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Register for How I Got Skinny by Eating Fat or Why Low-Carb Works
by Adrienne Larocque, Ph.D.
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Your brain actually needs glucose for fuel, but your body is very intolerant of
changes in glucose levels. If you eat carbohydrates, you’ll experience a surge
in “blood sugar” (the concentration of glucose in your bloodstream), usually
peaking about 1 hour after you eat. To counteract the rise in blood sugar, a
hormone called insulin is released from your pancreas. Insulin has several jobs.
One is to help move glucose from the bloodstream into body cells to be used as
fuel. Insulin also converts some glucose into glycogen (a kind of starch) for
storage in your muscles and liver; this can be released quickly to provide
energy during exercise. If there’s more glucose than you need at any given time (i.e., during periods of low activity), insulin
converts the excess glucose to a fat called triglyceride and stores it.
That’s right. Even if you don’t eat fat, your body will make it from the
carbohydrate that you eat. That fat will be stored as adipose tissue, especially
around your waist. That’s exactly what happened to me. In August 2005, my best
friend told me that I looked like I was pregnant – but I wasn’t! Since cutting
down on the amount of carbohydrate that I eat, I don’t look pregnant anymore.
That’s because, simply put, you can’t store fat without insulin, and you won’t
have insulin circulating in your bloodstream if you don’t eat carbohydrate. And
if you exercise, you’ll burn fat that you have already stored. Of course if you
eat fat and carbohydrate together (e.g., French fries), you will store both the
excess glucose and the fat!
Dietary protein and fat can provide energy for your body, but they don’t raise
the concentration of glucose in your blood like sugar and starch do, and so
insulin is not released from the pancreas. Proteins are large, complex molecules
made up of amino acids. Amino acids are like beads; if you string them together,
they make a protein molecule. There are 20 amino acids used by your body; 8 of
these are considered “essential” in the diet because they can’t be made or
stored by your body and therefore you must eat them every day. The body also
needs, but cannot make, essential fatty acids; these are the building blocks of
fat molecules.
Unlike carbohydrates, proteins and fats have other (non-fuel) functions in the
body. There are many, but one of the most important is in the growth, repair and
maintenance of cells. Every cell in your body has an outer layer called a cell
surface membrane that controls what goes in and out of the cell (things like
water and nutrients, but also bacteria and viruses). Each cell membrane is made
of a double layer of fat with protein bodies distributed here and there. Both
amino acids and fatty acids are necessary for the manufacture of hormones in the
body. Antibodies, which fight bacteria and viruses, are specialized blood
proteins. So in addition to supplying you with energy, fat and protein provided
the building materials to keep your body functioning properly. Carbohydrates
don’t do this.
Whenever I talk about limiting the amount of carbs that you eat, someone always
says “But you need carbohydrate for energy!” While it’s true that your brain
relies on glucose for its fuel, you don’t need to eat carbohydrate to keep your
blood sugar at the correct level. The best illustration of this is the fact that
the traditional diet for people living near the Arctic Circle in Europe, Asia
and North America consisted almost entirely of meat and seafood, with no
carbohydrate. They survived because the body can actually make glucose by
breaking down the building blocks of protein and fat.
Most people don’t really have a clear idea about what foods contain carbs. For
example, many people I’ve spoken with think that fruits don’t have any, possibly
because they’ve heard mainly about “complex carbohydrates” in grains. The
sidebar summarizes the main food sources of carbohydrates; note that this list
was compiled by Dr. Bernstein for his diabetic patients. I actually eat many of
the foods on the list, but I eat small portions of them, and if possible, I
schedule them just before I work out; I no longer eat ANY rice, noodles or
potatoes, and I rarely eat any bread. These foods definitely should not be eaten
just before bedtime or other periods of low activity. Some of the items on the
list are obvious no-no’s (such as cakes and candies), but you may surprised by
others (who knew about tomatoes?)!
OK, so now that you know what NOT to eat, you might ask “What’s left?” It’s
actually pretty simple. For energy, eat food that comes from animals: meat
(beef, pork, lamb, goat), poultry and eggs, fish and seafood, and some dairy
products (cheese, butter). In addition to protein, animal sources contain fat
which, as I explained above, your body actually needs. The list of foods that I
eat is short, but I don’t feel deprived because I can eat a lot of any of them
and not gain weight. In contrast, carbs actually make you hungry because they
rob your body of energy, at the same time that they make you gain weight.
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