I’ve been reading the rather excellent [junk food science](http://junkfoodscience.blogspot.com/) blog recently, and I’ve found it really interesting. The author shares some of the big research into obesity and nutrition. What’s really interesting is that many of the guidelines we hear on a regular basis seem to have no scientific credibility. And I don’t mean things that sound outlandish, like diets composed entirely of cranberries and algae smoothies, but really straightforward, everyone-believes this stuff. Things like;
– being overweight causes heart disease.
– eating fruits and vegetables is good for you.
– reducing your fat intake is healthy.
What’s interesting is how little is shown to be true by actual respectable science. In [this article](http://junkfoodscience.blogspot.com/2007/10/junkfood-science-exclusive-big-one.html), the author considers the results of the Women’s Health Initiative (WHI) Dietary Modification Trial. This trial was a study of nearly 50,000 postmenopausal women; some ate a ‘healthy diet’ high in fruit, vegetables, fibre, and whole grains, and low in fat. The control group ate whatever they felt like. The women were on the study for eight years, and at the end they were tested for heart disease, weight, cancers, etc. Here’s what the study found;
> “a dietary intervention that reduced total fat intake and increased intakes of vegetables, fruits, and grains did not significantly reduce the risk of CHD, stroke, or CVD in postmenopausal women.”
> “We found no evidence that lower intake of total fat or specific major types of fat was associated with a decreased risk of breast cancer.”
Colon and rectal cancer:
> “a low-fat dietary pattern intervention did not reduce the risk of colorectal cancer in postmenopausal women during 8.1 years of follow-up.”
> The women following a “healthy” diet for eight years didn’t end up thinner. They lost a bit at the beginning, but had regained it back years before the end of the trial, despite continued restrained eating and eating fewer calories (361 kcal/day less than they had been at the start of the study). During the last years of the trial and at the end, the researchers found an insignificant difference in weight changes between the intervention and control group of a mere 0.7 kg. They concluded:
>> “A low-fat eating pattern does not result in weight gain in postmenopausal women.”
Which is pretty amazing. Women on eight years of a recommended healthy diet were just as likely to get heart disease, clogged arteries, strokes, or three kinds of cancer, and were no thinner than the women who ate whatever they fancied.
A similar [study of male veterans](http://junkfoodscience.blogspot.com/2009/06/paradoxes-compel-us-to-think.html) found similar things. They followed about 1,000 men who were healthy in 1987, and followed up in 2004. By then, 208 had died. The overweight men in the study had a 34% better survivability than normal [BMI](http://en.wikipedia.org/wiki/Body_mass_index), whereas obese men had a 44% better chance of being alive.
That’s a fairly hefty foundation stone in a lot of the advice we see on how to live healthily. That being overweight leads to all manner of diseases and problems is heard so often that it’s incredible that it isn’t really backed up by the literature. And if that isn’t credible, then all the smaller studies and claims, about foods being either Good or Bad (chocolate, red wine, antioxidants, dihydrogen monoxide, polyungiptomobes) are probably equally suspect.
It’s got me intrigued. Over the next little while, I’m going to try to find the real papers, the real studies, that have managed to show what really does, and does not, have a benefit.
So my first aim will be to find out what effect cardiovascular fitness has on heart disease. Does getting fit help you avoid heart disease?