Tuesday, October 19, 2021

What Is The Most Fattening Food?

I came across this paper recently:

"Changes in Diet and Lifestyle and Long Term Weight Gain in Women and Men” (Mozaffarian et al., 2011)

From the illustrious New England Journal of Medicine.

The most notable authors (apologies to the rest!) are F. B. Hu—Frank Hu, the current Frederick J. Stare Professor of Nutrition and Epidemiology at the Harvard T. H. Chan School of Public Health (Harvard University, 2021a); D. Mozaffarian—Dariush Mozaffarian, Dean of Tufts Friedman School of Nutrition Science and Policy (Tufts University, 2021); and W. C. Willett—Walter Willett, the previous Frederick J. Stare Professor of Nutrition and Epidemiology at the aforementioned Harvard School  (Harvard University, 2021b), and until 2017 the chair of the department of nutrition—per Wikipedia as of this writing.

The three are the Holy Trinity of the Nutrition Establishment of the United States, and, by extension, the world. Combined, the three have written countless papers, editorials, and opinion pieces on the subject of health and nutrition.

This paper was a huge effort:

“We performed prospective investigations involving three separate cohorts that included 120,877 U.S. women and men who were free of chronic diseases and not obese at baseline, with follow-up periods from 1986 to 2006, 1991 to 2003, and 1986 to 2006.”

So this is a neat paper to find! What changes contribute most to weight gain, a topic of great concern to us all?

“On the basis of increased daily servings of individual dietary components, 4-year weight change was most strongly associated with the intake of potato chips (1.69 lb), potatoes (1.28 lb), sugar-sweetened beverages (1.00 lb)...”

So it’s potatoes! Potatoes are the most fattening food! Boy, that was easy.

But wait a minute, if one looks at their data for potatoes, one notices something very odd:


As you can see, they group ‘French fried’ potatoes together with ‘Boiled, baked, or mashed’ potatoes. But they group ‘Potato chips’ separately. And what’s most notable, is that there is a huge difference between ‘Boiled, baked, or mashed’ and the other two categories of potatoes, as far as weight gain goes. I decided to put a graph together:

As you can see, the worst individual item is French fried potatoes. Second is Potato chips, and the rest of the potatoes come in somewhere down the pack, between Sugar-sweetened beverages and Refined grains. Here’s another graph, where I drop the arbitrary (and misleading) Potatoes category, and the ‘Multivariable-Adjusted Change’ (which are likely bogus adjustments, as statistical adjustment is an art, not a science) to see what we really have here:

I dropped the Potatoes category because grouping ‘French fried’ together with ‘Boiled, baked, or mashed’ is very misleading, as it makes potatoes per se seem much worse than they are.

Now, ‘Boiled, baked, or mashed’ is another arbitrary sub-grouping of potatoes. A boiled potato is a very different thing from the other two categories, as it’s generally eaten on its own, without any added fat. Baked or mashed potatoes are generally served with some form of ‘Whole-fat dairy foods’—I checked a bunch of recipes and restaurant nutrition information on Google, and that seems to be a pretty fair statement. As you can see, ‘Whole-fat diary foods’, which includes butter, cheese, and whole-fat milk (see Table 2 above) is not particularly fattening on its own, as the authors note.

“Among Swedish women, higher intakes of whole milk and cheese were inversely associated with weight gain; as in our study, significant associations with weight gain were not seen for other dairy foods.” (Mozaffarian et al., 2011)

It’s unlikely that adding ‘Whole-fat dairy foods’ to a potato is going to make something that’s suddenly super-fattening, and that is not suggested by the data, but it might mean that a mashed potato with milk and butter (again, Google for recipes and nutrition info) is more fattening than a boiled potato, just due to the additive nature of the ingredients.

“A secondary analysis of potato subtypes showed that weight changes were positively associated with increases in the consumption of french fries (3.35 lb) and of boiled, baked, or mashed potatoes (0.57 lb) [numbers are multivariable-adjusted change].” (Mozaffarian et al.,2011)

So obviously the authors noticed this differential between the different varieties of potatoes as well, as they bothered to do a secondary analysis.

