From: jmoulder@mis.mcw.edu
Newsgroups: rec.bicycles
Subject: Re: All that fat(long)
Date: 14 Aug 92 11:14:18 CDT
Organization: Medical College of Wisconsin

>>But what does this have to do with cycling?  Not much

A lot

The epidemiological, clinical and laboratory evidence linking dietary fat
intake and disease is quite clear, and so should be the message for bicyclists:

KEEP YOUR FAT INTAKE BELOW 30% OF CALORIES
  
Riding will probably improve your serum lipid profile and *may* decrease your
cardiovascular risk, but it wont lower your cancer risk.

There three somewhat separate issues entangled in this thread.  

*First, there are old studies from the insurance industry correlating body
weight and life expectancy.  These are the basis for the "optimal body weight"
tables that you find all over the place.   Those studies showed that people
with normal body weight and minimal variations in weight over time live the
longest.  More relevant to bicyclists:

Vlasov VV, Longitudinal study of health status of pilots: changes in body
weight. Kosmicheskaia Biologiia I Aviakosmicheskaia Meditsina: 25:55-57, 1991.
"On the basis of medical monitoring of the flying personnel, their body weight
variations as a function of age and disease were studied. . . It was
demonstrated that the airmen who remained healthy for a long period of time had
body weight values close to the group mean and age-related body weight gain
within normal limits. The subjects who fell ill when younger than 28 years had
a high body weight and those who fell ill at the age of 28-32 years had a low
body weight which increased drastically at the age of 30-35 years."

*Second, a wide variety of studies show an association between dietary fat
intake, serum lipid profiles, and the development of cardiovascular diseases.
Thus, many scientific societies (e.g., American Heart Association, NIH)
recommend a maximal intake of 30% of total energy by fats.  Serum lipid
profiles are influenced by heredity, diet and exercise.  It is clear that a low
activity life-style will compound the cardiovascular risk associated with a
high fat diet.  I cannot, however, find any studies that show that a
high-activity life-style will *counteract* the cardiovascular risk associated
with a high fat diet.  

*Third,  a high fat diet is associated with an increased risk of cancer, and
there is absolutely no reason to think that a high activity life-style with
counteract this risk.

You don't have take just my word for this.  See:

Doll R: The lessons of life: keynote address to the nutrition and cancer
conference. Cancer Research: 52(7 Suppl):2024s-2029s, 1992.
  "[There is] a consensus among epidemiologists that diet might be responsible
for 30-60% of cancers in the developed world. . . [It is] also broadly agreed
that the principal changes required . . . [are] a reduction in the consumption
of fat; an increase in the consumption of fruit, green and yellow vegetables,
dietary fiber. . . "

Weisburger JH.  Wynder EL: Dietary fat intake and cancer. Hematology - Oncology
Clinics of North America:5:7-23, 1991.
"International, multidisciplinary biomedical research in the field of nutrition
and cancer has led to the recognition that the traditional Western total fat
intake of about 40% calories constitutes a major risk factor for cancer of the
postmenopausal breast, distal colon, pancreas, ovary, endometrium, and probably
prostate. The underlying complex mechanisms have been sketched out, justifying
public health promotion activities involving reduction of fat intake to 20 to
25% of calories, facilitated by the deliberate marketing of low-fat products by
the food industries."

John Moulder (jmoulder@mis.mcw.edu)
Radiation Oncology
Medical College of Wisconsin