Keto Diet

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Today’s topic is a ketogenic, or “keto” diet. Before getting into the diet, however, I would like to lay a little groundwork. Glucose, a simple sugar, is the fuel that powers our bodies. Usually, glucose is produced by the breakdown of starches, or carbohydrates. Once produced, glucose is transported into cells by insulin. The human body needs a constant supply of glucose in order to function. When there are no carbohydrates available to breakdown, the body will revert to breaking down fat, or fatty acids, to produce glucose. This occurs in the liver. A byproduct of the breakdown of fatty acids are ketone bodies, or ketones. For example, ketones may be detected in the urine of someone who is fasting. This is normal. A lack of insulin, for example in Type I diabetes, causes a buildup of glucose and ketones leading to a potentially life-threatening condition called ketoacidosis, but that is a topic for another day.

The keto diet restricts the daily carbohydrate intake to 5%, or about 25 to 50 grams. This is an attempt to force the body to burn fat to produce glucose, thereby causing weight loss and the production of ketones. This diet was first used in the 1920s to treat diabetes, before insulin was discovered. More recently, keto diets have been promoted as weight loss diets and to control blood glucose levels in prediabetic and diabetic patients. Keto diets may lead to short-term weight loss, but there is inconclusive scientific evidence that they are superior to other weight loss regimens in the long term. Claims of benefits of keto diets for cancer, dementia, and Parkinson’s disease are not supported by scientific evidence. Keto diets can result in weight loss for those who use this strategy to reduce overall caloric intake by limiting all carbohydrate-rich foods like breads, rice, pasta, cakes, cookies, and colas. Most fruits, legumes, and whole grains are also off limits. Foods that are acceptable include full-fat dairy products, meat and poultry, nonstarchy vegetables, olive oil, nuts and seeds, avocado, olives, and eggs. Long-term data is lacking on keto diets and cardiovascular and chronic disease risks. Low-carbohydrate diets have been linked to an increased risk of death.

When starting a keto diet, it is common to experience fatigue during exercise, increased hunger, sleep disturbances, muscle cramps, constipation, nausea, and stomach discomfort. Over the long term, a diet in which only 5% of total calories come from carbohydrates makes it impossible to obtain optimum amounts of antioxidant phytonutrients from fruits and vegetables. In the first two weeks of the diet, there may be significant increases in urine production and fluid shifts that may require adjustment of medications for hypertension, heart failure, and diabetes. Always consult with your physician before starting a ketogenic diet. Major diet changes should always be done under the supervision of a physician and a registered dietician.

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By Peter Galvin, MD

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