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The Truth Behind The Atkins, Zone, and South Beach Diets
Traditional guidelines posted by the American Dietetic Association recommend that 45-65% of total calories be consumed in the form of carbohydrates, with guidelines for endurance athletes focusing on the latter end of these recommendations during training and competition.
By Kimberly Mueller, MS, RD
Posted Wednesday, 26 October, 2005
The carbohydrate intake of elite distance runners in the United States2,
Netherlands3, Australia4, and Southern
Africa5 have been measured at 49%, 50%, 52%, and 50% respectively.
Perhaps the most decorated distance runners in the world, however, are the Kalenjin
(Kenyan) runners who reportedly won a staggering 40% of all major international
middle- and long-distance competitions from 1987-1997.6
Interestingly, Kalenjin runners have a carbohydrate composition that tower over
their competition with measurements reporting 75+% or 10.4 grams carbohydrate
per kg of body mass, which may lead one to argue that running success and carbohydrate
intake are directly related.7
In fact, there is a plethora of sound research showing the profound performance
benefits associated with high carbohydrate intake, including optimal mental
functioning, muscle glycogen saturation, enhanced fat burning, protection against
protein/muscle breakdown, and improved immune function, just to name a few.8
Even so, such health authority as Dr. Atkins (Atkins Diet), Dr. Barry Sears
(Zone Diet), and Dr. Agatston (South Beach Diet) question the efficacy of high
carbohydrate diets for health and performance.
This has lead to an explosion of low carbohydrate products in the marketplace
and an adoption of new dietary habits by runners as means to shed body fat,
enhance performance, and optimize health. This article will give you the low
down on the effects of low carbohydrate dietary trends on running performance
and ultimately shed light on the top ten reasons why a dietary focus on healthy
carbohydrate sources (such as fruits, vegetables, legumes, and whole grains)
will always aid in health and running performance.
#10: Low carbohydrate diets leave you mentally drained
Finding your motivation levels at an all time low? If you are following a
low carbohydrate regimen, it is no wonder since the minimal amount of carbohydrate
grams suggested for optimal mental functioning is listed at 130 grams or just
over 500 calories. During the induction phase, Atkins followers are encouraged
to keep carbohydrate intake to no more than 20 grams per day; if you are running
enough, you can boost that up to 60-90 grams per day. You can see where this
may be a problem. Approximately 75-100 grams (300-400 calories) of carbohydrate
can be stored within the liver as glycogen. The energy stored within the liver
helps maintain blood sugars and also fuels both the brain and working muscles.
With blood sugars naturally rising and falling in 2-4 hour increments depending
on metabolic efficiency, liver glycogen stores constantly need to be replenished
with snacks consisting of some carbohydrate. When inadequate carbohydrates
are consumed, liver glycogen levels fall quicker, causing blood sugars to
drop; a lack of fuel being sent to the brain triggers dizziness, fatigue,
headaches, and an overall feeling of sluggishness known as “bonking.”
#9 Low carbohydrate diets trigger premature muscle fatigue during exercise
Do you find yourself flashing jealous looks at your competition as they blaze
by you at the end of that marathon while your muscles cramp and pace becomes
slower than a turtle? Just like a race car storing its fuel in a tank, the
human body stores carbohydrates as glycogen in the muscles and provides energy
for muscle contraction and relaxation during activity. When following the
high carbohydrate diet recommended by the American Dietetic Association, the
average human body will store just over 2 grams (8-10 calories) of glycogen
per pound of muscle tissue, with a potential for super-compensation with carbohydrate
loading protocols similar to that seen with the Kenyan elite runners.9
This amount of muscle glycogen will supply the energy needed to train for
~2-2.5 hours at a moderate-to-high intensity. Athletes following lower carbohydrate
regimens, however, have been shown to store approximately 45-75% less glycogen
as compared to their “carbo-loading” training buddies. Therefore, athletes
are more vulnerable to premature depletion of muscle glycogen, ultimately
compromising muscle function and leading to debilitating cramps, slowed pace,
reduced power output, and diminished endurance capacity, otherwise known as
“hitting the wall.”10-12 This is not surprising considering
Dr. Atkins suggests that athletes engaged in intense exercise for at least
45 minutes consume an increased, though still limited, amount of carbohydrates
in phase 2 of his program.
