Dieters on a low carb diet often hear a lot about ketones, but may not be sure what exactly these compounds are or how they affect the body. Ketones form during a low-carb diet as fat burning replaces carbohydrate burning in the body. They can be beneficial for weight loss but may be dangerous for some people. Understanding the connection between ketones and a low-carb diet can help you decide whether or not to try this type of diet.
Low Carb Diets
A low-carb diet features a carbohydrate level below about 20 percent of daily calories, typically in the range of 20 to 60 g of carbohydrates per day. Some modified low-carb diets include carbohydrate levels up to 30 percent of the daily caloric intake, typically under 150 g per day, but this is still far below the Acceptable Macronutrient Distribution Range, or AMDR, of 45 to 65 percent of calories recommended by the UDSA Dietary Guidelines for Americans. Individuals on a low-carb diet include more protein and fat in the diet to make up for the lack of carbohydrate calories.
Ketones
The body normally uses carbohydrates, broken down into the simple form glucose, for fuel to power everyday activity. When carbohydrate consumption is low, fat and protein are burned instead. Burning fat causes the release of compounds called ketones, or ketone bodies. This process is called ketogenesis. As ketones build up in the bloodstream, the blood becomes more acidic. Eventually, the brain begins to use ketones for fuel instead of glucose as ketone levels rise in the blood.
Benefits
As the body adapts to the rising levels of ketones in the blood, the dieter may experience a loss of appetite. This can help increase weight loss, since the dieter eats less food overall. Because of the breakdown in fat stores, the loss of appetite and a diuretic effect that causes water loss, individuals on a ketogenic low-carb diet often lose weight rapidly. A 2004 study in the journal "Experimental and Clinical Cardiology" also found that a low-carb ketosis-inducing diet lowered triglyceride, LDL and blood glucose levels.
Dangers
Individuals with pre-existing kidney disease should not use a low-carb diet that induces ketogenesis, since this type of diet can put stress on the kidneys. People prone to kidney stones and gout may develop these conditions when on a ketogenic low-carb diet. In healthy individuals, ketosis induced by a low-carb diet may cause dizziness, nausea, weakness and irritability.
References
- "American Family Physician"; Low Carbohydrate Diets; Allen Last, M.D., et al.; June 2006
- American Academy of Family Physicians; A Discussion of the Atkins Diet; Rebecca Kirby, M.D.; 2005
- "Annals of Internal Medicine"; The Impact of Protein Intake on Renal Function Decline in Women With Normal Renal Function or Mild Renal Insufficiency; E.L. Knight, et al.; March 2003
- "Experimental and Clinical Cardiology": Long-Term Effects of a Ketogenic Diet in Obese Patients; H.M. Dashti, et al.; 2004
- MayoClinic.com: Low-Carb Diet
- Dietary Guidelines for Americans 2005
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