Man bites dog
Newspapers are always on the lookout for man-bites-dog kind of stories to sell papers. The more off beat the story, the more it flies in the face of what seems normal, the more newsworthy it is, at least in the eyes of the inky wretches who publish the dailies. It shows just how deeply ingrained in the minds of so many is the notion that dietary fat is bad for us when a series of studies showing that cutting fat from the diet doesn’t do squat makes the front page headline of the New York Times, the country’s most influential paper. And I don’t mean just the front page, but the actual top-of-the-page, main headline. The idea that fat might not be harmful is apparently a man-bites-dog story of the highest order.
Here’s the headline, right up top.
Low Fat Diet Does Not Cut Health Risks, Report Says
The first paragraph of the accompanying article sums it up pretty nicely:
The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.
USA Today weighed in with an article entitled
Cutting Fat Alone Isn’t Enough, Women Advised
The Knight-Ridder news service, the providers of copy to many local papers including ours headlined their article
Low-Fat Diet Fails to Cut Risk
The reports referenced in these articles were three studies appearing in this week’s The Journal of the American Medical Association detailing the results of a massive, government-funded ($415 million) study, The Woman’s Health Initiative, showing that postmenopausal women who followed a low-fat diet for 8 years suffered the same rates of heart disease, colon cancer and breast cancer as those who ate what they wanted.
Almost 50,000 overweight women aged 50 to 79 were divided into a study group (the low-fat group) and a control group. The study group was given intensive dietary counseling and much hand holding. Subjects in this group were instructed to reduce their fat intake to 20 percent of their total caloric consumption and to increase the amount of fruits and vegetables to at least five servings daily and grains to six servings daily. This group
received an intensive behavioral modification program that consisted of 18 group sessions in the first year and quarterly maintenance sessions thereafter. Each group had 8 to 15 women and was led by a specially trained and certified nutritionist. Each participant was given her own total fat gram goal based on her height. The intervention emphasized self-monitoring techniques and introduced other individually tailored and targeted strategies, such as motivational interviewing.
The members of the control group were given a copy of Nutrition and Your Health: Dietary Guidelines for Americans and sent on their way.
All the heavy duty counseling paid off in that the women in the study group did manage to reduce their fat intake from about 38 percent to 24 percent of calories by the end of the first year and to 29 percent by the end of the study. The women in the control group, who also started at 38 percent, reduced their fat intake to 35 percent by the end of the first year and had drifted back up to 37 percent.
When the study ended and the incidence of cardiovascular disease, breast cancer and colon cancer in the two groups was tallied, there was virtually no difference between the two groups.
I felt that the New York Times had the most even-handed coverage of these reports, although, as we will see, they didn’t do their homework very well. The paper quoted extensively from Dr. David A. Freedman, a statistician at the University of California, Berkeley, who isn’t connected with the study but has published extensively on the design and analysis of clinical trials. Dr. Freeman, who basically opined that the results should be taken seriously, opined:
The studies were well designed and the investigators tried to confirm popular hypotheses about the protective effect of diet against three major diseases in women.
But, the diet studied here turned out not to be protective after all.
We, in the scientific community, often give strong advice based on flimsy evidence. That’s why we have to do experiments.
Needless to say, these findings were a huge shocker to the reduce-your-fat-intake-and-you’ll-decrease-your-risk-for-everything crowd. And, as you might imagine, excuses were thick on the ground.
Dean Ornish, who is fast aboard the low-fat freight train hurtling pell-mell toward irrelevance and oblivion, complains that the women didn’t lower their fat intake enough, and that they didn’t eat enough fruits and vegetables, and that the study wasn’t long enough. If it had gone on for a few years more, says the author of a number of low-fat books, a difference between the two groups might have immerged.
Yeah, well, ‘might’ won’t feed the whippet.
I was struck by the realization of exactly how difficult it must be to reduce fat in the diet to the 20 percent range. These women who all had loads of hands-on counseling and care during the first year could reduce their fat intake to 24 percent and no lower.
After a careful review of these papers a couple of other things caught my attention.
The first thing was that although the women in the study group reduced their fat intake, not only were they not protected against disease, they didn’t really lose any weight to speak of. Most of the cut-your-fatters such as the above mentioned Ornish believe and propound that reducing fat will bring about weight loss. Ornish’s best-selling book Eat More, Weigh Less actually instructed readers not to worry about anything but cutting fat. As long as fat intake goes down, so will weight.
Sorry, Deano, but these studies prove you wrong even there. But, who knows, maybe if the studies had lasted a little longer, the weight loss would have become apparent.
The other thing I noticed was that not only did the women in the study group cut the fat, they cut the calories. At the start of the study the women were consuming 1790 kcal per day. After one year their intake was down to about 1500 kcal daily and continued to drift down a tiny bit more to 1431 kcal by the end of the study. So, these women consumed roughly 300 fewer kcal per day over the course of the study, which calculates out (300kcal/day times 365 days/year times 8 years) to a reduction of about 876,000 kcal in all. If we divide that 876,000 kcal reduction by 3500 (the number of kcal in a pound of fat), we find that these women should have each lost about 250 pounds, which would have been difficult since they started with an average weight of about 170 pounds. Well, not only did they not lose 250 pounds, they didn’t lose any weight at all. So what happened?
Obviously something is amiss.
In going through the paper on cardiovascular disease I came upon the following paragraph about how the caloric intake as well as the macronutrient intake was determined in the Methods section:
All participants completed an FFQ (food frequency questionnaire) designed specifically for the study at baseline and 1 year. Thereafter, one third of the participants completed the FFQ each year in a rotating sample: completion rates were 100% at baseline and 81% thereafter. Data on follow-op dietary intake were computed from FFQs administered from years 5 through 7 (designated as year 6 follow-up), thus including all the participants.
Here is an interesting note:
Four-day food records were provide by all women prior to randomization.
As we saw in a post not too long ago, FFQ are next to worthless. Four-day food diaries are much more accurate, but much more costly. The directors of these studies spent $415 million to do this part of it. I’m sure they spent a bunch getting and evaluating the baseline intake, which at about 1800kcal/day sounds right for 50-79 year old women. Then they went the cheap route to get the follow up data. The fact that according to their data these women were consuming roughly 17% fewer calories per day over the course of the study and not losing weight didn’t tip the researchers off that something was amiss.
Not only didn’t it tip them off, they thought it was a helluva study. Dr. Michael Thun, a director of research for the American Cancer Society, was quoted in the New York Times as describing these studies as being so large and so expensive that they were
the Rolls-Royce of studies.
Someone needs to tell Dr. Thun that it’s not the amount of money spent, but the quality of the data that makes a good study.
The only thing that keeps me from writing these studies off as a waste of time and money is the fact that the control group also consumed way, way fewer calories as determined by their FFQs and didn’t lose any weight over the 8 years. I guess we can make the assumption that the subjects in both groups fudged their FFQs proportionately and so at least the differences in macronutrient composition are relatively valid.
So with all due respect to Dr. Freedman, the statistician at the University of California, Berkeley, I don’t believe the studies were particularly well designed. I would feel a whole lot better about them if they had used a different methodology to obtain their dietary data.
It’s a real shame to spend $415 million of our dollars—yours and mine—and not get anything better than this.