Low-carbohydrate diets may do wonders for quick weight loss (mostly from water loss) and to improve glucose and insulin levels, but they are not without their adverse effects (1-2).
The body needs carbs for energy. Without sufficient amounts, muscle catabolism and protein will result, the break down of fat stores for fuel will result in incomplete fat oxidation, and an excess of acidic ketones will be produced. Diets too low in carbs can lead to ketoacidosis (1).
However, moderately low-carb diets such as the Mediterranean diet, which includes plenty of fruits, vegetables and monounsatured oils are a good choice for long-term health (2).
1. Nix, S. (2005). Williams' Basic Nutrition & Diet Therapy. Philadelphia: Mosby.
2. Shai, I., Schwarzfuchs, D., Yaakov, H., Sahar, D.R., Witkow, S., et al. (July, 2008). Weight loss with a low-carbohydrate, Mediterranean or low-fat diet. The New England Journal of Medicine, 359:229-241.