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 those found in grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat. Many types of low-carb diets exist. Each diet has varying restrictions on the types and amounts of carbohydrates you can eat.

Purpose

A low-carb diet is generally used for losing weight. Some low-carb diets may have health benefits beyond weight loss, such as reducing risk factors associated with diabetes and metabolic syndrome.

Why you might follow a low-carb diet

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

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

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

Diet details

As the name says, a low-carb diet restricts the type and amount of carbohydrates you eat. Carbohydrates are a type of calorie-providing macronutrient found in many foods and beverages.

Many carbohydrates occur naturally in plant-based foods, such as grains. In natural form, carbohydrates can be thought of as complex and fibrous such as the carbohydrates found in whole grains and legumes, or they can be less complex such as those found in milk and fruit. Common sources of naturally occurring carbohydrates include:

  • Grains
  • Fruits
  • Vegetables
  • Milk
  • Nuts
  • Seeds
  • Legumes (beans, lentils, peas)

Food manufacturers also add refined carbohydrates to processed foods in the form of flour or sugar. These are generally known as simple carbohydrates. Examples of foods that contain simple carbohydrates are white breads and pasta, cookies, cake, candy, and sugar-sweetened sodas and drinks.

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). Fiber-containing carbohydrates resist digestion, and although they have less effect on blood sugar, complex carbohydrates provide bulk and serve other body functions beyond fuel.

Rising levels of blood sugar trigger the body to release insulin. Insulin helps glucose enter your body's cells. Some 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 usually stored in your liver, muscles and other cells for later use or is converted to fat.

The idea behind the low-carb diet is that decreasing carbs lower insulin levels, which causes the body to burn stored fat for energy and ultimately leads to weight loss.

Typical foods 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, legumes, fruits, breads, sweets, pastas and starchy vegetables, and sometimes nuts and seeds. Some low-carb diet plans allow small amounts of certain fruits, vegetables and whole grains.

A daily limit of 60 to 130 grams of carbohydrates is typical with a low-carb diet. These amounts of carbohydrates provide 240 to 520 calories.

Some low-carb diets greatly restrict carbs during the initial phase of the diet and then gradually increase the number of allowed carbs. Very low-carb diets restrict carbohydrates to 60 grams or less a day.

In contrast, the Dietary Guidelines for Americans recommend 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.

Sep. 18, 2014 See more In-depth