Low-carb diet: Can it help you lose weight?

Could a low-carb diet give you an edge in losing weight? Help you keep weight off permanently? Here's what you need to know about the low-carb diet. By Mayo Clinic Staff

A low-carb diet limits carbohydrates — such as grains, starchy vegetables and fruit — and emphasizes dietary protein and fat. Many types of low-carb diets exist, each with varying restrictions on the types and amounts of carbohydrates you can eat.

Purpose

A low-carb diet is generally used to lose weight. Some low-carb diets say that they have health benefits beyond weight loss, such as reducing risk factors associated with heart disease, certain cancers, diabetes and metabolic syndrome.

Why you might follow a low-carb diet
You might choose to follow a low-carb diet because you:

  • Want to change your overall eating habits
  • Enjoy the types and amounts of foods featured in low-carb diets
  • Want a diet that restricts certain carbs to help you lose weight

Check with your doctor or health care provider before starting any weight-loss diet, especially if you have any health conditions, including diabetes.

Diet details

As the name says, a low-carb diet restricts the amount of carbohydrates you can eat. Carbohydrates are a type of macronutrient found in many foods and beverages. Most carbohydrates occur naturally in plant-based foods, such as grains. Food manufacturers also add carbohydrates to processed foods in the form of starch or added sugar.

Common food sources of naturally occurring carbohydrates include:

  • Fruits
  • Vegetables
  • Milk
  • Nuts
  • Grains
  • Seeds
  • Legumes

Your body uses carbohydrates as its main fuel source. Sugars and starches are broken down into simple sugars during digestion. They're then absorbed into your bloodstream, where they're known as blood sugar (glucose). From there, the glucose enters your body's cells with the help of insulin. Some of this glucose is used by your body for energy, fueling all of your activities, whether it's going for a jog or simply breathing. Extra glucose is stored in your liver, muscles and other cells for later use or is converted to fat.

The theory behind the low-carb diet is that insulin prevents fat breakdown in the body by allowing sugar to be used for energy. Proponents of the low-carb diet believe that decreasing carbs results in lower insulin levels, which causes the body to burn stored fat for energy and ultimately helps you shed excess weight and reduce risk factors for a variety of health conditions.

Typical menu for a low-carb diet
In general, a low-carb diet focuses on proteins, including meat, poultry, fish and eggs, and some nonstarchy vegetables. A low-carb diet generally excludes or limits most grains, beans, fruits, breads, sweets, pastas and starchy vegetables, and sometimes nuts and seeds. Some low-carb diet plans allow certain fruits, vegetables and whole grains. A daily limit of 50 to 150 grams of carbohydrates is typical with a low-carb diet. Some low-carb diets greatly restrict carbs during the initial phase of the diet and then gradually increase the number of allowed carbs.

In contrast, the 2010 Dietary Guidelines for Americans recommends that carbohydrates make up 45 to 65 percent of your total daily calorie intake. So, if you consume 2,000 calories a day, you would need to eat between 900 and 1,300 calories a day from carbohydrates, or between 225 and 325 grams of carbohydrates a day.

Oct. 11, 2011 See more In-depth