2014 Rebuttal to U.S. News and World Reports Diet Ratings

U.S. News and World Reports | The Paleo Diet
As many of you are now aware, U.S. News and World Reports (USNWR) has just issued their annual ratings of Best Diets for 2014. As per their 2011, 2012 and 2013 evaluations, the DASH diet was rated number one by a panel of nutritional and health “experts,” and The Paleo Diet again emerged last out of 32 diets which were considered. We have previously addressed the USNWR report as it relates to the Paleo Diet in extensive detail in the Original Rebuttal to the USNWR. I have a few additional important points which follow:

I would like to point out a number of crucial flaws in logic along with a total breakdown of the scientific method in these types of artificial, media-generated reports that invalidate any wide sweeping conclusions about diet reached by the popular press, by individual member of the USNWR panel or by USNWR itself.

The 2014 USNWR diet ratings represent nothing more than the subjective rankings of 32 popular diets by a group of professionals, ultimately hand-picked by the editorial infrastructure at USNWR. Notably lacking in the makeup of this panel are academic and medical professionals with a background and publication record in human evolution, ancestral human diets and the application of this diet within a clinical setting.

The USNWR ratings represent a purely subjective appraisal of 32 popular diets and accordingly has little or no objective value from a scientific perspective because of numerous and glaring flaws in the research design of this report. Let me give you an example.

Say you would like to experimentally test three different diets (Diet A, Diet B and Diet C) on a single outcome variable (perhaps, blood pressure) to determine which diet was most effective in lowering blood pressure. Such an experiment would require that you test Diet A to Diet B, Diet A to Diet C and Diet B to Diet C. Scientists then run statistical tests on these three trials (A to B, A to C and B to C) to determine the effectiveness (or lack thereof) of all three diets and all three possible comparisons.

If we would like to test four different diets (Diets A, B, C and D) against one another for their specific effectiveness on blood pressure, it would require 6 individual experiments (A to B; A to C; A to D; B to C; B to D and C to D). As more and more diets are tested against one another, the number of experiments required to evaluate one diet against the next rises exponentially (actually factorially).

To test 32 diets against one another, would require 538 individual experiments and at least 538 statistical comparisons!

These 538 experiments have never been conducted. In fact, very few of the 32 popular diets evaluated by the USNWR panel have ever been examined in the scientific literature or tested against one another statistically. Without objective data, ratings of popular diets by this or any panel of “experts” represent nothing more than pure subjective speculation by the members of the panel. Clearly another “expert” panel with an entirely different makeup could be convened whose dietary ratings may vary entirely from the USNWR panel.

Like it or not this is how science works. Hypotheses must be formulated and statistically tested. If the USNWR panel believes the DASH diet is superior to The Paleo Diet, it must be experimentally tested. You cannot say that one diet is more effective than another diet without testing it statistically with either experimental or epidemiological (population) studies. So, to say that the DASH rates number #1 among all 32 diets for either a single outcome variable (say blood pressure) or multiple outcome variables (weight loss, blood pressure, blood cholesterol levels, ease to follow, satiety, etc. ) is absolute nonsense from a scientific perspective.

I recognize a number of well-known and well published scientists on the USNWR panel. These scientists would be the first to tell you that the USNWR ratings are subjective in nature and not based upon factual comparisons found in the scientific literature testing each of the 32 diets against one another.

In contrast, The Paleo Diet has been frequently examined in the scientific literature and shown to be effective in facilitating weight loss, improving cardiovascular risk factors and satiety while being more nutrient dense for the 13 vitamins and minerals most lacking in the US diet when compared to the USDA Food Plate (formerly the Food Pyramid).


Loren Cordain, Ph.D., Professor Emeritus

Related Rebuttals

Robb Wolf’s US News Ranks The Paleo Diet: 2014. Deja Vu All Over Again!

Nell Stephenson’s The Paleo Diet on the ‘Worst Of’ List…

Mark Sisson’s Why Does the Paleo Diet Continue to Receive Low Points from “Established Authorities”?

Ben Balzer’s Paleo Diet Fights Back

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32 Comments on "2014 Rebuttal to U.S. News and World Reports Diet Ratings"

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  1. Curt says:

    I do believe it is marketing propaganda put out by someone with an agenda. How many people do you think saw that headline and now believe a paleo diet is bad? You know the old saying, “If you repeat a lie often enough, it becomes the truth”.

    Why would, “well-known and well published scientists” allow their names to be associated with such useless garbage?

    Here’s what the winner (DASH Diet) recommends for breakfast…

    ¾ cup bran flakes cereal (¾ cup shredded wheat cereal) with 1 medium banana and 1 cup low-fat milk
    1 slice whole-wheat bread with 1 tsp. (unsalted) margarine
    1 cup orange juice

    I feel like I need an insulin injection just from reading that. As a diabetic who doesn’t use insulin anymore because of a low-carb/paleo diet, I wouldn’t touch the DASH diet.

    Why would anyone recommend a diet that promotes diabetes and why would any doctor recommend MARGARINE? Oh, that’s right…it falls within our government’s dietary guidelines so it must be good for you :)

  2. Scott Uk says:

    I love your work, but you’re mistaken when you say: “To test 32 diets against one another, would require 538 individual experiments and at least 538 statistical comparisons.”