#8 Low carbohydrate diets compromise immune function
Ahhhh Chooo! Sound familiar? Prolonged intense exercise reportedly decreases
the plasma concentration of glutamine, an important fuel and precursor for
DNA and RNA synthesis in cells of the immune system, and may consequently
depress immune function making runners more vulnerable to infection in the
2 hours post workout.13 The immune suppression seen
in runners may also be attributed to elevated levels of the stress hormone
cortisol and a corresponding drop in lymphocyte production and T-cell activity
seen after completion of hard training. Interestingly, low carbohydrate diets,
specifically those yielding carbohydrate intakes less than 30 grams, seem
to exacerbate this effect.14 Dr. David C. Nieman, exercise
physiologist, has conducted much of the research looking at immune function
in runners and has discovered that carbohydrate supplementation both during
(~45 grams/hour) and immediately after (~45 grams) intense, prolonged exercise
helps reduce cortisol levels and maintain lymphocyte production, thereby helping
prevent infection.15
#7 Low carbohydrate diets affect mood
Yes, you may start to describe yourself as unpleasant to be around when following
a low carbohydrate diet! Many who are testing low-carbohydrate approaches
like Atkins and the South Beach Diet are reporting unusually elevated feelings
of anger, tension and depression, enough so that a new term ‘Atkins attitude,’
has been adopted to describe it. Judith Wurtman, director of the Women’s Health
Program at the Massachusetts Institute of Technology and the Adara Weight
Loss Center, has conducted studies on rats showing a connection between low
carbohydrate intake and low levels of serotonin – a neurotransmitter that
promotes feelings of happiness and satisfaction. In her research, rats placed
on a ketotic, or low-carbohydrate diet for three weeks were found to have
lower levels of serotonin in their brains. Wurtman believes that same effect
occurs in humans on low-carb diets, leading to pronounced feelings of depression
and sadness, even rage.16
#6 Low carbohydrate diets are often deficient in essential nutrients
With a lack of grains, fruits, and vegetables being consumed in low carbohydrate
diets, runners run the risk of developing dietary deficiencies of key nutrients
including dietary fiber, which can affect digestive health; vitamin C, which
can compromise immune function; folic acid, which may elevate risk for cardiovascular
disease; and magnesium, which may elevate risk for cramping and also compromise
bone health. A lack of fiber also increases your risk for cancers of the digestive
track (because transit time is lengthened) and cardiovascular disease (because
of fibers effect on fat and cholesterol). Low carbohydrate diets lack in the
phytonutrients / antioxidants found in fruits, vegetables, legumes, and whole
grains, all proven to aid in prevention of cancer and heart disease. 17,18
#5 Low carbohydrate diets slow muscle recovery
Having trouble walking down those stairs after last night’s killer track
workout? Consumption of carbohydrate-rich foods post-exercise will help enhance
recovery from workouts. Carbohydrate-rich foods cause a more rapid rise in
blood glucose, which in turn triggers the release of insulin or the “master
recovery hormone.” Insulin, the same hormone knocked by Dr. Atkins (Atkins
Diet), Dr. Barry Sears (Zone Diet), and Dr. Agatston (South Beach Diet), actually
facilitates the transport of carbohydrate, specifically glucose, from the
blood into the muscle cell where it can be metabolized to produce energy that
will prepare the muscle cell to do work again. Within 30-60 minutes post-exercise,
consumption of a carbohydrate-rich snack plus a small amount of protein (e.g.,
banana mixed in low-fat yogurt) has been shown to triple the rate of muscle
glycogen replenishment and muscle protein synthesis.19
Furthermore, as compared to a protein-only supplement taken post exercise,
a carbohydrate-protein solution has been shown to enhance rate of glycogen
storage by 5 times, thereby facilitating muscle recovery. 20
#4 Low carbohydrate diets increase risk for muscle injury during training
Do you find yourself constantly nursing little or big aches and pains? With
a low carbohydrate intake during endurance training, this is inevitable since
there is increased protein breakdown and consequent loss of lean body weight.