Considering the composition of a potato, which is mostly starch, one would expect it to have similar qualities to ‘Refined grains’, which are also mostly starch. And the ‘Boiled, baked, or mashed’ is indeed in the same neighborhood as ‘Refined grains’. I would expect that boiled potatoes alone should be right in the middle of refined grains, and the other two (baked and mashed) to be a bit higher, due to the added ‘Whole-fat dairy foods’, given the data presented.

But why are the other two categories of potatoes 6.5 and 3 times as fattening? What is the difference in ingredients between a boiled potato and a French fried potato?

The best-selling French fries, I’m assuming, are McDonald’s (McDonalds, Inc, 2021). The best-selling potato chips, according to Google again, are Lay’s (Frito-LayNorth America, Inc., 2021). So here is a comparison of potatoes: boiled (Condé Nast, 2018a), mashed (Condé Nast, 2018b), Lay’s, and McDonald’s:

And the ingredients? Well, the boiled potato is just a potato. The mashed potato includes butter, milk, and salt. The McDonald’s and Lay’s potatoes both list vegetable oils as the second ingredient.


Lays has a much simpler list of ingredients:

Now, the level of fatness doesn’t seem to correspond exactly to the fats, but all we have for the McDonald’s and Lay’s products is “Other fatty acids”; we don’t know exactly what they contained, and it likely varied over the course of this study. (Even the ingredients for Canadian McDonald’s fries differ from the American ingredients.)

The authors continue:

“Foods that contained higher amounts of refined carbohydrates — whether these were added (e.g., in sweets and desserts) or were not added (e.g., in refined grains) — were associated with weight gain in similar ways, and potato products (which are low in sugars and high in starches) showed the strongest associations with weight gain.” (Mozaffarian et al., 2011)

As the graph above shows, this is not correct. Potatoes become more fattening when the carbohydrate content is reduced, so long as it is replaced with vegetable oils. And it is a major effect, several times as fattening as potatoes containing either no added fats or non-fattening added dairy fats. And as we can see, this effect does not occur with higher levels of saturated fatty acids (SFA) as seen in the potato + ‘Whole-fat dairy foods’ combinations.

The summary graph (Figure 1) of the paper perpetuates this misrepresentation.

Note that the potato-weight gain connection exists across all three data sets they examined. If ‘Boiled, baked, or mashed’ were grouped separately from ‘fries’ or if ‘Fried potatoes’ were listed separately from other potatoes as I have done in the graphs above, it would be quite clear that there is something very different, and very obesogenic about fried potatoes, and given the simple list of ingredients in fried potato products, the problem must be the added vegetable oils.

So, according to these authors, the answer to my question, “What is the most fattening food?” is:

Vegetable oils. 

Since mass-produced potato products don’t use olive or other fruit oils, the answer is more specifically:

Seed oils.

P.S. Here's a graphic I produced later that makes it perfectly clear which categories of potatoes from the chart above are obesogenic:

Data from (Mozaffarian et al.; 2011)


It’s of course speculation as to why these investigators, who obviously noticed that fried potatoes were unusually fattening compared to non-fried potatoes, didn’t continue to drill down as I have done here.

But one clue to motivation is always the most obvious one: money.

The two most significant authors of this paper report having received fees from Unilever. Unilever, once the biggest producer of vegetable oils in the world, was in 2011 at the tail end of a years-long effort to divest itself of its vegetable oils businesses (Gelski, 2013). Unilever continues to be a major producer of foods that use vegetable oils as an ingredient.

Dr. Mozaffarian, especially, has produced multiple studies on vegetable oils, many of which have been funded by Unilever and Bunge, another major producer of vegetable oils (Otto et al., 2015). Drs Hu and Willett recently published jointly with several employees of Unilever, funded in part by Unilever (Zong et al., 2019), in which they reported:

“Total n-6 PUFAs were associated with a higher risk for type 2 diabetes in the age-adjusted model, but the associations were greatly attenuated after controlling for established type 2 diabetes risk factors, including BMI…” (Zong et al., 2019)

If, as appears to be the case in (Mozaffarian et al., 2011), “total n-6 PUFAs”, aka seed oils, are also causative in obesity, then adjusting for BMI would be invalid, as one cannot adjust by a factor that is involved in the causative pathway. To do so would have the effect of hiding the involvement of seed oils in both obesity and type 2 diabetes.

