Your supermarket shelves are probably testament to the low-carb diet mania. You can buy low-carb pasta, bread, peanut butter and beer. Kim McDonald reports in "Duke Magazine" that in 2003, the low-carb food market was $30 billion; 24 million Americans were on low-carb diets that year. Low-carb diets are popular because they can help suppress your appetite; however, this diet approach comes with disadvantages, too. If you go low-carb, you may get too little of the important nutrients. You may eat more meat and fat --- which may increase your risk of cancer. And, ultimately, the long-term effects of low-carb diets are unknown, according to the Harvard Health Letter.
Major Criticisms
The major criticism of low-carbohydrate diets is that they mostly produce water loss with no real improvement of health. In additional, critics see them as unsustainable, possibly contributing to yo-yo dieting because many dieters regain the weight they lose on low-carb diets. Some popular low-carb diets require that you to abstain from fruits, some vegetables and whole grains. If you do that, you may miss out on some critical nutrients --- vitamins and minerals --- that carbohydrate-containing foods contain. The diet also flies in the face of the recommendations made by federal health officials in the Dietary Guidelines for Americans 2010, which recommend that most of your calories, 45 to 65 percent, come from carbohydrate sources.
Ketosis and Low Energy
A report by Vanderbilt University's Health Psychology Department states a common negative side effect of low-carb diets is ketosis, an "unhealthy metabolic mode" involving the buildup of waste products as your body breaks down fats. This happens when your body has burned out all of its carbohydrate stores and must turn to fat for energy. The buildup of ketones, however, can be a serious medical problem. It can result in the excretion of an abnormal amount of sodium and water. You may feel tired and lethargic as you experience ketosis, in addition to being extra gassy and constipated.
Not Better than Low-Fat Diet
In a review of studies on the subject, the "Harvard Health Letter" published a report suggesting that in the long-term, low-carbohydrate diets are no better than traditional low-calorie, low-fat diets. Initially, you may lose a lot of weight -- and far faster than those on other kinds of diets. In the studies reviewed, participants lost more in the first six months but went on to gain some weight back. After a year, low-fat dieters caught up with the weight loss achieved by low-carb dieters.
More Meat and Dairy
Individuals who follow low-carb diets may eat more meat and dairy than is advisable. This particularly increases their intake of saturated fats and dietary cholesterol. The "Harvard Health Letter" notes the extra saturated fat can elevate your bad cholesterol and raise your risk of heart disease. The extra protein may also have negative consequences. Kim McDonald in her "Duke Magazine" article (September-October 2004) states that too much protein can raise your risk of cancer. In addition, the protein load can adversely affect your kidneys, which gets taxed by being the only organ that breaks down the extra nitrogen from all the protein. Amanda Gardner reports in HealthDay News (September 2010) that getting more of your protein and fat from vegetable sources is a healthier option for low-carb adherents.
Impaired Cognition
When you eliminate carbohydrates from your diet, you may suffer reduced cognitive capacity, according to Tufts University researchers publishing in the February 2009 journal "Appetite." In an experiment with college-age women, carb avoiders performed more poorly on tasks that required use of memory, attention and concentration and learning. This occurs because glucose, which is most easily derived from dietary carbs, is your brain's most important fuel source. Results of the study suggest that if you abstain from carbohydrates for too long, your cognitive ability can diminish.
Long-Term Risks Not Identified
The University of Maryland Medical Center states that one of the chief problems with low-carbohydrate diets is that the medical community doesn't know their long-term health effects. The research on them is growing but is still in its infancy. More research is needed, as is the case with all dietary models, on how low-carb diets can affect adults, as well as special populations like pregnant women, children, the elderly and those who have kidney disease.
References
- Harvard Health Letter; Low Carb or Low Fat Diet?; July 2004
- University of Maryland Medical Center; Low-Carb Diets: The Right Way to Go?; April 20, 2007
- "Duke Magazine"; The Skinny on the Low-Carb Crazy; Kim McDonald; September-October 2004
- HealthDay News; Low-Carb Diets Heavy on Meat May Raise Health Risks; Amanda Gardner; September 6, 2010
- Virginia Cooperative Extension; The Low-Carbohydrate Craze: Is It a Healthy Way to Lose Weight?; May 1, 2009
- "Diabetes"; Low-Fat Versus Low-Carbohydrate Weight Reduction Diets; Una Bradley et al.; December 2009
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