The Truth About Carbs
Allison Tannis, BSc, MSc
North America is facing the largest change in dietary perception it’s seen in two
decades. This change is enormous and it causing food manufactures to restaurants to alter
the way they offer food. Advertisements for non-food items are even joking about how
their product fits into the new dietary ideal. This phenomenon is an enormous swing in
dietary rules and has the continent buzzing. The low-carb diet has engulfed our society.
In the 1980s we were invaded with the low fat diet. It stemmed from two major
thoughts. Firstly, when we are unhappy with our appearance we tend to describe
ourselves as fat. This lead many to believe that dietary fat equaled body fat. However, it
is important to mention that your body will create fat regardless of if you eat it or not.
More importantly, consumption of fat in you diet does not necessarily mean you will be
overweight. Your weight is part of a complicated equation of your dietary intake, output
and your own personal metabolism rate. Secondly, scientific studies started noting the
association between a high fat diet and disease. In particular, scientists were noting that a
high fat diet can increase the risk of cardiovascular disease and colon cancer.
The 1980s was a decade of dietary change. Everything on store shelves were
screaming “low fat” from their labels. People would buy low fat brownies, even if they
had not bought brownies before, because consumers believed that low fat meant healthy.
Therefore, the desire for low fat foods drove the market. The Food Guides of Canada and
the United Stated reflected this as fats and oils were placed at the top of the pyramid, and
dietary intake was limited. Unfortunately, there was no division in peoples minds about
good and bad fat. The truth about fats will be discussed more in Chapter 4.
Through the 1990s we demanded more low fat foods, and emphasized a need for
convenience as our lives became busier. Taste and convenience quickly toped the dietary
needs of consumers – not nutrition. As our diets began to lack fat, we replaced this high
caloric group of nutrients with carbohydrates. Pasta, pizza, and bake yourself breads and
pastries flooded the market place.
However, the whole idea of the low fat diet was to loose weight. But, we’re not.
In fact, the percentage of Americans who are overweight has jumped from 55.9% to 64.5
% in the last decade. So, we are eating less fat, but getting fatter. The war on obesity is
not being won.
Why exactly we are now drowning in high protein/low carbohydrate diets and
their promises of quick and easy weight loss is not clear. However, with an estimated
300,000 deaths associated with obesity each year in the United States there is a great need
in society to find an effective way to loose weight. In fact, an estimated ¾ of our
population is currently using a low carbohydrate diet. It appears that a majority of the
population feels that a low carbohydrate diet is a good way to loose weight. Thus, we are
being engulfed with the low-carb phenomenon that is changing the dietary mindset of the
continent.
The recent trend of high protein, high fat diets has the continent divided. There
have been many diets, since the 1960s that have suggested a high protein diet for weight
loss. These diets tend to incorporate a limitation of carbohydrates. Some of these high
protein diets include the Atkins diet, the Zone diet and the Stillman diet. Most popular of
late, is the Atkins diet, whose fundamental theories have been altered and manifested into
an anti-carb society. It’s time to lose weight. With over half of North Americans
believing that the low carb trend will last forever (Grocery Manufacturers of America
Survey, 2003) it is urgent that we uncoverunveil the truth about carbs.
Perhaps is all started in the 1970s when Dr. Atkins first suggested a high protein diet for
weight loss. Such a high protein diet involves restrictions on carbohydrate intake. Today,
high protein/low carbohydrate diets (i.e. Atkins diet, the South Beach Diet, the Stillman
diet) are flooding North America. Most popular of late, is the Atkins diet, whose
fundamental theories have been altered and manifested from a high protein diet into an
anti-carb/no-carb society. It’s like the childhood game telephone, where the original
message is gibberish by the time it reaches the final listener.
Recent surveys in North America indicate that the low carb diet is here to stay. In fact,
the Grocery Manufactures of America Survey indicated that 82% of respondents believe
that the low carb trend will last, with 51% saying that it will last forever. The survey also
noted that 74% of respondents were following a low carb diet, and 40% plan to eat more
low carb foods in 2004. Therefore, a majority of the population of North America feel
that a low carbohydrate diet is a good way to lose weight. This may be associated with
the appealing satiety of a high fat diet. However, high protein dieters are missing many
of the facts.