One can certainly imagine why a company that sells seed oils and products containing them might be interested making that relationship less than obvious.

Given this appearance of impropriety, it’s ironic that Dr. Willett had, and Dr. Hu has, the title ‘Frederick J. Stare Professor of Nutrition and Epidemiology’. Dr. Stare achieved a posthumous fame in (Kearns et al., 2016):

“Sugar Industry and Coronary Heart Disease Research: A Historical Analysis of Internal Industry Documents”

That was published in another prestigious medical journal, Journal of the American Medical Association: Internal Medicine. I’ll let this news article speak for the content of that paper:

“Sugar industry secretly paid for favorable Harvard research” (Bailey, 2016)

“Her paper recounts how two famous Harvard nutritionists, Dr. Fredrick Stare and Mark Hegsted, who are now deceased, worked closely with a trade group called the Sugar Research Foundation, which was trying to influence public understanding of sugar’s role in disease.”


Thanks to JR in the comments to this post, for reading the comments in the online version of this paper, and finding this:

All potatoes are not created equal

Drs. Mozaffarian et al have extended the important observation that the selective nutrient content of foods may be important determinants of weight gain. However, the authors missed an opportunity to critically examine the differences in the nutrient composition of french fries and chips compared to other potatoes. French fries had a 6-fold greater effect in weight gain and also differ from potatoes by having much greater omega-6 linoleic acid (7 gm/ 100 gm) vs. 0.03 gm/ 100 gm for baked potatoes (USDA Nutrient Database V 23). Potato chips have 13.4 gm of omega-6 linoleic acid /100 gm. Linoleic acid has been identified as a precursor for endogenous cannabinoids that are critical mediators of appetite and, in excess impair satiety and induce weight gain via mechanisms similar to pharmacological cannabinoids. In 1966 Dayton et al. reported linoleic acid induced weight gain in the LA Veterans study [(Dayton et al., 1966)]. Perhaps this difference in these biologically active fats distinguishes these potatoes and not the difference in total fat calories; the authors state that clear patterns were not seen in the relationship between weight gain and the energy density of the dietary components.

Joseph Hibbeln

Dr. Hibbeln is of course an investigator at the National Institutes of Health (NIH), who published the following year a study titled: 

"Dietary linoleic acid elevates endogenous 2-AG and anandamide and induces obesity" (Alvheim et al., 2012)


Alvheim, A. R., Malde, M. K., Osei‐Hyiaman, D., Hong, Y. H., Pawlosky, R. J., Madsen, L., Kristiansen, K., Frøyland, L., & Hibbeln, J. R. (2012). Dietary Linoleic Acid Elevates Endogenous 2-AG and Anandamide and Induces Obesity. Obesity, 20(10), 1984–1994. https://doi.org/10.1038/oby.2012.38

Bailey, M. (2016, September 12). Sugar industry secretly paid for favorable Harvard research [News]. STAT. https://www.statnews.com/2016/09/12/sugar-industry-harvard-research/

Condé Nast. (2018a). Potatoes, boiled, cooked in skin, flesh, without salt [Informational]. Nutrition Facts & Calories. https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2556/2

Condé Nast. (2018b). Potatoes, mashed, home-prepared, whole milk and butter added [Informational]. Nutrition Facts & Calories. https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/3004/2

Dayton, S., Hashimoto, S., Dixon, W., & Pearce, M. L. (1966). Composition of lipids in human serum and adipose tissue during prolonged feeding of a diet high in unsaturated fat. Journal of Lipid Research, 7(1), 103–111. https://www.jlr.org/article/S0022-2275(20)39591-2/pdf

Frito-Lay North America, Inc. (2021). LAY’S® Classic Potato Chips [Advertisement]. LAY’S®. http://www.lays.com/products/lays-classic-potato-chips

Gelski, J. (2013, July 26). AAK buys oils and fats supplier in Turkey from Unilever [News]. Food Business News. https://www.foodbusinessnews.net/articles/2547-aak-buys-oils-and-fats-supplier-in-turkey-from-unilever

Harvard University. (2021a). Frank Hu’s Faculty Website [Advertisement]. Harvard T.H. Chan School of Public Health. https://www.hsph.harvard.edu/frank-hu/

