Carbohydrates and Dieting
Consumers are inundated with propaganda from the purveyors of quick-fix diet fads. Books, infomercials and talk shows publicize unusual approaches to dieting by promising rapid weight loss. One such approach, the no or low carbohydrate-diet, has left many consumers confused over the purpose of carbohydrates in their diet and the role carbohydrates play in proper nutrition. For those wishing to lead a sustainable healthy lifestyle, the record on carbohydrates must be set straight.
The human body requires and prefers carbohydrates as its main source of energy. Carbohydrates provide the fuel for muscle and central nervous system activity and help the body efficiently use vitamins, minerals, amino acids and other essential nutrients.
Carbohydrates are broken down in the body in the form of a simple sugar called glucose. Glucose is either circulated in the blood to provide cells with immediate energy or it is processed into glycogen, which is stored for later use by the body when activity demands more energy. When energy is needed, the available glycogen is converted back into glucose and released into the bloodstream to satisfy the body's demand for power and stamina.
Bananas, like other fruits and vegetables, contain complex carbohydrates, which are very important to any diet. In contrast to simple sugar foods like soda and sweets, bananas offer the body good nutrition as well as available energy. Bananas are a good source of vitamin C, potassium and dietary fiber, and bananas also contain a rich supply of vitamin B6.
Advocates of no or low-carbohydrate diets argue that the intake of carbohydrates should be minimized in diets to force the body to undergo a process called ketosis. Ketosis occurs during a fasting state and burns the body's fat to produce a byproduct called ketones. Ketosis leads to an abnormal increase of ketone chemicals in the body in conditions of reduced or disturbed carbohydrate metabolism1. The ketone compounds are then used as energy to make up for the lack of glucose in the body. While combusting the body's stored fat, ketosis can cause symptoms such as fatigue, weakness, mild nausea and dehydration. The potential long-term side effects of ketosis include heart disease, bone loss, and kidney damage2.
By following a low-carbohydrate diet, eating patterns require virtually the elimination of most, if not all, fruits and vegetables. Because studies show that the consumption of fruits and vegetables decreases the risk of developing cancer and heart disease, the restriction of fruits and vegetables in a diet would actually be a detriment to long-term health.
Experts agree that a balanced diet is the key to a healthy lifestyle, and that carbohydrates are a necessary part of that balance. The elimination of entire food groups under the low-carbohydrate plan contradicts the balanced approach to nutrition. The U.S. government recommends that the human diet should consist of 6 to 11 servings of carbohydrates each day, or about 55% of daily calories should come from carbohydrates. Diets should be mostly plant-based and rich in whole grains, low-fat dairy products and plenty of fruits and vegetables. Please refer to the publication Nutrition and Your Health: Dietary Guidelines for Americans and related information from the U.S. Departments of Health and Human Services and Agriculture.
U.S. government officials have cited preliminary results from a USDA study of about 5,000 Americans who stuck to the food guide pyramid. About 20 percent to 30 percent of their calories came from fat, about 55 percent from carbohydrates and 15 percent from protein. Both men and women who followed the government's advice had a lower body mass index, a measurement of a person's weight in relation to their height, than people on a low-carbohydrate diet3.
The USDA study further concludes, "High-fat, low-carbohydrate diets are nutritionally inadequate. They are low in vitamins E, A, thiamin, B6, folate, calcium, magnesium, iron, zinc, potassium, and dietary fiber, and require supplementation." To view the USDA's executive summary of this research, please go to http://www.usda.gov/news/releases/2001/01/whitepaperexe.htm.
For additional information on the impact of fad diets, please see the article by the American Dietetic Association titled "Fad Diets: What You May Be Missing" at http://www.eatright.org/nfs/nfs0200b.html.
1 Webster's Medical Dictionary, 1995
2 American Dietetic Association
3 American Dietetic Association's Annual Meeting, 2000
