message on the "Stanford Swim Diet" aka "Zone Diet" aka "40/30/30
I think that this issue is of importance to everyone, in view of
the self-serving efforts of a few entrepreneurs to undo the
progress which has been made in helping people to understand the
health benefits associated with low fat diets.
I will excerpt Mr. Genreau's points and respond to each, in turn.
would be willing to refute the case presented for it below,
using logic and layman's terms.<<
I will try to do this.
Coleman (a sports nutritionist and exercise physiologist)
recommends 60% carbo - 25% fat - 15% protein for athletes (1).
And Nancy Clark, MS, RD, also recommends that 25% of an athletes
caloric intake come from fat (2). The percentage of fat
recommended in the Sears diet is only 5% higher. The big
difference is in the amount of protein.<<
Those were the personal recommendations of popular dieticians,
writing for the "masses" of recreational athletes. Other authors
have, based on considerable research data (not "theory") proposed
that the optimum carbohydrate for serious athletes in training
should be 70% or more (Devlin,J. Consensus statement on foods,
nutrition, and sports performance. J Sports Sci 9(suppl):iii,
1991). There is a difference between a practical goal for the
average person and the optimum goal for a motivated person.
least) 12 US patents. Is president of Surfectant Technologies,
Marblehead, MA. Has developed drug delivery systems for cancer
treatment, and done research on the role of fats in
atherosclerosis. He is author of the book "The Zone", which
presents his ideas about dietary endicrinology for athletes.
Sears himself and almost all the experts cited in these articles
are calling for such research.<<
Sears is an entrepreneur, who sells his book (currently 4th on
the NY Times best seller list), his own brand of 40/30/30 "energy
bars," and other things. A Medline search going back 15 years
revealed only a single paper relating to nutrition and physiology
(a letter to the editor of an obscure New England DENTAL journal
Sears B: Build a diet for life with fat. J Mass Dent Soc 1993,
42:204-5) and a few papers from 10-25 years ago dealing mainly
with methods for studying cell membranes. I could find no
publications dealing with "the role of fats in atherosclerosis,"
eicosanoids in athletic performance, or any other relevant areas.
lack of peer reviewed literature to support them. After all,
such literature can only be generated after the idea has been
considered important enough to be studied carefully and
funding/time have been provided to conduct some studies. If
peer reviewed literature is one's criteria for acceptance, then
wait for it.<<
It is not just that there is a total lack of data, it is that
Sears' "new theories" run contrary to mountains of consistent,
published data from virtually innumerable investigators. As
discussed below, the "new theories" are not just tenuous, they
are also fanciful, illogical, and internally inconsistent. Yet a
great many people are literally changing their lives (and, I
would say, putting their health in danger) on account of these
"new theories." I personally view this as being imprudent.
The following message was provided last week in the newsgroup
rec.sport.triathlon, by Andrew Coggan, PhD, an exercise
physiologist who has published extensively in this area:
"...For example, I know an Olympic medalist swimmer who used to
be a member of the Stanford swim team, which is often held up as
empirical proof that the balanced diet approach results in
improved athletic performance. He reports that they were free to
eat whatever they wanted, with only a mild suggestion from the
coaching staff that they give the balanced diet approach a
try...hardly a controlled experiment, to say the least. Likewise,
Mark Allen and Mike Pigg were clearly successful long before the
balanced diet approach came to the fore, so it seems likely that
their success both before and since is more related to other
factors (e.g., natural talent, hard work) than to these
relatively new theories..."
>>Sear's dietary ideas consider the hormonal impact of the food
idea that an athlete's primary energy source is glycogen (in
muscles), which is a stored form of glucose, and carbohydrates
supply glucose. According to Sears, the following chain of
events occurs when you eat too much carbohydrates:
glucose from the ***stream, storing it away
minutes or so after a high carbohydrate meal, causing them to
burn fat efficiently
to protein in our diets. The effects of glucagon are largely
opposite of insulin, encouraging the body to burn stored fat and
causing the body to maintain steady *** sugar levels within a
narrow range by releasing glycogen from the liver. <<
Basically, carbos are bad because they make us secrete more
insulin and less glucagon, and this makes us fat.
There is a beautiful saying in my field (cancer research): MANY A
BEAUTIFUL THEORY HAS BEEN RUINED BY AN UGLY FACT.
Consider the following facts:
THEORY 1. Does a high carb diet result in greater insulin
FACT 1. People with diabetes cannot make enough insulin to
satisfy even baseline needs. Their *** sugars are, therefore,
very high to begin with. If they were to be placed on a very
high carbohydrate, low fat, low protein diet, their insulin
requirements and *** sugar levels should go way up, according
to Sears, and they should be in big trouble.
Guess what: In a large study, a total of 652 diabetic patients
was placed on an 80/10/10 diet with moderate exercise, and their
responses were analyzed after three weeks. RESULTS--Fasting
glucose level was dramatically REDUCED, and 71% of 197 subjects
taking ****** sugar lowering agents and 39% of 212 taking
insulin were able to discontinue their medication. In other
words, they used LESS insulin and not more, as predicted by Sears
theory number 1. Of the 243 not taking medication, 76% REDUCED
their fasting glucose levels to normal levels, meaning that their
limited amount of insulin wasn't enough on a "balanced" diet, but
it was more than adequate on a high carb/low fat diet. ***
pressure was significantly reduced, and of the 319 initially
taking antihypertension ***, 34% had their medication
discontinued. Serum total and low-density lipoprotein cholesterol
were reduced by 22% and triglycerides by 33%. The subjects also
lost an average of 11 pounds in just three weeks (J
Cardiopulmonary Rehabilb 12:194-201, 1992).
So much for a high carb diet sending your insulin production into
overdrive and changing carbos into unsightly body fat.
THEORY NUMBER 2: Glucagon is good/insulin is bad, and we need
lots of protein to help us make glucagon.
FACT NUMBER 2: The effect of protein intake on glucagon and
insulin is quite complicated. Proteins are broken down to amino
acids, which are then absorbed. Amino acids provoke secretion of
BOTH insulin and glucagon. The effect of the insulin is to lower
*** sugar. This is what provokes the release of the glucagon
(which then raises *** sugar back to normal). Pancreozymin is
secreted by the stomach in response to a protein meal. This
hormone also stimulates glucagon release, to protect the body
from the glucose lowering effect resulting when amino acid
absorption stimulates insulin release. If protein is taken along
with carbohydrate (which prevents the fall in *** sugar), then
glucagon is not secreted. Thus, glucagon secretion is a
ying-yang, yo-yo mechanism to correct for what would be a metabolic
imbalance (hypoglycemia) from a high protein meal. Not all that
dissimilar from rebound hypoglycemia resulting from ingesting a
large bolus of simple sugars (not recommended), which provokes
release of too much insulin, low *** sugar, and a rise in
glucagon levels to correct the imbalance.
THEORY NUMBER 3: It is good that glucagon causes the body to
maintain steady *** sugar levels within a narrow range by
releasing glycogen from the liver.
FACT NUMBER 3: The main reason the glucagon is secreted is to
correct low *** sugar. "Steady" *** sugars are maintained
perfectly well on high carbo/low fat/low protein diets without
depleting one's glycogen stores (critically needed for serious
athletic training) to correct low *** sugar.
THEORY NUMBER 4: Carbos make you gain weight; fat helps you lose
FACT NUMBER 4: In a study of more than 200 subjects correlating
body fat, fat intake and carbo intake, as body fat increased,
percent of calorie intake derived from fat increased (p ...
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