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.
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 type 2 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 before starting any weight-loss diet, especially if you have any health conditions, such as diabetes or heart disease.
As the name says, a low-carb diet restricts the type and amount of carbohydrates you eat. Carbohydrates are a type of calorie-providing macro-nutrient found in many foods and beverages.
Carbohydrates can be simple or complex. They can further be classified as simple refined (table sugar), simple natural (lactose in milk and fructose in fruit), complex refined (white flour) and complex natural (whole grains or beans).
Common sources of naturally occurring carbohydrates include:
- Legumes (beans, lentils, peas)
Food manufacturers also add refined carbohydrates to processed foods in the form of sugar or white flour. Examples of foods that contain refined carbohydrates are white breads and pasta, cookies, cake, candy, and sugar-sweetened sodas and drinks.
Your body uses carbohydrates as its main fuel source. Complex carbohydrates (starches) are broken down into simple sugars during digestion. They’re then absorbed into your bloodstream, where they’re known as blood sugar (glucose). In general, natural complex carbohydrates are digested more slowly and they have less effect on blood sugar. Natural 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 lowers 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 0.7 to 2 ounces (20 to 60 grams) of carbohydrates is typical with a low-carb diet. These amounts of carbohydrates provide 80 to 240 calories. 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 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.