Monday, May 28, 2007

How Skeptics do Diets

Okay okay, Ive been hard on the Biblotarians for how they do diets and their fitness advice.

Are skeptics any better? The current issue of SKEPTIC magazine has an article on diet and another on a supplement. How do they stack up to my amateur fitness-buff standards?

First is a short piece from The SkepDoc, Harriet Hall, M.D., "Dont Let Them Hoodia-Wink You"
Its short, sweet, and to the point. After writing a brief intro to the history of Hoodia and what people in the U.S. think it can do (suppress hunger, if you believe the diet pill commercials), Dr. Hall asks the question all skeptics are thinking: "What is the evidence?"

The answer: "At this point its strictly anecdotal." And what is the line that recites in my head every time I hear an anecdote used as 'proof'? A million anecdotes arent worth one, randomized, double-blind, controlled experiment.

Dr. Hall then points out what the experiments have shown:

"Products that have been tested have contained between 0.1 and 0.01% of the active ingredient claimed. One testing company estimates that half of the Hoodia products they test contain no Hoodia at all."
Well that wouldnt be so bad if the efficacious dose of P57 (the 'active' ingredient in Hoodia) was really small... but there have been no double-blind studies... soooo... Yeah, dont waste your $$$.

The next article is "The Gospel of Food: The Myth of the Doctrine of Naught", by Barry Glassner.
Now I will state up front that this article is about eating for general health. I dont just eat for general health, and I wouldnt recommend his conclusions for anyone hoping to run a marathon or get ripped. Hes writing for a majority of people wondering "What the hell am I supposed to eat???"

Glassner hits at the root of the problem of dietary guidelines and the research theyre founded upon, and believe it or not, its Hoodias problem! No double-blind studies!
"You cant give one person a T-bone and another tofu and have them believe they are eating the same thing. The closest that nutrition researchers come to randomized trials are experiments in which they assign people to eat particular foods rather than give them free choice."
There are more problems with this. Most studies on diet and disease are retrospective studies. Jimmy ate red meat every day, and he had a heart attack. Johnny never ate red meat, and hes fine. Okay, thats a correlation, but is that a causation? Nope.

Glassner, to my delight, also highlights more problems with 'diet' that I will preach over and over and over to anyone asking me what I eat, thinking that they can eat the same thing and have my physique:
"... He (Ronald Krauss) and other researchers have documented that individuals react very differently to low-fat or reduced-salt diets, for example, depending upon their genetic predispositions. One persons LDL or plood pressure plunges, while someone elses remains neraly unchanged."
Odds are, you cant eat what I eat to look like I look. If I ate what 'diet and fitness' magazines said I 'should' eat, I would die of starvation within a month (I eat a LOT). You have to experiment with your diet to see how you respond! It sucks! It took me years of keeping nutrition journals to figure out what I should eat, and what I need to keep in moderation (or stay the hell away from).

But remember, I have very specific fitness goals. Whats an Average Joe who just wants to avoid heart problems and cancer supposed to eat? This is the best advice ever from Marcia Angell (former editor of New England Journal of Medicine):
"Within limits they should eat the way they want to eat. What are the limits? I think they should eat in moderation, and I think they should eat as varied a diet as possible because thats good insurance. You dont put all of your eggs in one basket, or in this case, your health in one egg. You try to cover the waterfront because youre operating from a position of extraordinary ignorance, so your best bet is to eat a varied diet."
Eat a steak, if you want it! I dont want it, I think theyre gross, but eat a damn steak! But dont just eat steak! Eat a damn apple every once in a while! Maybe some eggs! How about a glass of milk? Gaining weight? Dont eat so much steak, but you can still eat the steak! YAAAAY!

You could make a whole new sub-magazine: SKEPTIC Diet, Fitness, and Supplement

But these articles are a good start-- give them a read!


Vacuous Implication said...

I think the most telling thing from the Hoodia-winked article was that Pfizer released its Hoodia research and the rights into the public domain. That screams, "Worthless!"

Actually, with the possibility that it's a liver wrecker, I can't see how it's still on the market.

ERV said...

Stupid Pfizer! Having to answer to the FDA! BAH! Money grubbing bastards.

Not like those nice supplement companies that Just Want to Help People(TM)


Oh I bet all that 'Hoodia' you can buy is still on the market for the same reason homeopathic arsenic is-- their aint nothin in it but water/inert ingredients ;)