How
'net carbs' can hurt athletes
By
Ashley Kipp
from roadcycling.com
Over
the past several decades, American weight loss
trends have shifted from low-fat, low-calorie, to
the strict regimens of the “Grapefruit Diet” or
the “Cabbage Diet,” to the current miracles of
the “low-carb” diet. Recently, it seems like
everything revolves around controlling
carbohydrates, and athletes are getting caught up in
the frenzy. What athletes often fail to realize is
that low-carb diets were designed for significantly
overweight, sedentary people; they were not designed
to supply the nutrition active people need to
support exercise and training. While small ‘net
carb’ numbers are welcomed by low-carb fanatics,
athletes should regard these same numbers as energy
that’s been stolen from them.
Grocery
store aisles are lined with low-carb snack bars,
low-carb breads, and even low-carb catsup. Honestly,
if someone is eating enough catsup to be worried
about its overall contribution to their carbohydrate
intake, there are probably some other eating habits
that need to be addressed. Fast food chains have
also embraced the fixation with bashing
carbohydrates. Low-carb burgers without buns and
low-carb sausage, egg, and cheese breakfast bowls
fill television and billboard advertisements day
after day. For most people, in an examination of the
connection between extra body weight and frequent
consumption of fast food hamburgers, it’s not the
bun that’s the problem.
The
claims that backers of the low-carb diet trend are
taking are that sugar and refined carbohydrates
(like bread, pasta, rice, and cereal) increase the
body’s production of insulin and thus promote body
fat storage. Further statements argue that the
insulin “spike” caused by carbohydrates
eventually causes “insulin disorders” which
greatly increases the risk of obesity, coronary
heart disease, and diabetes. Low-carb diets are
based on the goal of eliminating the blood sugar
“spikes” that supposedly lead to and cause
insulin mediated storage of carbohydrates as body
fat.
What
Is a ‘Net Carb’ Anyway?
In
an effort to reduce the amount of carbs that are
reported on product package labels, manufacturers
have come up with the term: ‘Net Carbs.’ What
this refers to is the number of total carbohydrates
in a serving size of a product, minus the fiber
content of the food exceeding 5 grams per serving,
and also minus the sugar alcohols that are said to
have little or no effect on blood sugar. Because
fiber is generally indigestible and sugar alcohols
(hydrogenated chemicals designed to compensate for
the bulk missing from the lack of carbohydrates in
the product) are not absorbed very well,
manufacturers do not report these numbers as
“impact” or ‘net carbs.’ It would seem that
the solution to weight loss is easy… consume food
that is not digestible.
Where
Do the Carbs Go?
The truth, though, about low-carb assertions, is
much more complicated and entirely realistic. The
term ‘net carbs’ is really just creative
marketing terminology used to sell popular and
pleasantly textured and flavored foods as “low-carb.”
The FDA requires no testing or regulation of foods
marketed with these terms and does not approve the
expression. In fact, there are also dangers
associated with some low-carb foods, due to the way
manufacturers produce them. The artificial
sweeteners and sugar alcohols that are used to
replace the original carbohydrate content in the
foods are not absorbed… so where do they go? If
you consume more than 25-50 grams of sugar alcohols
in a day, you’ll find out it goes right through
you. Such products can have a significant laxative
effect when eaten in excess, and need to have a
laxative warning on the label. Sugar alcohols
aren’t digested or absorbed in the small
intestine, and are fermented in the large intestine,
which can cause gastrointestinal distress and/or
diarrhea. The carbohydrate goes right through you!
The only truly “Low Carb” foods that have little
to no sugar content are meats, nuts and seeds, some
cheeses, and creams.
Furthermore,
the initial and rapid weight loss (4-6 lbs.) that
followers of low-carb diets experience is almost
entirely from glycogen depletion and loss of water
weight. Each gram of glycogen (or carbohydrate
energy) in the body is stored with 3 grams of water.
So, each gram of carbohydrate energy, then, accounts
for 4 grams of body weight. By eliminating
carbohydrates from the diet, the body is forced to
burn through its stored glycogen. For a sedentary
person, this may take up to two days; for an
athlete, all it takes is a few hours. It is
important to know, though, that the water weight
lost during this time does not directly lead to
dehydration. The water lost is from muscle tissues,
not from other body tissues, organs, and blood
volume.
What
Does this Have to Do With Me?
Artificial
sweeteners and sugar alcohols certainly have their
place. They have allowed millions of diabetic
Americans to enjoy an increased variety of foods.
They have also allowed clinically obese people to
drastically cut back on overall calorie consumption
while still enjoying the satisfaction of good and
sweet tasting food on a regular basis. However, for
athletes, low-carb diets can be bad news.
Once
glycogen stores are depleted, the body seeks out fat
and protein sources for energy. First it turns to
protein, converting amino acids from muscle tissue
into glucose in the liver. This process is
relatively slow and can really only produce enough
carbohydrate to fuel your brain and nervous system.
When no relief comes from ingested carbohydrate, you
start producing ketone bodies (byproducts of fat
metabolism) and releasing them into the bloodstream.
As ketone levels increase, you enter a state of
ketosis, which suppresses the appetite, but can also
be accompanied by undesirable side effects, such as
nausea, headaches, fatigue, and breath that smells
like ammonia. Athletes on low-carb diets have
difficulty sustaining even moderate intensity
workouts of 50-65% of max heart rates when ketone
levels are elevated.
Although
low-carb diets and ‘net carb’ counting may have
their place for some people in society, it is clear
that these dietary practices are not appropriate for
athletes. The routine and guidelines for maintaining
the diet call for avoiding exactly what athletes
need: digestible, usable, and absorbable
carbohydrate that powers our muscles with energy.
Carbohydrate is the most versatile type of energy.
It feeds your brain and powers your muscles during
both anaerobic and aerobic metabolism. Carbohydrate
is the fuel that can be burned quickly, providing
the power for acceleration and high performance.
Ashley
Kipp is an elite coach and NASN Sports Nutritionist
at Carmichael Training Systems and a certified
Expert level cycling coach with USA Cycling. She
possesses a strong background in athletic
performance and has extensive experience in cycling,
distance and endurance training. She can be reached
at akipp@trainright.com.
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