The truth about carbohydrates has been lost in the many media messages. As an example
we’ll use Dr. Robert Atkin’s diet as described in Atkins for Life. This diet is founded on a
well balanced diet that cuts out white, processed foods and encourages high fibre foods
and protein. As most North Americans have a low consumption of protein (e.g. men 8892g, women 63-66g), encouraging protein consumption is not a bad suggestion,
particularly when nuts, fish and soy are encouraged as protein sources. The suggestion to
cut out white, processed carbohydrates is also good nutritional advice.
The great need of North Americans to find a quick way to lose weight may be blinding
them from some of the facts about carbohydrates. With an estimated 300,000 deaths in
the United States associated with obesity each year, and the percentage of overweight
Americans jumping from 55.9% to 64.5% in the last decade - the war on obesity is
intensifying.
The theory of reducing the use of white/processed carbohydrates is based on the glycemic
index – a measurement of how easy a carbohydrate is digested by the body into glucose
(i.e. sugar). Highly processed foods have a high glycemic index because they consist of
simple carbohydrates. Simple carbohydrate are quickly digested it into glucose causing a
quick, rapid rise in blood glucose levels, and a mirroring insulin response. Insulin
encourages cells use glucose immediately or, to store it as fat. This quick rise and quick
removal of sugar in the blood happens in a short period of time, and leaves you hungry
shortly after you ate the high glycemic food despite sufficient caloric intake. Therefore,
high glycemic index foods can result in over eating and have been suggested to be
associated with obesity.
The truth about carbohydrates has been lost in the many media messages. It’s like a game
of telephone gone wrong. As an example we’ll use Robert Atkin’s book, Atkins for Life.
In this book, the foundation of the Atkins diet is explained. The foundation is a well
balanced diet that cuts out white, processed foods and encourages high fibre foods and
protein. As most North Americans have a low consumption of protein (e.g. men 88-92g,
women 63-66g), encouraging protein consumption is not a bad suggestion, particularly
when nuts and soy are encouraged as protein sources. Chicken, fish and egg whites are
also good sources of protein in a healthy diet.
Meanwhile, complex carbohydrates have a low glycemic index because they are harder to
digest (i.e. breakdown) into glucose. So, your glucose rises more slowly, your insulin
removes the glucose slowly, resulting in a longer time period before your blood glucose
lowers enough to stimulate hunger. Therefore, avoiding high glycemic foods theoretically
means less overeating, reduced obesity, and perhaps even weight loss. This suggests that,
a diet low in white/processed carbohydrates has some healthy foundation. The theory of
reducing the use of white/processed carbohydrates is based on the glycemic index – a
measurement of how bad a carbohydrate is for the body. Highly processed foods such as
white bread and cereal like sugar pops, are mostly simple sugar, also known as simply
carbohydrates. These foods have a high glycemic index (i.e. they cause a high peak in
glucose shortly after consumption). The result of a high glucose peak, is a resulting
insulin response, which causes the quick storage of glucose (e.g. fuel), and a resulting
hunger despite sufficient caloric intake. Therefore, high glycemic index foods can result
in over eating and have been suggested to be associated with obesity. On the other hand,
whole wheat products are mostly fibre, also known as complex carbohydrates which do
not challenge the body as much and therefore have a low glycemic index.
However, the nutritional science behind high protein/low carbohydrate diets is such a diet
is questionable. There are three nutritional concerns with the manifested anti-carb/low
carb diet that has evolved: the high protein consumption; the high consumption of bad
fat; the lack of needed carbohydrates and essential vitamins and minerals. The claimed
reason for choosing high fibre and high fat diets is that the fat slows the absorption of
glucose into the blood stream, reducing satiety. However, a high fat diet can have many
negative effects on the body, including gastrointestinal problems, liver and kidney strain
from excessive protein and fat metabolism needed, colon disease and cardiovascular
disease.
Creators of high protein diets argue that choosing a high fat diet, is good as fat slows the
absorption of glucose into the blood stream, reducing satiety. However, a high fat diet
can have many negative effects on the body, as it is a well known fact that a diet high in
fat is associated with disease, particularly cardiovascular disease.