    To test X different diets against each other would require ONE experiment with X different conditions, and ((X*X)-X)/2 statistical comparisons (controlling for multiple comparisons).

    So, to test 32 different diets against each other would require one experiment with 32 different conditions, and 496 statistical comparisons.

    That’s what ANOVA is for (and MANOVA if you have multiple outcome variables).

  3. I congratulate, a magnificent idea orthomol Vitamin d food sources

  4. Charles Grashow says:
    Loren Cordain, PhD

    “The macronutrient content of the experimental diet (38 % protein, 39 % fat, 23 % carbohydrate by energy) varied considerably from current western values.”

    Look at Table 3

    Macronutrient and other dietary characteristics in a contemporary diet based on Paleolithic food groups for females (25 yrs, 2200 kcal daily energy intake)

    Fat (g) 100.3
    Fat (% Total Energy) 39.0

    Saturated Fat (g) 18
    Saturated Fat (% Total Energy) 7.0

  5. Charles Grashow says:

    According to you the Paleo diet is LOW in saturated fat – isn’t it?
    Loren Cordain, PhD

    “The macronutrient content of the experimental diet (38 % protein, 39 % fat, 23 % carbohydrate by energy) varied considerably from current western values.”

    Look at Table 3

    Macronutrient and other dietary characteristics in a contemporary diet based on Paleolithic food groups for females (25 yrs, 2200 kcal daily energy intake)

    Fat (g) 100.3
    Fat (% Total Energy) 39.0

    Saturated Fat (g) 18
    Saturated Fat (% Total Energy) 7.0

  6. Charles Grashow says:

    Prof Cordain

    Have you changed your mind since you co-authored this paper?
    Optimal low-density lipoprotein is 50 to 70 mg/dl: lower is better and physiologically normal.

  7. Steve Dombek says:

    Their website claims 20 million visitors per month. Unfortunately with numbers like that it’s hard to say the ranking doesn’t matter. Lots of people are going to see it and be misinformed, and reach for a Slim-Fast (ranked #13!!) instead of giving Paleo a shot. That’s a shame, but in the long run the results will speak for themselves.

  8. Without science behind it, I don’t believe the USNWR article for one second. I enjoy living like a cavewoman and haven’t felt this rejuvenated in a long time. I’m sharing my paleo journey through Check out, follow, share YOUR story.

  9. Jason says:

    I have a question on the last sentence of Dr Cordain’s original article.

    “Actually, the most recent comprehensive meta analyses do not show fresh meat consumption whether fat or lean to be a significant risk factor for cardiovascular disease (20-25), only processed meats such as salami, bologna, bacon and sausages (20).”

    Does this only apply to cured meats. For example you can get uncured bacon and sausage?

    Thank you

    • Mark. says:

      Most processed meats labeled as uncured are actually cured, just with nitrates from celery and nitrites from sea salt. I suppose that one could flavor ground meat and cook it for something resembling sausage and eat fresh pork belly instead of bacon. I just reduce my intake a bit and don’t fret about it. I’m not convinced that there aren’t confounding factors that make cured meats seem more dangerous than they really are.

  10. Christopher Jensen says:

    The raters do not want to give paleo a fair shake because it could destabilise nutrition and the economy for those who push the nasty foods. I have been living the paleo lifestyle for little over two months and have lost over 25 pounds. The proof is in the pudding. Besides the dash diet only helps with blood pressure, nothing more. Being paleo or primal helps all around health and wellness and prevents a ton of man made diseases.

  11. Virginia says:

    I personally could care less about the rating of the paleo diet. It’s subjective and not scientifically based. What’s to knock about a whole foods diet that eliminates processed junk and GMO foods as much as possible and Promotes organic foods without pesticides? The proof is in the results of improved health, and reversal of chronic symptoms such as pain, migraines, swelling and inflammation, and slowing and improvement of auto immune diseases such as MS, RA, psoriatic arthritis, atopic dermatitis, crohns and celiac disease, as well as other inflammatory conditions. Furthermore, big food corps slam paleo due to the fear of loss of revenue. If everyone just switched to eating REAL foods, And stopped eating processed foods out of a box, or freezer, artificially manufactured Food STUFF, fast food (fake burger anyone), frankenwheat, and the big GMO crops of soy, and corn, big food corps and Monsanto that influence the FDA lose money. I’m not a fad diet person. This is a lifestyle. makeover change and I haven’t felt this good in years. And I’m not “foraging” in the woods hunting and gathering or making my own fire like a cave girl contrary to popular digs. Arguments who suggest such a thing for premise of this my being nutritionally sound way of eating have not done their research. No one died from eliminating bread, wheat and grains from their diet. Nor is it nutritionally necessary.

  12. I have been following a paleo, gluten free eating strategy for the past 2 years and have never felt this good in my entire life. For me your rebuttal is great and thanks for providing it.

  13. David Birney says:

    I could care less how they rate the diet. I myself have lost 105 lbs in 6 months doing IF and Paleo, and more importantly I have gotten off all my medication except for my Blood Pressure pills. My BP is actually under 120/80 for the first time in years, so I’m hopeful I will get to go off them in a few months too.

  14. Trevor Smith says:

    I was so frustrated when I saw all the articles about this report — Made me feel much better to read your rebuttal. Thanks for the great work Loren.

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