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WLG 126 L ow-carb Diets: Could They Possibly Be That Good? Guen Brown, Extension Specialist, Nutrition and Health Jason Nguyen, M.S./R.D. candidate, West Virginia University Low-carbohydrate diets, like the Atkins Diet, have been around for a long time. Do they work? Are they safe? The list below shows some of the more well-known low-calorie diets. The different types do have minor variations, but all are basically low-carb diets. • Atkins Diet, probably the most famous one, by Dr. Robert Atkins • High-protein Diet • Stillman Diet • Scarsdale Diet • Hollywood Diet • Ketogenic Diet • Zone Diet • South Beach Diet What Are Low-carb Diets? Low-carb diets are based on the premise that a diet very low in carbohydrate leads to a reduction in the body’s insulin production, resulting in fat and protein (muscle) stores being used as the main energy source. However, the recommended carbohydrate intake varies among diets. Some low-carb diets restrict carbohydrate intake to less than 20 percent of total calories; others permit up to 40 percent. To complicate matters further, many low-carb diets are divided into “phases.” Phase 1 typically permits only minimum amounts of carbs; Phases 2 and 3 are usually more generous. Compare this with the U.S. Department of Agriculture (USDA) recommendation to eat about 50 percent to 55 percent of calories from carbohydrates. The fat intake recommendations vary too. Some low-carb diets suggest eating 55 percent to 65 percent of one’s calories from fat. USDA recommends eating not more than 30 percent of calories from fat. What is even more controversial, is that some low-carb diets actually state that animal fats may be eaten liberally along with vegetable oils. This advice contradicts the recommendations of most heart specialists. The aim of low-carbohydrate diets is to force the body to use fat as its main energy source, since no carbohydrates are available. When fat is being used to provide fuel for your body, the liver produces ketone bodies to provide energy for parts of the body that cannot use fat as an energy source, particularly the brain and red blood cells. If ketone bodies are made faster than they are used, they build up in the blood and cause a condition known as ketosis. Ketosis can cause your body’s organs to fail and result in gout, kidney stones, kidney failure, nausea, loss of appetite, and bad breath. If this keeps up, your body’s blood becomes too acidic. This is called ketoacidosis and can lead to brain damage and eventually death. Suggested protein intake in low-carb diets ranges from 25 percent to 40 percent. The USDA recommends you get between 15 percent and 20 percent of calories from protein. Since fat and protein are generally found in the same foods, a diet high in fat is usually high in protein. – continued – These foods are restricted in a low-carb diet. What Are Carbohydrates? Carbohydrates or “carbs” are the main source of energy for the body. Grains, fruits, legumes (beans, peas, and lentils), dairy products, and vegetables contain carbohydrates. The two main types of carbs in food are simple carbohydrates (sugars) and complex carbohydrates (starches and higher-fiber foods). These foods are often restricted in a low-carb diet. Simple carbohydrates are found in soda pop, candy, pastries, and other sweets. They provide energy that is 5 grams. The amount of carbohydrates needed depends quickly used by the body before it uses protein and fat, upon a person’s total calorie needs. However, eating a diet the other energy sources from food. Unfortunately, foods containing generous amounts of fruits, vegetables, grains, with high amounts of simple carbohydrates do not usually and cereals is an excellent practice for both adults and contain any important vitamins or minerals. This means children. The Food and Nutrition Board of the National that they provide empty calories. Academy of Sciences has reported that the absolute Complex carbohydrates are chains of sugars. Legumes, minimum amount of carbohydrates the body needs per potatoes, yams, and grains such as wheat, rice, corn, day is 50 to 100 grams (Dietary Reference Intake Table, and oats are complex carbohydrates in the form of starch. USDA Food and Nutrition Board, June 2004). While all plant foods contain fiber, our body does not digest fiber, and no calories are produced. Starches take longer to be digested than simple sugars. Eating starchcontaining foods makes our body feel full, and energy is provided more slowly. Your body converts or breaks down most carbohydrates into glucose. Glucose is circulated through the body in blood and provides energy. The primary fuel used by the brain is glucose. Some glucose can also be stored in the muscles and used for exercise, helping your body function properly without tiring easily. How Much Carbohydrate Should I Eat? A normal starch, fruit, or sweet food serving contains about 15 grams of carbs. One serving of dairy food has about 12 grams, and a vegetable serving consists of only Do Low-carbohydrate Diets Work? In the short term, most people who go on low-carb diets do lose weight, and they lose it very quickly. However, the majority of weight loss comes from loss of water and muscle tissue, not fat, which is what you need to lose to keep the weight off. Also, if you’re trying to lose weight permanently, losing precious lean muscle tissue is like sabotaging your own body. Muscle tissue burns calories even when you are at rest. A decrease in the amount of muscle tissue you have will lead to a decrease in the number of calories you need each day to maintain your weight, making it much harder to keep your weight under control when you stop following the low-carb diet. High-protein, low-carbohydrate diets seem to work, at least in the beginning. Dieters experience an initial weight loss, but it is rarely permanent. The weight reduction is a result of lost water and body fluids. Energy (glucose) stores are depleted, which can lead to fatigue, weakness, nausea, constipation, and dehydration. Later, the decrease in weight comes from loss of