Harvard University. (2021b). Walter Willett’s Faculty Website [Advertisement]. Harvard T.H. Chan School of Public Health. https://www.hsph.harvard.edu/walter-willett/

Kearns, C. E., Schmidt, L. A., & Glantz, S. A. (2016). Sugar Industry and Coronary Heart Disease Research: A Historical Analysis of Internal Industry Documents. JAMA Internal Medicine, 176(11), 1680–1685. https://doi.org/10.1001/jamainternmed.2016.5394

McDonalds, Inc. (2021). Ingredients in the French Fries (Medium) Compostable Packaging [Advertisement]. McDonald’s. https://www.mcdonalds.com/us/en-us/product/french-fries-medium-compostable-packaging.html

Mozaffarian, D., Hao, T., Rimm, E. B., Willett, W. C., & Hu, F. B. (2011). Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men. New England Journal of Medicine, 364(25), 2392–2404. https://doi.org/10.1056/NEJMoa1014296

Otto, M. C. de O., Padhye, N. S., Bertoni, A. G., Jr, D. R. J., & Mozaffarian, D. (2015). Everything in Moderation—Dietary Diversity and Quality, Central Obesity and Risk of Diabetes. PLOS ONE, 10(10), e0141341. https://doi.org/10.1371/journal.pone.0141341

Tufts University. (2021). Dariush Mozaffarian [Advertisement]. Tufts Friedman School of Nutrition Science and Policy. https://nutrition.tufts.edu/profile/faculty/dariush-mozaffarian

Zong, G., Liu, G., Willett, W. C., Wanders, A. J., Alssema, M., Zock, P. L., Hu, F. B., & Sun, Q. (2019). Associations Between Linoleic Acid Intake and Incident Type 2 Diabetes Among U.S. Men and Women. Diabetes Care, 42(8), 1406–1413. https://doi.org/10.2337/dc19-0412




  1. What’s scary is not the unilever it’s that there are 9 (nine!) NIH grants. In other words, we paid for this crap.

  2. Who eats plain boiled potatoes? They are either adorned with (lots of) butter or gravy.

    Actually, find potatoes have a noticeable bitter taste, unless heavily salted and adorned with fat.

    1. Lots of people eat plain boiled potatoes. It's an ingredient in lots of dishes, like stew, or the dread New England Boiled Dinner I grew up eating.

      I guess it helps if part of your family is Irish. LOL

      But they are definitely improved with salt and butter!

    2. OK, my family wasn't Irish. Aside from stew, only things we boiled potatoes for were for making mashed potatoes or potato salad, both of which had dairy product, margarine, or mayonnaise, the latter two of which are of course full of PUFAs.

    3. Tucker, I loved our version of New England Boiled dinner, which we made with left over ham bone. My father and I would fight over the pork fat and of course, we still put lots of butter on our potatoes, along with the broth! (My red hair puts me in the Irish/Scottish ancestry column).

      Guess the difference is where I grew up (near Brad Marshall) lots of local dairies, hence LOTS of butter used on everything.

  3. So I don't feel so bad about my monthly surrender to potato chips, because I only eat the rare ones that are fried in avocado or olive oil. I preferred Boulder Mountain's coconut oil chips, but they were recently discontinued, and I haven't been able to find an alternative. (I tried making my own but it's just not the same.)

  4. There was a point in the 80s or 90s where CSPI pressured McDonald's and other fast-food restaurants into switching to vegetable oil from a saturated deep-fry fat for their french fries. Since this study started in the 80s, and french fries are one of the items studied, I'm just curious, is this switch reflected in any of the numbers? Not that I consider that kind of study very accurate or useful anyway...

    1. It was 1990, and it was McDonalds. Most of these studies started in 1986, so the early populations would have had less seed oils, correct.

      Most frying was done in some form of seed oils even then, as it had been pushed since 1961.

  5. Hi, nice work, data Vs. Conclusions.

    One of the original commenters from 2011 also noticed this potato dilemma.

    From discussions
    "No single metric appears to capture these complexities. Our findings highlight gaps in our (mechanistic) understanding...” my brackets and cherry picking.

    Missing: biochemistry. Sat fat bashing? Luckily only once thermodynamic laws. It is all Cico with behavioral!

    In Europe there are chips fried in olive oil. An oddity, maybe only in southern countries.

