The Skinny on Low-Carbohydrate Dieting
Carbohydrates are a major component of a person’s diet, used by the body for energy. The body converts carbohydrates for energy, efficiently breaking them down into glucose, or blood sugar. Once in the blood, this glucose is mobilized by insulin and distributed throughout the body as fuel. Carbohydrates form a major source of energy for all areas of the body and are a particularly important source of energy for the central nervous system.
Low-carbohydrate diets, as the name implies, involve eating a lower portion of carbohydrates than is typically recommended by most food guidelines. For example, the 2010 Dietary Guidelines for Americans suggest that the average person should aim to consume between 45 to 65 percent of their daily calories from carbohydrate sources. For a 2,000 calorie diet, this translates to somewhere between 225 and 325 grams per day.
Popular versions of low-carbohydrate diets include the Atkins diet, the Zone and Zone Perfect diets, but there are many other variations out there in the popular media. Each plan has variations around how low a person’s daily carbohydrate intake should be, ranging from as little as 50 grams to 150 grams of carbohydrates per day.
Carbohydrates are also known as starches, sugars, simple and complex carbohydrates. They are found in a number of common food sources, such as breads, grains and cereals. Other common dietary sources of carbohydrates include milk, fruits and vegetables, seeds, nuts and legumes. On top of the naturally occurring carbohydrates in foods, manufacturers often add wheat flour or starches during the processing of foods, increasing their carbohydrate content.
Complex carbohydrates are those that take a bit longer for the body to break down and provide a variety of minerals, vitamins and fiber. Good examples of complex carbohydrates include whole-wheat pastas, legumes and starchy vegetables like potatoes. Whereas simple carbohydrate is a term used to describe carbohydrates that break down more quickly into sugars, such as milk (lactose), fruits, vegetables and confectionery items such as cakes and candies.
Following a low-carbohydrate might result in a higher rate of weight loss than other lower fat or lower calorie diets, at least in the short term reports the “New England Journal of Medicine” in May 2003. However, this study also found that while a low-carbohydrate diet surpassed other diets in the short-term, at the year mark, there was no difference in how quickly one lost weight on this diet over the other low-fat or low-calorie diets.
Low-carbohydrate diets work by promoting a condition known as ketosis, where the body has depleted glycogen levels available for fuel and turns to fat stores for fuel. It is thought that this state of ketosis contributes to the increased weight loss. A low-carbohydrate or ketogenic diet might promote lower cholesterol levels, reports MayoClinic.com; however, further research is required to support and confirm this effect.
The most common side effect of ketosis is fatigue, decreased concentration and nausea. This occurs because a low-carbohydrate diet does not provide enough nutrients and fiber. Ketosis also contributes to bad breath in some people, while others will be plagued with constipation or diarrhea, muscle spasms, dehydration and headaches. Following a low-carbohydrate story can also lead to more serious side effects like the development of gallstones, nutrient deficiencies and osteoporosis. In some cases, females following a low-carbohydrate diet may experience delays in or cessation of menstruation.
Restricting carbohydrate consumption to extreme levels can lead to insufficient fiber consumption and nutritional deficiencies, for which the side effects are many. As of 2012, most studies have not followed subjects for more than a year on low-carbohydrate diets. The long-term effects of a low-carbohydrate diet on the body remain unknown.
Research supports the use of low-carbohydrates in the short-term. However, as with any diet, unless a person follows maintenance nutrition and fitness plans, the positive results are likely to be short lived. As the long-term effects of following a low-carbohydrate diet are unknown, a prudent approach to low-carbohydrate dieting should be applied. If a low-carbohydrate diet is being considered, discuss this first with a physician and registered dietician to ensure that there are no medical reasons to avoid this diet plan, and to determine whether this eating plan meets your specific nutritional needs.
Dietary Guidelines for Americans
“Epilepsia”: The Ketogenic Diet: Adolescents Can Do It, Too
MayoClinic.com: Low-Carb Diet
“The New England Journal of Medicine”: A Randomized Trial of a Low-Carbohydrate Diet for Obesity