Saturday, April 5, 2008

Low-Carb Concepts

Everybody's talking about carbohydrates, but what are they? And why does cutting back on them in your diet help you lose weight?

Let's start by understanding what carbohydrates are. Put simply, carbohydrates are the starchy or sugary part of foods. They're made up of long chains of molecules of carbon, hydrogen, and oxygen. Shorter, simpler chains of carbohydrates are sugars such as sucrose (table sugar), fructose (the sugar found in fruit), and glucose (the sugar that your body uses for fuel). Longer chains of carbohydrates are starchier and don't taste sweet -- these complex carbs are found in plant foods such as vegetables, beans, and grains. When you eat complex carbohydrates, your body quickly breaks them down into simpler sugars. (An easy way to prove this to yourself is to put a piece of plain white bread into your mouth and hold it there. You'll notice a slight sweet taste as digestive enzymes in your saliva begin to convert the bread into glucose.)

So, when your body digests carbohydrates, it converts them into glucose, which then enters your bloodstream. To carry the glucose from your blood into your cells, your body releases the hormone insulin. So far, so good -- but if you eat a diet high in carbs, the system doesn't work all that smoothly. Digesting the carbs puts a lot of extra glucose into your blood, which in turn mean you have to produce a lot of insulin to carry it into your cells. But if your cells have all the fuel they need for the moment, the extra glucose can't go into them. Instead, the insulin carries it off to be stored -- mostly as body fat.

For many people, eating a lot of refined carbohydrates -- foods such as white bread, snack foods, chips, french fries, sugary soft drinks, and all the other processed foods that take up so large a part of the typical diet -- does more than just make them gain weight. The simple sugars in refined carbs hit your bloodstream soon after you eat. Your body puts out a surge of insulin to deal with all that glucose, and you get a quick surge of energy. But for a lot of people, that insulin surge works all too well -- it clears away so much of the extra sugar that the energy surge is followed by an energy crash and feelings of hunger. What happens then? You reach for a candy bar or cookie for some more quick energy. It's a cycle of energy ebbs and flows that leads almost inevitably to putting on weight.

Here's where the low-carb approach comes in. First, you eliminate those refined carbohydrates from your diet and replace them with nutritionally dense whole foods. That means you're now eating a much healthier diet, because you've eliminated highly processed sugary or starchy foods that have little or no nutritional value. These foods can be high in salt and dangerous trans fats (you'll learn more about those later in this book), and they tend to crowd out more nutritious foods from your diet. Second, your blood sugar stays on a more even keel, giving you steady energy throughout the day. And third, you lose weight if you need to, because when you take away the carbs, your body burns fat for fuel instead.

If you need to lose weight, cutting carbs is almost certain to help. The approach works because you're replacing lowquality, high-calorie refined carbs with small amounts of high-quality carbs, along with plenty of fresh vegetables and other good low-carb foods, good fats, and high-quality protein. But how low do you need to go?

If you follow the approach taken by two of the leading low-carb diet doctors -- the late Dr. Robert C. Atkins and Dr. Arthur Agatston of South Beach Diet fame -- you'll start off by cutting your net carb count down to just 20 grams a day for the first two or three weeks. (Net carbs are the carbohydrates in a food minus the fiber -- Chapter Two of this book will explain this more.) After that, you'll slowly increase your daily carbohydrate intake. To continue losing weight, you'll probably have to keep your net carb count to under 60 grams a day. How your body responds to carbs is very individual, however. Some people will stop losing weight or even gain at just 40 grams of net carbs a day, while others can keep losing or stay at a steady weight at up to 100 or even 120 grams a day. Generally speaking, low-carbing means you're sticking to under 120 net carb grams a day (up to 150 grams a day for very active people), but you'll probably have to experiment a bit to find the level that's best for you.

To put all this in perspective, take a look at the typical carbohydrate counts for some commonly eaten foods:

1 slice white bread = 12 grams
8 ounces orange juice = 27 grams
5 Oreo® cookies = 55 grams
1 medium banana = 28 grams
1 12-ounce can cola soda = 27 grams
10 french fries = 16 grams

Is it any surprise that the average person takes in anywhere from 200 to 300 grams of carbohydrates a day? (When looking at these numbers, it helps to remember that there are roughly 15 grams in a tablespoon and about 30 grams in an ounce.) Unfortunately, many of those carb grams come from sugary or salty snacks that are high in calories but low in nutrition. In fact, Americans today get about one-third of their daily calories from snack foods. It's no wonder over half of all Americans today are overweight. By cutting back on carbs, you're almost automatically cutting back on the lowest-quality foods in your diet and substituting better foods such as fresh vegetables and protein.

Excerpted from

Net Carb Counter. Copyright © by Sheila Buff. Reprinted by permission of HarperCollins Publishers, Inc. All rights reserved. Available now wherever books are sold.
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