High protein diets are based on good nutritional concepts such as reducing high glycemic
foods and increasing protein in our diets. However, the result can be a reduced or
complete elimination of needed carbohydrates, a great increase in fat consumption and a
resulting vitamin, mineral and essential fatty acid deficiency. The scientific research on
high protein diets suggests that we all take a closer look at this trend.
A high protein diet may have negative physiological impacts. High protein consumption
can result in increased production of uric acid in the body, which canThe weight loss
experienced with high protein diets is wrongly associated with the elimination of
carbohydrates. The weight loss in high protein diets is initially high due to fluid loss
related to reduced carbohydrate intake (sodium and water loss), glycogen depletion,
overall caloric reduction, and ketosis-induced appetite suppression. The resulting
beneficial blood lipids and insulin reduction is due to the weight loss, not the change in
caloric consumption. Furthermore, the change in diet and weight loss cause gout.
(Framzese et al. 2000) Highmetabolic changes the reduce insulin levels, however,
protein consumption can also cause an increase in calcium loss through the
urinestimulates insulin secretion (Diabetes Nutr Metab 1999), therefore increasing the riskbe
wary of osteoporosis. (J Nutr 1998) Also, a diet rich in animal this claimed health benefit
with high-protein, saturated fat, and cholesterol has been shown in a human trial to raise
low density lipoprotein (LDL) cholesterol levels, an effect that is compounded by the
lack of high fibre, high carbohydrate plant foods that can lower cholesterol. (J Am Diet
Assoc 1980) Despite noted weight loss, the rise in LDL is concerning as it’s associated
with a greater risk of cardiovascular disease. The lack of carbohydrates, such as fruits and
vegetables, may also increase the risk of heart disease. (J L ab Clin Med 1986; Am J Clin Nutr
1986; J Am Diet Assoc 1980, N Engl J Med 1997) Furthermore, to metabolize and eliminate the
by products of extra protein in the diet, the liver and kidneys have to work very hard and
may speed the progression of diabetic renal disease. (Lancet 1989) Therefore, high protein
consumption may compromise bone, joint, heart, liver and kidney health diets.
A diet that lacks carbohydrates, is like a car that lacks gas. Carbohydrates are our fuel.
We need them. A lack of carbohydrates in the diet results in the use of glycogen stores in
the muscle which are used to sustain extended use of muscles. Therefore, a high protein
diet may result in early fatigue during exercise. Perhaps more importantly, restrictions on
carbohydrate consumption can result in the loss of lean muscle tissue. (Sports Med 1992).
We’ve discussed that some carbohydrates are better than others. Complex carbohydrates
are part of a healthy diet. In particular, restricting fruits and vegetables may have negative
health effects, as such a diet would lack needed vitamins and minerals. Also, a restriction
in fruits and vegetables can mean an increase in the risk of cancer, as countless research
studies have noted their anti-cancer protecting effects. (Am Inst Cancer Res 1997)
Ketosis, is the break down of fat as fuel. This is great in theory, however excessive
ketosis in the body can result in negative results, such as elevated nonessential fats in the
blood stream, kidney stones, dehydration, and osteoporosis.
Now, the truth about weight loss. The weight loss experienced with high protein diets is
wrongly associated with the elimination of carbohydrates. The weight loss in high protein
diets is initially high due to fluid loss related to reduced carbohydrate intake (sodium and
water loss), glycogen depletion, overall caloric reduction, and ketosis-induced appetite
suppression. Ketosis, is the break down of fat as fuel. This is great in theory, however
excessive ketosis in the body can result in negative results, such as elevated nonessential
fats in the blood stream, kidney stones, dehydration, and osteoporosis. According to
current scientific research the only healthy and sustainable way to loose weight is a
caloric deficit of 500kcal/day. (Circulation 2001)The increase in dietary protein has
negative physiological impacts. Firstly, a diet rich in animal protein, saturated fat, and
cholesterol raises low density lipoprotein (LDL) cholesterol levels, an effect that is
compounded by the lack of high fibre, high carbohydrate plant foods that can lower
cholesterol. This potential negative health effect was shown in a human trial that had
subjects use a high-protein diet for 3 months. (J Am Diet Assoc 1980) The subjects
experienced raised LDL levels despite weight loss.
A meta-analysis of scientific studies on low carbohydrate diets concluded that there is
insufficient evidence to make recommendations for or, against the use of lowcarbohydrate diets. They continued to state that “among the published studies, participant
weight loss while using low-carbohydrate diets was principally associated with decreased
caloric intake and increased diet duration but not with reduced carbohydrate content.”
