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Low-Carb Ketogenic Diets Burn Fat
Low-Carb Ketogenic Diets Burn Fat
Mention “high-protein, low-carbohydrate diet” to most people, and the rise and fall of the beef- and bacon-filled menu of the Atkins plan will likely come to mind. And while it’s true the Atkins’ diet had plenty of critics and is now no longer considered in vogue, such ketogenic diets are still being used to rapidly reduce body fat, as well as to address a number of health conditions including diabetes and epilepsy.
By definition, a ketogenic diet is one that drastically restricts carbohydrates—usually to less than 100 grams per day—and emphasizes protein and fat. Restricting all carbohydrates—everything from bread to beans—depletes the amount of glucose available, which is normally the body’s go-to energy source. In response, the body looks for another source of fuel, such as fat stores.
Ketosis is the process of metabolizing or breaking down fat for fuel, which mainly happens in the liver. Water-soluble ketone molecules are produced and released into the bloodstream, and most of them are useable as fuel for the heart, brain and other organs. Those that aren’t used are simply excreted. In other words, when your body reaches ketosis, you’re both burning fat and expelling it out of your body. And if that isn’t enough, individuals on a ketogenic diet often have less of an appetite. This added benefit is likely due to the fact that protein plays a major role in how quickly one feels full, and therefore how quickly one feels hungry again.
With results like this, it’s no wonder ketosis is often the diet of choice for professional bodybuilders approaching competition or people just wanting to get lean in rapid time, say for their wedding day. And as long as you are eating adequate quantities of protein and calories, your body should preserve muscle mass and simply drop fat instead, along with water weight, says Derek Johnson, a Los Angeles-based holistic nutritionist and executive nutrition director of the Biggest Loser Resorts. “I also recommend people on ketogenic diets eat lots of greens to keep their body from becoming too acidic,” he says.
If ketosis sounds like a miracle weight-loss method, in most regards it is. However, it’s generally best used only in the short-term, recommends Johnson. First, because it’s often challenging to eat so few carbohydrates, but more importantly because it can trigger a few health concerns. The most benign of these is a bit of fatigue and brain fog during the first few weeks of ketosis when the body is learning to shift its fuel source from glucose to ketones. Once efficient at manufacturing ketones, though, people often report having increased energy and fewer of the blood sugar highs and lows that can result from eating carbohydrates.
Of bigger concern is what replacing all those carbohydrates with protein and fat sources does to one’s blood lipid profile. Apparently the answer depends on just what kind of fat and protein you choose. A study in the July 2002 issue of the Journal of Nutrition showed that in the short term, even a ketogenic diet heavy in red meat, butter and cream often results in an improvement in cardiovascular markers. But according to a study published in the September 2010 issue of the Annals of Internal Medicine, the long-term effects of eating a low-carbohydrate diet based on such animal sources was associated with higher all-cause mortality in both men and women, whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.
The most dangerous health issue associated with a ketogenic diet is ketoacidosis, a condition in which the level of ketones in the blood rises out of control, causing high blood sugar and dehydration and lowering the pH of the blood to a critical level. Though this situation can be deadly for type 1 diabetics, it is generally not a serious threat for healthy dieters, as the body has several mechanisms that prevent ketoacidosis from occurring. “The key is to make sure you are not allowing the body to get too acidic,” says Johnson. “Eat lots of greens, not just protein.”
The risk of too many ketones in the body may be a very dangerous proposition for those with type 1 diabetes, but ketogenic diets have actually been shown to be safe and very effective methods for treating type 2 diabetes. For example, a study published in the December 2005 issue of Nutrition and Metabolism demonstrated that when participants with type 2 diabetes were put on a low-carbohydrate, ketogenic diet (less than 20 grams of carbs per day) for 16 weeks, glycemic control was so improved that most participants discontinued or reduced diabetes medications.
Even more impressive are the results of using an extreme version of the ketogenic diet, allowing virtually no carbohydrates and 90 percent fat, to treat childhood epilepsy. Recently, a study conducted at the Johns Hopkins Children’s Center and published in the February 2010 issue of Epilepsia, confirmed that such diets are effective at treating infantile spasms and seizures that cannot be controlled with drugs. In fact, nearly 80 percent of the 101 patients in the study remained either seizure-free or had their seizures reduced by half. While this research showed the diet can temporarily raise cholesterol, impair growth and, in rare cases, lead to kidney stones, the evidence, especially among patients who were off the diet for more than 10 years, suggests no long-term harm.
Clearly a ketogenic diet is not one you should try on a whim, or begin without consulting your healthcare provider. In addition, there is still a good deal of research to be done on the approach. However, what is clear to date is that ketosis means fat-burning in the body and lower seizure risk for the brain.
Linda is a nutritional anthropologist and freelance writer in Portland, Ore. Her work has been featured in Body & Soul, Fitness, Glamour, Natural Health, Yoga Journal and many other national magazines. She is also the author of the User's Guide to Natural Remedies for Depression (Basic Health Publications, 2003).
July 19th, 2012