevant the reported statistical significance is compared to common sense. Statistical significance is not always meaningful to real world. It would be best to have the actual data and graphical summary to put with the stats to help judge just how meaningful the results are.

Matt Schoeneberger MS said...

Don said:

"It was this INCREASE in insulin levels to which they attributed the lower serum glucose in the 30% protein group. In other words, the HP group had somewhat lower fasting glucose because they had higher insulin. Just the opposite of the claims made by some HP diet advocates that a HP diet will lower insulin."

I see your point, although I'm not sure those HP advocates would recommend consuming 223 grams CHO (193 net CHO) per day, or consuming those CHO from Raisin Bran, potato chips, Saltines and drinking 4 cups of skim milk per day.

Don said...


Perhaps. But as the authors state, they and others have shown that consuming protein and carbs together increases insulin response...this was the reason for creating post-training shakes that included both, to increase insulin secretion for better glycogen storage and increased protein synthesis.

The HP menu lists 6 g of saltines, 28 g (1 oz) potato chips, and 1 oz of Raisin Bran. The LP menu has a 65 g bagel instead of the 6 g saltines, the same 1 oz of potato chips and Raisin Bran as the HP menu, plus 8 oz grapefruit juice, 1 tsp sugar, 43 g of graham crackers, a 100% larger baked potato, 2 slices of cracked wheat toast, and several fruit servings not in the HP menu. The total carb and refined carb intake is higher on the LP menu, yet it still produced a lower fasting insulin level than the HP diet.

They did their best to compare apples to apples (similar foods in each menu, but different serving sizes.

The LP diet also had 276 net g of carbs, 50% more than the HP diet.

Since milk is more insulinogenic than some other foods, the high skim milk intake on the HP plan may have played a role in the higher insulin on the HP plan, but again, the combination of protein and carbs has been repeatedly shown to produce more insulin than carbs alone.

Strontium Pup said...

The thing I don't understand is how a study showing little difference between two diets with roughly the same fat content, can be evidence in support of the proposition that dietary fat may be of importance.

Taylor said...

Geoff Bond of agrees with you as does Cordain.

Duke of Earls said...

I don't think one will find some miracle macronutrient proportion for health, or, in this case, diabetes management. As an omnivorous species with a worlwide distribution, genetic variation has 'blessed' us with pointed differences in how we metabolize food. What works for one person may not work for another. Some, whose ancestors have been growing rice for ten thousand years, will do well with high-carb... Others, whose ancestors had no interaction with grains of any kind until the past 400... Will obviously be less adapted. And then you have the mixed bag ethnicities that appear to have some high-carbers and some ill-suited.

What we can be sure of at this point is that we should be eating 'Paleo' in the sense that the foods should be natural and have mother nature as their parent (not some chemist). Beyond that, I think the abstract you've linked provides evidence to this statement above all else: dogma is garbage. Find what works for you within the spectrum of natural foods.

Don said...

Strontium Pup,

Since varying the diet protein and carbohydrate content had no effect, and the diets had similar results, it remains possible that the results came from what the diets had in common, i.e. a ~30% fat content.


I had Bond's first book, but didn't know he was still active on the web. Thanks.

randyfeingersh said...

Your flexibility to change is quite refreshing.

Anyway, here is a very significant paper that is little known from the Candian Medical Association Journal in 1935 by I.M.Rabinowitch that's probably the longest true low fat high carb diabetes study ever done:


I look forward if you care to comment.


randyfeingersh said...

Your flexibility to change is quite refreshing.

Anyway, here is a very significant paper that is little known from the Candian Medical Association Journal in 1935 by I.M.Rabinowitch that's probably the longest true low fat high carb diabetes study ever done:


I look forward if you care to comment.


Steampowered god said...

Hmmm one quarter cup of macadamia(highest in monounsaturated fat with all the nutrients of nuts) has about 200 calories from fat, that's 10% percent of daily calories. And addition of monounsaturated fats has proven to be beneficial.

At least those who consume 2000 calories, will have a tough time reducing fat below around 20% if they consume such a small portion of the highest concentrated source of monounsaturated fat, unless eating a specially constructed diet.

So fat is unlikely to go significantly below 30%, and could very well easily be around that for many people eating healthy diets.