An exercise in vitriol rather than sound journalism

Gary Taubes from the March 2003 issue

(Page 2 of 6)

Here's the specific context: Farquhar is quoted only in the last paragraph of my story. It follows directly from a discussion of my own difficulty in accepting the seemingly counter-intuitive possibility that fat might be beneficial to one's health and weight, and carbohydrates detrimental. The story then ends with the Farquhar paragraph:

This is the state of mind I imagine that mainstream nutritionists, researchers and physicians must inevitably take to the fat-versus-carbohydrate controversy. They may come around, but the evidence will have to be exceptionally compelling. Although this kind of conversion may be happening at the moment to John Farquhar, who is a professor of health research and policy at Stanford University and has worked in this field for more than 40 years. When I interviewed Farquhar in April, he explained why low-fat diets might lead to weight gain and low-carbohydrate diets might lead to weight loss, but he made me promise not to say he believed they did. He attributed the cause of the obesity epidemic to the ''force-feeding of a nation.'' Three weeks later, after reading an article on Endocrinology 101 by David Ludwig in the Journal of the American Medical Association, he sent me an e-mail message asking the not-entirely-rhetorical question, ''Can we get the low-fat proponents to apologize?"

I had interviewed Farquhar over the telephone on April 25, 2002. Two and half weeks later, we had the following aforementioned e-mail exchange: Farquhar initiates the exchange with his e-mail using the "apology" line.

From: Dr. John Farquhar
To: [e-mail]
Sent: Friday, May 10, 2002 7:55 PM
Subject: article on glycemic index
dear mr taubes
you may find a recent article in jama of interest in a search for blood sugar, a compensating increase in insulin, and an increase in
"hunger". the article in question is by ludwig--- jama 2002;287:2414-2423 you recall that i believed, in contrast to reaven perhaps, that the blood sugar swings could contribute to post-prandial hunger and,
thus, could be a factor that would contribute to obesity. (see page 2417 of ludwig's article). he adds some fancy biochemistry that you may find interesting. can we get the low-fat proponents to apologize? hope the article is coming along well. regards, jack farquhar

I then replied to Farquhar, asking him if he meant what he said, and whether he minded if I used the line in question.

Jack;

Thanks for the note. I'm featuring Ludwig prominently in the article. My idea is to portray the glycemic index and low carb diets docs as promoters of the alternative hypothesis to the low fat dogma. And, of course, one implication of the alternative hypothesis is that those low-fat proponents are at least part of the reason for the obesity epidemic. So were you just having fun with me when you wrote that maybe they should apologize, or do you, at least on occasions, wonder if it's true?

All the best,

Gary

Then Farquhar responded. Readers can judge for themselves whether Farquhar's take on the exchange and how I used it is justified:

From: Dr. John W. Farquhar

To: gary taubes

Sent: Sunday, May 12, 2002 8:17 PM

Subject: Re: article on glycemic index

dear gary--yes, i do think that they should apologize, but i don't expect it--so, that part is kidding. there is a long trail of nay-sayers in the CV medicine area. you might consider doing an article on sodium at some point.

i hope that i did make it clear that i believe the "low fat is good, therefore lower fat is better" crowd is dead wrong on many fronts--including that it is a good way to lose weight.

i know that low fat diets are really very bad for the overall type of lipid pattern that emerges. incidentally, ludwig didn't give that sufficient prominence. i believe that this more harmful lipid pattern accounts for the major disadvantage of low-fat diets (namely, that triglycerides rise, bringing HDL cholesterol down in the process and creating the "small dense" type of LDL that is more harmful than the larger varieties).

regarding the possibility that low fat diets contribute to the obesity epidemic--i am remaining a bit cagey on that point. i think that it might contribute, given the swings of glucose and insulin--and the possibility that an increase in hunger occurs on the tail end (when the insulin overcompensates and the blood sugar falls---or, at least, starts to fall and a compensating drive to snack keeps it from falling, assisted by a bit of catecholamine release). i thought that ludwig gave some support for that notion. in your interview with me i believe i emphasized that the portion size issue was staring us in the face and that the passive response of eating what is in front of us certainly gives the average person more calories than they would choose on their own. all the stuff about soft drink sizes going up, etc, etc.

of potential interest to you is that the famous dean ornish was recently not as dogmatic as i expected. i had to miss the session, held at stanford last saturday, because of my medical school class reunion. the session had reaven and ornish debating (as well as other speakers on other topics). i was told that ornish agreed that low fat diets make triglycerides rise, (a remarkable admission!!!)--he said his purpose of advocating such diets was to assist in weight loss (i need to confirm this point with jerry reaven), and to find an easy way to cut down on saturated fats. jerry and i would challenge the assertion that low fat diets work on weight loss better than any type of lowered calorie diets---this of course begs the question of whether these low fat diets are less successful than others.

regards, jack

Moving on, we get to Fumento's disagreement with my use of percentage of fat as a legitimate variable in the obesity epidemic. He says it's true that the percentage is decreasing, as I reported, but irrelevant: "The amount of fat consumed has been steadily climbing, as has consumption of all calories. Individual caloric consumption jumped from 3,300 calories per day in 1970-79 to 3,900 in 1997, an 18 percent increase. Per-person consumption of fat grams increased from 149 to 156, a 4.5 percent increase."