Furthermore, the biomechanics of your running stride may be negatively affected
due to cramping and muscle fatigue (also associated with depletion of muscle
glycogen stores), aka “the wall”, thereby causing a variety of new aches and
pains as well as muscle tightness. Finally, when insulin levels are chronically
low, as they often are with a very low carbohydrate intake, catabolism (breakdown)
of muscle protein increases, and protein synthesis is hindered.21
#3 Low carbohydrate diets increase risk for kidney stones
Ouch, it seems like something is stabbing me in the abdominal wall. I feel
nauseous. Yes, these are just some of the symptoms associated with passing
a stone. Sound like fun? When following a high protein, low carbohydrate meal
plan, both uric acid and calcium oxalate stones are more likely to form. In
fact, one study found that consumption of a low carbohydrate, high protein
diet for 6 weeks delivers a marked acid load to the kidney, increasing the
risk for stone formation.22 Combine this with dehydration during a race and
you are a prime candidate for being stabbed by a “stone” – I guarantee that
this won’t aid athletic performance. In 2003, former Ironman World Champion
and pro triathlete Tim DeBoom unknowingly passed a stone during the race,
which lead him to pass out and be whisked off to the medical tent… a medical
DNF.
#2 Low carbohydrate diets can diminish bone health
Find yourself constantly dealing with stress fractures? Individuals consuming
a higher ratio of protein to carbohydrates run the risk of developing brittle
bones or osteoporosis. When the body digests protein, the kidneys work overtime
to filter the toxic byproducts produced during the breakdown of protein. Once
filtered, protein is excreted in the urine; however, along with protein, there
is increased urinary loss of calcium, which can ultimately compromise your
bone health, thereby increasing your risk for bone fracture. In fact, consumption
of a low carbohydrate, high protein diet over 6 weeks has been shown to significantly
decrease estimated calcium balance and may increase the risk for bone loss
and stress fracture.22 Injury of the bone will definitely
inhibit maximum fitness performance.
#1 Low carbohydrate diets can trigger joint pain
Protein-rich sources such as meats, poultry, seafood, and eggs commonly consumed
as part of a high protein regimen contain high levels of purines, which raise
blood levels of a compound called uric acid. An excess of uric acid in the
body causes gout, which is a form of arthritis. Elevated levels of uric acid
in the blood may lead to needle-like uric acid crystals in joints, triggering
pain. A new study published in the New England Journal of Medicine has confirmed
the correlation between high protein intakes and gout. The researchers studied
47,150 men who had no history of gout at the beginning of the study. During
the 12 years of the study, they documented 730 confirmed cases of gout. The
relative risk of gout among men was highest among men with the highest intake
of meat and seafood. They concluded that higher levels of meat and seafood
consumption, like that seen in low carbohydrate meal plans, are associated
with an increased risk of gout.23
Low carbohydrate diets are not fun and certainly won’t help aid running performance.
Resist the urge of jumping on the latest “fad diet” bandwagon and continue your
high carbohydrate ways, implementing such nutrient-rich foods as fruits, vegetables,
whole grains, and legumes. Your muscles and body will thank you. There are countless
ways to incorporate tasty, disease-preventing, sports-enhancing carbohydrate-rich
foods into your diet without getting bored. Get a jumpstart on the day by trying
the following quick, healthy, tasty, and balanced carbohydrate-rich breakfast:
Blend ½ cup old fashioned oats, ¼ cup natural granola, 2 Tbsp slivered almonds,
¾ cup mixed berries, and 1 cup nonfat milk. Cook in microwave for 3-4 minutes.
Healthy carbohydrate trails.
Kimberly J. Mueller, MS, RD, is a Registered Sports Dietitian and competitive
endurance athlete who provides nutritional counseling and meal planning to athletes
worldwide. You can contact her at kim@kbnutrition.com . Information on her services
can be found at [LINK:http://www.kbnutrition.com]www.kbnutrition.com[/LINK] .
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Info on Diet Trends
Atkins
Zone
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