How a Low Carb Diet Works

Low carb diets restrict pasta, breads and starchy vegetables, like potatoes.
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As the name implies, a low-carb diet limits all sources of carbohydrates -- grains, starchy vegetables, fruits and dairy products -- in your diet. There are different types of low carbohydrate diets, some you're probably very familiar with, and each varies on how many and what types of carbohydrates you can eat; however, the basic goals -- usually weight loss -- and principles are the same.

Metabolism of Carbohydrates

Your body uses carbohydrates for energy -- running, jumping, wrestling with the kids when you're trying to get them to go to bed, whatever. During digestion, your body breaks down sugars and starches in carbohydrates into glucose -- the simplest form of sugar. Glucose moves into your blood, and tells -- well, signals -- to your pancreas to release insulin, a hormone. Insulin carries glucose into your cells, where some of it is used immediately for energy, some is stored in your liver and muscles and the rest is converted to -- you guessed it -- fat.

How a Low Carb Diet Works

The theory behind a low-carbohydrate diet is that the glucose/insulin reaction prevents you from breaking down fat and using it for energy. When you give carbohydrates the boot, you allow your body to turn to burning fat, which contains 9 calories per gram, for energy. This is called ketosis. Proponents of low-carb diets say that when you’re in ketosis, you feel less hungry and, as a result, you don't want to pig out.

Diet Details

Proteins such as chicken, meat, shellfish, fish and eggs, along with fat, are the foundation of low-carb diets. Low-carb diets restrict or completely eliminate carbohydrate-containing foods such as pasta, potatoes, rice, bread, sweets, fruits and starchy vegetables such as potatoes. The exact number of carbohydrates you can have depends on which specific diet strikes your fancy, but most low-carb diets allow somewhere between 50 to 150 grams of carbohydrates per day. Some low-carb diets start with an initial phase that allows barely any carbohydrates and then gradually increase the number of allowed carbs as you solider on.


The Food and Nutrition Board -- the part of the Institute of Medicine that sets nutrition recommendations – suggests getting more than half of your calories, or 55 to 65 percent, from carbohydrates. Some low-carbohydrate diets restrict carbohydrates to a measly 10 percent, or less, of daily calories. If you decide to follow a low-carbohydrate diet, choose one that focuses on healthy carbohydrates like beans, fresh fruit, vegetables and whole grains, rather than one that makes you get rid of carbohydrates completely. It should also focus on heart-healthy fats like olive oil and avocados, and healthy proteins such as fish and skinless chicken. Also, remember that low-carb doesn’t always mean low-calorie.

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