    French fries outside is rarity nowadays (oil). Home fries of sweet potato in coconut oil has replaced them. Briefly warmed up in owen grill to evaporate some moisture before frying once. No worries of soaked oil within potatoes, it is only ok!

    1. Nice find, JR! That's not just a commenter, that Joseph Hibbeln of the NIH, who published the following year a paper titled "Dietary linoleic acid elevates endogenous 2-AG and anandamide and induces obesity".

  6. Any thoughts on why nuts might be associated with negative weight change? Do they count peanuts as nuts? Nuts are generally high in LA. Could it be that the LA in nuts isn't well absorbed? Or is that only wealthy people consume nuts and they're not going to McDonalds?

    1. I'd suggest it's the latter, if you're eating nuts you're probably eating less junk food.

      It's a marker for a healthier diet.

  7. Not directly related to this specific post but somewhat related. Robb Wolf talks about working with Reno FD to try and improve health, through diet, and was hopeful to expand to other FD's.

    Well, think there is a new opportunity for FD's to listen to alternative diet information: https://roundingtheearth.substack.com/p/american-treatment-kit-movement-begins

    If there was an opportunity, think this may be it.

  8. If you wanted to gain weight (ie, muscle, you are a lifter who wants to bulk) BUT avoid PUFA, what would be your go-to food? Milk? Mashed potato? Rice?

    1. Or go for ground beef, dirt cheap, healthy and contains connective tissue for growing strong sinews. Kind regards, Gerlach.

    2. Yes, agreed. Ground beef is totally under-rated.

    3. Most of the fitness gurus say “gotta eat carbs to build muscle bro”… but yeah I like ground beef a lot.

    4. Muscles are built of meat, not carbohydrates. 😉

  9. I watched your interview on Dr berry YouTube I agree with you completely I looking forward to reading your work thank you I wish you had a YouTube I enjoyed listening thank you again

  10. Please talk about the behavioral aspects of eating too many PUFA's. Any articles you've found citing that it makes people anxious, aggressive (yelling stop) and generally, disagreeable? And.. Do you believe in keeping score of daily intake of Omega 6 /Omega 3 (Should our ratio be one to one?)

    1. That's a great idea, Patti. There are lots of really good papers in that direction, in fact.

  11. Dr DiPatrizio of UC Riverside gave a zoom lecture which I watched yesterday in real time through UC Irvine. Title "Pretty gutsy: endocannabinoids in peripheral tissues make you eat" I will contact him and see if it can be loaded on to youtube so everybody can access if they wish. Many mechanisms were worked out. However, punch line an antagonist of CB receptors with peripheral activity only will stop mice from getting fat without the pyschiatric side effects of rimonabant. Rimonabant is very powerful drug in humans on a "Western" diet...as powerful as knockout CBr's. Of course the "Western" diet used in mice model was corn oil gavage. Admitted when I questioned about the LA....he responded YES, his experiments show minimal carb effect but high response to LA (increased 2AG and AEA). Make mice fat and endlessly hungry but not for veggies. the mice went for 'Potato chips". Answer to all that....of course...a drug to antagonize perhipheral CBr's. It does work. I intend to ask him how he is funded. Other investigators wanted to know if it matters whether you smoke the THC or put it in the various stuff to eat. No intentions at all to curb the THC or the LA in the diet.

    1. Hap, can you get me in touch with him? I'd like to do an interview...

  12. I think I can contact him . I've asked for contact info from our Neurobiology department who sponsored the presentation. Is this for a podcast purpose? He might want to know more about it.

    somebody asked, although he never answered, if adding 18:3n-3 to the diet would be helpful...you know lets get on the Omega 3 bandwagon.

    Anyway, if you need my personal email once I have the information for you, I am happy to provide.

    1. Yes, it's for a podcast. I'm in the process of starting my own, and he'd be a great guest. His research figures heavily in my epic, in-progress obesity post.

      Just DM me on Twitter... Shouldn't post emails in public.

  13. you are right about that. but I thought you might not receive DM's.
    You might want to search for him on the internet and see publications.

    1. From you, I'll get them. ;) I tried to DM you in the past, and you didn't seem set to receive them.

      I've already got a database of DiPatrizio's papers.