Will the waistline police ever leave us alone? Last week, it was the World Health Organization's (search ) nutrition guidelines. This week it's "obesity causes cancer" and "fasting improves health."
Researchers from the American Cancer Society (search) alleged that overweight and obesity cause up to 14 percent of cancer deaths among men and up to 20 percent among women.
We're expected to swallow these results without scrutiny since the study was conducted by the ACS, published in the New England Journal of Medicine and involved 900,000 adults.
Instead, I'm choking on the absurdity.
First, the study data are utterly unreliable — garbage in, garbage out.
The ACS collected the data in 1982 by soliciting 70,000 volunteers to interview 2 million friends and family about their health and lifestyle characteristics. Data on deaths was collected until 1999.
None of the health and lifestyle data were verified for accuracy. The researchers don't really know what or how much the study subjects ate, smoked, drank or exercised, for example. Not even the study subjects height and weight was verified.
The 70,000 volunteers weren't trained data collection technicians. They were amateurs asking potentially embarrassing lifestyle questions of others who had no incentive to answer accurately — even if they could.
Does smoking half of a cigarette occasionally make you a smoker? Does a double martini count as one or two drinks? How much do you really weigh?
The data weren't designed to test whether bodyweight is associated with cancer risk. Key cancer risk data weren't collected or considered by the researchers.
For example, information on family history of cancer, an indicator of genetic susceptibility to cancer and a major cancer risk factor, was ignored.
It is beyond belief that conscientious researchers would attempt to establish cancer risk without such critical information.
Using the poor quality data, the researchers could do no better than to produce weak — that is, dubious — statistical associations between increased bodyweight and cancer incidence.
How dubious?
We accept, for example, that heavy smoking is associated with increased lung cancer risk because studies report about 2000 percent more lung cancer among heavy smokers than non-smokers. The statistical association is so strong that it overwhelms any data quality issues.
In the bodyweight-cancer study, though, the alleged increases in cancer risk are on the order of 9 percent for those who are moderately overweight.
Such weak statistical associations have become such a problem in modern public health studies that the National Cancer Institute once went to the trouble of issuing a special media release discounting alleged increases in risk on the order of 100 percent or lower because of data quality problems.
The ACS researchers also have no biological explanation for how bodyweight might influence cancer risk. They mentioned the vague possibility that extra bodyweight may increase levels of certain hormones perhaps involved in cancer development. But that's just an unsubstantiated guess without persuasive supporting data.
But who needs data when you can spoon-feed junk science to a gullible media?
As for the study proclaiming fasting is healthy, the good news is it doesn’t rely on statistical hocus-pocus. The bad news is it relies on another notorious junk science trick — laboratory animal research.
Researchers reported in the Proceedings of the National Academy of Sciences (April 28) that mice who were only allowed to eat every other day (intermittent fasting) achieved the same "health benefits" — including lower blood sugar and more stress tolerance — as mice whose diet was reduced by 40 percent.
The purpose of the study is to strengthen the theory that we’d all be healthier if we’d just eat less.
The origin of the theory is the longtime observation that laboratory mice on restricted diets tend to live longer than those allowed to eat as much as they want as often as they want.
But the results of mice experiments cannot be extrapolated directly to humans. Mice aren't little people.
Moreover, it will be practically impossible to ever prove fasting has any beneficial effect on human health. Large, tightly controlled clinical trials lasting lifetimes would be required. No one is even contemplating such extraordinary efforts.
The waistline police, instead, intend to carpet bomb us with junk science until we knuckle under to their theory and crusade that food is deadly.
They have a tough case to prove, though, with life expectancy — the best overall indicator of public health — ever increasing despite our supposedly bad eating habits. U.S. life expectancy, in fact, just hit an all-time high of 77.2 years.
Of course, who would even want to live that long if they were only allowed to eat every other day?
Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).
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