Therefore, reducing carbohydrates may not be the cause of weight loss.
Secondly, a diet high in carbohydrate foods (fruit, vegetables, nonfat dairy products,
whole grains) has been shown to lower blood pressure. Therefore the restriction of these
foods in the high-protein diet further compromises the health of the cardiovascular
system. The potential raise in blood pressure can be associated with the limited intake of
potassium, calcium, and magnesium, coupled with an increase in sodium intake.
(McDowell et al, 1991; In J Cancer 1975, J Lab Clin Med 1986; Am J Clin Nutr 1986; J Am Diet Assoc
1980, N Engl J Med 1997)
What is the truth about carbs? The truth is that we need carbohydrates. They are our fuel.
However, some carbohydrates are better than others. High fibre and whole wheat choices
are always best. Avoid white breads, white sugar and juices as these can cause high
glucose peaks in the blood stream. Try to focus on high nutritional quality foods in your
diet and enjoy health.
Also…
 A high protein consumption can result in an increase in uric acid (i.e. a
metabolite of purine breakdown) which can cause gout. (Framzese et al. 2000)
 A protein surplus can also cause an increase in calcium loss through the urine,
therefore increasing the risk of osteoporosis. (J Nutr 1998)
 A restriction in fruits and vegetables can mean an increase in the risk of cancer,
as countless research studies have noted their anti-cancer protecting effects. (Am
Inst Cancer Res 1997)
 To metabolize and eliminate the by products of extra protein in the diet, the liver
and kidneys have to work very hard. High protein diets may speed the progression
of diabetic renal disease (Lancet 1989), so diabetics beware.
High protein diets generally mean a low carbohydrate diet. However, the lack of
carbohydrates in the diet results in the use of glycogen stores in the muscle which are
used to sustain extended use of muscles. Therefore, a high protein diet may result in early
fatigue during exercise (Sports Med 1992). Perhaps more importantly, restrictions on
carbohydrate consumption can result in the loss of lean muscle tissue.
A meta-analysis of all studies that have investigated low carbohydrate diets concluded
that there is insufficient evidence to make recommendations for or against the use of low-
carbohydrate diets. They continued to state that “among the published studies, participant
weight loss while using low-carbohydrate diets was principally associated with decreased
caloric intake and increased diet duration but not with reduced carbohydrate content.”
Therefore, reducing carbohydrates probably does not cause weight loss, at least not in the
long term.
Perhaps the most important fact about high-protein diets is the lack of essential nutrients.
The reduction of fruits and vegetables can result in deficiencies in many vitamins and
minerals. In fact, supplementing with multi vitamins and minerals is a part of the Atkins
diet.
The great importance of essential fatty acids is also mentioned and included as part of the
Atkins diet. These are good fats, and are a vital part of a healthy diet as they improve
cardiovascular, cognitive, and glucose metabolism and can reduce the risk of cancer.
Supplementing with a multi-EFA, or incorporating fatty fish (e.g. salmon, tuna,
mackerel), flax, soy and omega-3 eggs to your diet are great ways to reap the benefits of
these good fats.
All in all, the scientific literature suggested that there are some serious issues with higprotein diets. Firstly, there are no scientific studies to suggest the potential long term
effects of such a diet. However, a high protein diet may impose burden on the kidneys
and liver, and likely increases the risk of coronary heart disease. Caloric deficits of
500kcal/day, or a steady weight loss of 1lb a week is healthy and sustainable according to
current scientific research. (Circulation 2001)
Therefore, what can we conclude? What is the truth about carbs? The truth is that we
need carbohydrates. They are our fuel. However, some carbohydrates are better than
others. High fibre and whole wheat choices are always best. Avoid white breads, white
sugar and juices as these can cause high glucose peaks in the blood stream. Try to focus
on high nutritional quality foods in your diet. Therefore, whole wheat foods, vegetables
and protein sources such as chicken, fish, eggs, nuts and soy. Also, remember that your
body needs supplements such as a multi vitamin, and a multi EFA.
Further Reference:
Sachiko et al. 2001. Dietary Protein and Weight Reduction. Circulation. 104:1869-74.