Fumento's source for these numbers, although he doesn't cite it, is the U.S. Department of Agriculture. The USDA has a variety of mechanisms for estimating macronutrient intake--i.e., protein, carbohydrates and fat--and has published a variety of reports on the subject. For instance, in April 1998, the USDA published an article entitled "Is Total Fat Consumption Really Decreasing?" This article reported that average total fat consumption for men aged 19 to 50, for instance, dropped from 113 grams per day in 1977-78 to 96 in 1989, the period that encompasses the beginning of the obesity epidemic. In 19- to 50-year-old women, the relevant numbers are 73 grams of fat per day in 1977-1978 and 62 grams in 1989.

Fumento prefers to use what are known as food availability data, as do I in most circumstances, although not this one. The USDA calculates how much food is provided by industry, and then adds imports, subtracts exports, and tries to adjust for waste--i.e., how much food is eventually thrown out. Fumento's data could have come from any number of these USDA reports but one that provides the same numbers is "Nutrient Content of the U.S. Food Supply, 1909-1997," by S. Gerrior and L. Bente of the Center for Nutrition Policy and Promotion (Home Economic Research Report No. 54). On page 26, Gerrior and Bente report that fat consumption from red meat, butter, lard and milk products all declined during the 1970s and 1980s. Thus the 7 gram per day, 63 calorie increase in total fat consumption noted by Fumento, was due to "the greatly expanded use of fried foods by the fast-food industry and in food service outlets as well as the increased use of salad oils on salads consumed both at home and away."

While the increase in fried foods might seem like a bad thing, the increase in oils on salad dressing would seem to be a good thing. The point, however, is that this particular data measures the availability of these fats in the food supply and, as Gerrior and Bente then emphasize, this particular category--cooking and salad oils--is almost impossible to estimate accurately:

While food supply estimates reflect trends in the availability of fats and oils for human food, they have never accurately measured the amount of food eaten because the portion of food wasted or discarded is difficult to determine. With the growth of the fast-food industry in the past three decades, it has become even more difficult to estimate the waste portion or discard of deep-frying fats. Since this discard is not available for human consumption, these estimates are limited as indicators of actual intake. A 1993 study estimated that about 50 percent or more of deep-frying fat used in food service operations is discarded after use and is not available for consumption. Reliable estimates of total fats and oils are difficult to determine partly because the actual amount of frying fat discarded by food service operations, particularly fast-food restaurants, varies with the type of the establishment.

As a result, the numbers Fumento uses to bolster this point are the least accurate available. It is the primary reason that I use percentage of fat calories, and may be why Willet does as well. It's safe to say that percentage of fat calories has been decreasing; it's a dubious proposition to make that claim about the total fat consumption.

More interesting, however, is what Fumento skates over in his quickie analysis: those extra 600 calories per day. Using the same report and this time taking Fumento's 1978 to 1997 as the period of interest, the American food supply, minus estimated wastage, offered up 448 more calories of carbohydrates, 48 more calories of protein and 63 more calories of fat. Fumento might want to blame the obesity epidemic on the extra 63 fat calories of fat or even the extra 48 protein calories, but he'll have to ignore the 448 calories from carbohydrates to do it. Under the circumstances, what I said in my article seems like a reasonable assessment: "If these trends are correct, then the obesity epidemic can certainly be explained by Americans' eating more calories than ever -- excess calories, after all, are what causes us to gain weight -- and, specifically, more carbohydrates. The question is why?"

Comments

|10.22.09 @ 3:56PM|#

Having read all three pieces in this debate, Fumento's critique of Taubes is so wholly inadequate I feel embarassed for him, and disappointed that Reason didn't vet Fumento seriously before publishing his original critique of Taubes. Taubes' position is increasingly permeating the research community and will likely be vindicated, leaving Fumento's piece as an embarassing example of Reason failing its mandate to provide critical analysis of contemporary debates. Reason's standards should be higher than merely being a forum for dissent -- you should have some standards for the dissent, and recognize dogmatic clinging to establishment thinking when you see it. The sooner the Lipid Hypothesis dies and refined carbs are recognized for their negative health effects the better the health of the world. We owe Taubes a serious debt of thanks for his integtrity and iconoclastic pursuit of reason. He shouldn't have had to offer this defense, likely only read by a fraction of those who read the original critique.