We have been watching the low carb controversy for many
years--many of us--professionals with diabetes--understood that carbs were the
enemy and tried, at least somewhat, some more and some less, to curb the
amounts and types of carbs in our diet and kept an eye on the glycemic index of
foods. How we tought our patients depended very much on their needs and
capabilities and how many carbs and how much fat, and which fats, depended on
which school we came from.
But at last, a lot has changed and it is now becoming accepted
that carbs are the enemy of this generation. Carbs are what is making us
fat and carbs are making us sick---again how much varies.
But I am pleased to bring this study to your attention--it is not
strongly advocating low carbs but explaining its virtues very well.
A professor of biochemistry provides perspective.
Heres an idea to chew on: The carbs in your diet tell your body
what to do with the fat you eat, so its the type and amount of carbohydrates
that matter when it comes to your weight and health.
Virtually every bit
of health information today includes the advice to avoid saturated fat the
so-called evil stuff that lurks in animal foods like steak and eggs. The basis
for this recommendation is that research has shown a correlation between
saturated fat intake and total cholesterol and LDL (bad cholesterol). The
problem with these studies is that the effects are not large, there is wide
variation among individuals and, in most of these studies, the predicted benefit
in incidence of cardiovascular disease did not materialize. In addition, we now
know much more about risk factors for cardiovascular disease (CVD) beyond LDL.
No assessment of CVD risk can be made without considering HDL (good
cholesterol), triglycerides, and the size of the LDL particle. Plenty of
research shows that these markers can worsen when people reduce their intake of
saturated fat and that they can improve by reducing the intake of carbohydrates.
You dont have to be a medical researcher to recognize that this is a
politically charged issue. The thing that is missing for the public is an
impartial evaluation of all the data on saturated fat. My personal opinion is
that there is much contradictory data and a recent review of the situation
suggests that there is not sufficient evidence to make any recommendations.
There is a sense that, in the absence of definitive evidence, lowering
saturated fat will at least do no harm. This is not right. The problem for
people with diabetes is what happens when saturated fat is replaced with
carbohydrate, and research has repeatedly shown that this may actually be
harmful. Consider that, according to the Centers for Disease Control and
Prevention, during the onset of the current epidemic of obesity and diabetes,
almost all of the increase in calories in the American diet has been due to
carbohydrate. The percent of total fat and saturated fat in our diet decreased.
In men, the absolute amount of saturated fat consumed decreased by 14 percent!
One of the most striking reasons to doubt the across-the-board
proscriptions against saturated fat is the report from the large scale
Journal of the American Medical Association, titled Inverse association
of dietary fat with development of ischemic stroke in men. You read that right:
The more saturated fat in the diet, the lower the incidence of stroke.
Perhaps the most compelling research was published in a 2004 issue of
the American Journal of Clinical Nutrition by researchers from the
Harvard School of Public Health. Their study showed that, in postmenopausal
women with heart disease, a higher saturated fat intake was associated with less
narrowing of the coronary artery and a reduced progression of disease. Even with
similar levels of LDL cholesterol, women with lower saturated fat intake had
much higher rates of disease progression. Higher saturated fat intake was also
associated with higher HDL (the good cholesterol) and lower
If saturated fat isnt the problem, what is?
this study, in which greater saturated fat intake was associated with less
progression of coronary atherosclerosis, carbohydrate intake was associated with
a greater progression. Carbohydrate, through its effect on insulin, is the key
player. Insulin not only sweeps up glucose from the blood but it also plays air
traffic controller, making the call as to whether that glucose is turned into
fat or is used for energy. Most importantly, insulin determines what happens to
dietary fat whether it gets stored or oxidized for fuel. In fact, insulin has
so much control over how dietary fat is metabolized that funny pictures when levels of fat are
measured in the blood, they are not strongly associated with a person's diet. In
other words, one person who has a high intake of saturated fat may turn out to
have a similar ratio of saturated to unsaturated fat in the blood as someone who
consumes very little saturated fat.
A recent study by Jeff Volek at the
low-carbohydrate and low-fat diets. Even though the low-carbohydrate diet had
three times as much saturated fat as the low-fat diet, levels of unhealthy fats
in the blood were lower in the low-carbohydrate group. How is that possible?
That is what metabolism does.
What is the best diet?
know the ideal diet composition. We do know that saturated fat, unlike
trans-fat, is a normal part of body chemistry and extreme avoidance is not
justified by current scientific data. Removing some saturated fat to reduce
calories is good, but adding back carbs appears to be deleterious. It appears
that healthy, carbohydrate restriction will trump the effects of any kind of
fat. For a person with diabetes, blood glucose must be the first consideration.
If you have relatively tight blood sugar control, the amount of saturated fat
you eat may be a non-issue. You can do what we did before the diabetes-obesity
epidemic: regulate your intake by your taste and your natural appetite. No one
ever did want to eat a pound of bacon.
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