低碳水化合物饮食 （Low-carbohydrate diets或简化为Low-carb diets）是一系列通常用于控制体重或用于治疗糖尿病的限制碳水化合物摄入量的饮食方案。限制含可消化类碳水化合物高的食品（例如，面包、面条）或用含蛋白和脂类百分比高的食品（例如，肉类、禽类、贝类、蛋类、奶酪、坚果、植物籽实类、或花生）以及其他低碳水化合物的食品（如，大多数拌色拉的蔬菜）进行代替。低碳水化合物饮食也允许食用其他类蔬菜和水果（特别是浆果类）。不同的低碳水化合物饮食方案允许食用的碳水化合物的量不同。

Low-carbohydrate diets or low-carb diets are dietary programs that restrict carbohydrate consumption, often for the treatment of obesity or diabetes. Foods high in easily digestible carbohydrates (e.g., sugar, bread, pasta) are limited or replaced with foods containing a higher percentage of fats and moderate protein (e.g., meat, poultry, fish, shellfish, eggs, cheese, nuts, and seeds) and other foods low in carbohydrates (e.g., most salad vegetables such as spinach, kale, chard and collards), although other vegetables and fruits (especially berries) are often allowed. The amount of carbohydrate allowed varies with different low-carbohydrate diets.