fat and muscle tissue. This may affect vital body organs. Weight is usually regained quickly if the diet is stopped. What’s Involved? Eating a well-balanced meal is better. Basically you cut out virtually all carbohydrate from your diet and increase your protein and fat intake. So you cut out things like pasta, bread, rice, and alcohol, but you eat unlimited amounts of meat, cheese, and butter. That’s why the Atkins Diet claims are so appealing. Are There Other Things I Need to Know About Low-carb Dieting? The low-carb diet craze has led to an explosion of new food products and advertisements in grocery stores and restaurants. While many food items are essentially new, the concept of low-carb foods is not “revolutionary.” Neither is it a breakthrough in weight management. Rather, the idea originated in the 1950s and has been in and out of style every few years for the past five decades. More recently, the Atkins Nutritional Approach, South Beach Diet, Zone Diet, and several other high-protein, low-carb diets have gained popularity. They are similar in that they encourage eating lean meats, eggs, cheeses, nuts, and oils while restricting grains (bread, rice, cereal, pasta), fruits, some dairy foods, and vegetables. Because people tend not to stay on the diets for long periods, little research has been done on the long-term health effects of following this eating pattern. However, when grains, some dairy products, and fruits and vegetables are restricted in the diet, many essential nutrients are not available in recommended amounts. Also, no legal definitions exist for “low carb.” An official way of figuring them out has not yet been established by the Food and Drug Administration (FDA). To cater to high-protein, low-carb dieters, food products are being introduced with “low net carbs” by substituting sugar alcohols for sugar or by increasing the fiber content. Eating excessive amounts of sugar alcohols can have a laxative effect. A high-fiber diet has been linked with a lower risk of heart disease, diabetes, and possibly colon cancer. However, a sudden increase in fiber intake can cause increased intestinal gas and bloating. Increasing fiber intake should be done gradually over several weeks, accompanied by drinking lots of fluids to prevent digestion complications. The animal foods and products in these fad diets can be high in cholesterol and saturated fat, which leads to heart problems. Avoiding healthy foods and food groups altogether will lead to malnutrition, diseases, and some cancers. Ignoring or strictly limiting fruits and vegetables is not recommended. These foods contain cancer-fighting vitamins, or antioxidants, and have other health benefits. Is a Low-carb Diet Healthy? In a word, no! Essential vitamins and nutrients come from a balanced diet, and low-carbohydrate diets certainly are not balanced. You can get many essential nutrients from fruit, vegetables, and grains. Low-carb diets allow only very small amounts of fruit and vegetables – definitely not enough to provide your recommended daily allowance. The Atkins Diet claims to clear up all manner of ailments, but the bottom line is that these diets are lacking in nutrients essential for good health. Also, the high level of protein puts a huge strain on your kidneys. Low-carb diets are also likely to encourage yo-yo dieting – cycles of losing and regaining weight – which has been shown to be a health risk. So Why Do It? People are often attracted to low-carb diets because weight loss is very rapid, and we like to see instant results on the scales! Many times, people in the entertainment world go on low-carb diets because they want to lose weight quickly. They don’t do it for permanent weight loss or good health. Others may not understand the possible long-term effects of diets that are not based on a variety of foods. Is There a Take-home Message? Diets that recommend cutting back on carbohydrate foods are an “in vogue” means of losing weight. They have gained a lot of media attention. However, these diets could actually harm health in the longer term. The American Heart Association has expressed concern that their high-fat content, particularly saturated fat, increases the risk of heart disease in those who follow these diets long term. Low-carbohydrate diets go against all the current recommended healthy eating principles and are deficient in many vitamins, minerals, and dietary fiber since they restrict the intake of fruit and vegetables. There are also concerns that these diets, if followed long term, may increase the risk of kidney, bone, and liver problems. Combining a balanced, healthy diet with exercise is still the most effective and safe long-term way to lose weight. However, the results are gradual and require perseverance. Quick fixes such as low-carb diets do not hold up to scrutiny. There are no long-term studies on the safety or efficacy of these diets. Perhaps the greatest risk of the low-carb diet trend is the impact it may have on eating behaviors of individuals who haven’t established sensible eating habits. Weight management incorporates a balanced lifestyle of a healthy diet and regular physical activity. In order to lose weight, you must eat fewer calories than you use. Decreasing portion sizes and keeping a diary of the foods you eat can lead to long-term health. Low-carbohydrate diets are not recognized as healthy diets. Making small changes, such as decreasing portion sizes and increasing physical activity, are healthy ways to lose weight. References USDA Food and Nutrition Board, June 2004 Institute of Medicine of the National Academies, August 2004 American Heart Association Statistical Fact Sheet, Nutrition and Heart Disease, May 2004 2005: 1M Programs and activities offered by the West Virginia University Extension Service are available to all persons without regard to race, color, sex, disability, religion, age, veteran status, political beliefs, sexual orientation, national origin, and marital or family status. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Director, Cooperative Extension Service, ES05-1 West Virginia University.