FAQ About Low-Carb Diets

Low-carb diets are all the rage, but public health authorities aren't champing at the bit to recommend them. Why? Because there's no evidence to support them as a better strategy for weight loss than the standard advice of lowering your total calories and fat. So if you're embarking on a low-carb journey, you may be perusing the Internet and finding confusing, misleading and contradictory advice about how to go about it. Before you start, there are several questions to consider.

Are They Healthy?

Low-carb diets are a relatively recent entry on the public health research agenda. That means scientists don't know the long-term health effects of low-carb diets. The Dietary Guidelines for Americans 2010 says just about every American should get 45 to 65 percent of their calories from carbohydrate sources to be healthy. On a 2,000-calorie diet, that could be up to 325 g of carbs daily --- a far cry from the average of 50 carbs called for on many low-carb plans. According to an article in "Sports Science Exchange," health professionals have learned a few things. For example, low-carb diets can reduce your triglycerides --- fat in your blood --- and thereby lower your risk for heart disease. However, you might undo those benefits by consuming too few fruits, vegetables and fiber. Moreover, you may have reduced tolerance to physical activity on a low-carb diet. It's not known whether the benefits outweigh the risks. The University of Maryland Medical Center also notes that to be able to recommend low-carb eating, scientists need to know how it affects different populations, such as pregnant and nursing women, the elderly, children and especially those who have kidney problems and need to limit protein. The science just isn't there yet.

Do They Work?

This question unfortunately gets a "yes, but" response. An article in "Harvard Health Letter" reported that in research comparing low-carb to low-fat diets, low-carbers lost dramatically more weight in the first six months. Later research reported in the "Annals of Internal Medicine" said low-carbohydrate diets without calorie restrictions are effective at inducing weight loss for up to a year. But, after that, the differences between low-fat/low-calorie diets and low-carb diets start to disappear. This happens for a couple reasons. Much of the early weight loss in low-carb diets is attributed to water weight. The diets cause ketosis, which causes you to excrete a large amount of fluid and sodium. The kidneys can adjust to this over time. In addition, adherence to low-carb eating is difficult. Harvard's School of Public Health finds that after maintaining their discipline for some time, participants in low-carb studies drop out or admit they cheated on the diet. Their weight at the end of the study has not been statistically different from others following different diet plans. In the long term, defined as a year, low-carb diets are about the same as low-fat diets.

What Are the Side Effects?

Carbohydrates supply energy to your cells and fuel your brain. When you consume too few carbohydrates, you may suffer cognitively. That's what Tufts University researchers reported in the journal "Appetite." After studying a group of female college students, the researchers found that the women performed worse on tasks that required use of memory, including long- and short-term, as well as spatial memory. In addition, the ketosis you experience on low-carb diets may leave you feeling tired and lethargic. Ketosis is an unhealthy buildup of waste products created when your body turns to fat for energy.

How Long Can I Be on a Low-Carb Diet?

Most research of low-carb diets has followed participants only from six months to a year. Although some proponents of low-carbing adopt it as a lifestyle choice, your ability to sustain that kind of eating will be challenging. In addition, the research reported in the "Annals of Internal Medicine" said low-carb participants experienced significant increases in their bad cholesterol in just the one year of study. If you plan to try low-carb dieting, ask your health care provider to guide you through a timeline appropriate for you and ensure you monitor your blood lipids to stay healthy.