Low Carbohydrate Diet

In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.


Since 1860, and more recently, in 1972, low carbohydrate (low-carb) diets have been a strategy for weight loss. Today, there continues to be an interest in low-carb approaches. While all low carbohydrate approaches reduce the overall intake of carbohydrates, there is no clear consensus on what defines a low-carb diet. There are three macronutrients—carbohydrates (4 kcal/gm), fat (9 kcal/gm), and protein (4 kcal/gm) found in food. Therefore, studies have defined low carbohydrate as a percent of daily macronutrient intake or total daily carbohydrate load. We will define it here as:

  1. Very low-carbohydrate (< 10% carbohydrates) or 20-50 gm/day

  2. Low-carbohydrate (<26% carbohydrates) or less than < 130 gm/day

  3. Moderate-carbohydrate (26%-44%)

  4. High-carbohydrate (45% or greater)

For reference, the Institute of Medicine proposes Americans obtain 45%-65% of calories from carbohydrates. This article will review the evidence and effectiveness of low-carb approaches in clinical medicine.

Publication types

  • Review