Low Carbohydrate Diets
Carbohydrate is very important in humans’ diet because it has to perform several vital functions. It is used to maintain the blood sugar level, energy is released from them, dietary fiber is provided by them and hunger is satisfied by them. Carbohydrates are a very essential component of a balanced diet. Carbohydrates can be classified according to the rate of their absorption in blood. One type is very easily digested and enters blood stream thus resulting in quick rise in blood glucose level. Foods such as white rice, breakfast cereals and white bread are examples of this type of carbohydrate.
Another type of carbohydrates includes foods that are comprised of whole grains. It is very difficult to break them and thus the inclusion of glucose in blood stream becomes slow.
Overview of Low-Carbohydrate Diets
Low- carbohydrate diets are those diets that contain very limited amount of carbohydrate in them. There are different types of low-carbohydrate diets such as Atkins Diet that contains low carbohydrate and high fat contents; the South Beach Diet contains a balance between fat and carbohydrate; and the Zone Diet involves the consumption of proper ratios of fats, proteins and carbohydrates. Low-carbohydrate regimens such as the Atkins and South Beach diets have become increasingly popular–they don’t require exercise, allow unlimited caloric intake and are relatively effective.
The Zone Diet, as described by Barry Scars. PhD focuses upon a balanced diet with approximately 40 percent protein in the diet, 30 percent carbohydrates and 30 percent fats. Dr. Sears asserts that this ratio is ideal for keeping body hormones and chemistry in balance, but the evidence for this has not been published. However, I find Dr. Sears’ recommendations for the use of monounsaturated fats and exercise to be particularly attractive.
Arthur Agatslon, MD, author of The South Keach Diet, describes his diet as neither low-carb nor high-fat. Dr. Agatston describes certain foods as “dangerous” for inclusion in the diet. Examples of such foods include refined carbohydrates, saturated fats, hydrogenared oils and trans fatty acids.
The early phases of the South Beach Diet seem to be a modification of the recommendations made by Dr. Atkins. There are apparently three phases to the South Beach Diet, which also bear some similarities to the recommendations of Dr. Sears’ Zone Diet.
Some studies have shown that the diets do not elevate blood triglycerides or cholesterol levels in most people, in spite of relatively high fat intake However; they do increase blood cholesterol and triglycerides in some people.
Thus, the diets appear to be relatively safe in short-term, but little is known about long-term effects. These diets have side effects such as constipation from shortage of fiber and fatigue. They are deficient in certain minerals such as calcium and magnesium, low in antioxidants and often difficult to maintain because of sweets cravings.
History of Low-Carbohydrate Diets
Robert Atkins, MD, first introduced his low-carbohydrate diet in 1972 with his book Dr. Atkins’ Diet Revolution. Thirty years later, the book remains on best seller lists and has been joined by a second best seller. Atkins for Life. The Atkins diet has spawned not only countless other low-carbohydrate diets but also the creation of low-carbohydrate foods and an ongoing debate over the merits of low-fat versus low-carb diets.
Critics of low-carbohydrate diets say that the diets are unbalanced; that they restrict healthful foods that provide essential nutrients and that they are overly dependent on meat because low-carb diets are often high-protein diets. It is this last point that has led many to believe that a meatless, low-carbohydrate diet is an oxymoron.
Studies have shown the Atkins diet to be more effective in weight loss than traditional low-calorie diets and exercise plans–even without reducing caloric intake. Therefore, these diets appear to violate the principle that “calories in” must be less than “calories out” to lose weight. How can this be?
All carbohydrates are converted to blood sugar–better known as glucose–in the body. The Atkins and South Beach diets allow about 10 percent of the usual carbohydrate intake. This is not sufficient to supply the glucose needs of the body, since this important nutrient is the primary energy source for muscles and the brain. Glucose is also the starting material for synthesis of a number of important physiological and structural body components, and is the principle source of citric cycle intermediates. The citric cycle is the process where all nutrients are finally broken down to carbon dioxide and the starting materials for energy production. The cycle consists of eight compounds that must constantly be replenished because In addition to their role in energy production, these intermediates function as starting materials in various synthetic processes.
If carbohydrates are not adequate, the only source of glucose available to the body is protein since carbohydrate synthesis from fat is not possible. However, body protein is constantly broken clown and re-synthesized and dietary protein is required to supply the essential amino acids for the new proteins. These amino acids make up 10 of the 21 present in most dietary proteins, which leave only 11 of the total to be convened to glucose and to citric cycle intermediates. Thus, only about half of dietary protein is available for conversion to glucose.
Energy is required to convert amino acids from dietary proteins to glucose. First, nitrogen must be removed from the amino acid and converted to urea in order to be secreted in the urine. This process requires energy. The resulting deaminated acid products may then be convened to citric cycle intermediates and glucose, which also requires energy. Dietary fat and body fat must meet this energy requirement–and this is why the diet works. However, if citric cycle intermediates are depleted due to a shortage of glucose, the cycle cannot handle excessive fat breakdown and partially degraded fat remnants accumulate. These remnants are known as “ketone bodies.” Ketones can be used for energy, but excessive quantities may cause acidosis–which can be lethal although not at the quantifies generated in the Atkins and South Beach diets. Atkins, and to a lesser extent the South Beach diet, result in excessive ketone formation and excretion, which suggests that the citric cycle is not adequate to handle the load. Since ketosis is a symptom of citric cycle deficiency, it appears that dietary protein intake cannot sufficiently supply citric cycle intermediates and excessive fat catabolism simply overloads the cycle. Why doesn’t a diet high in saturated fats increase blood cholesterol and triglycerides in everyone? One answer is that fats must be used for energy needs in a low-carb diet and if excessive cholesterol is produced, this is also degraded for energy. The fact that low-carb diets are more effective than traditional low-calorie regimens and that exercise is not required suggests that the energy explanation of the efficacy of carbohydrate deficient diets is correct.
Restoring Insulin Sensitivity
The current low-carb fad has been caused by the misconception that eliminating carbohydrates rather than fat or protein results in weight loss in spite of a high caloric intake. However, this justification is only true under certain conditions. One reason might be that most Americans consume sugar-laden soft drinks and other carbohydrate snacks between meals. This results in elevated blood glucose levels, which don’t return to fasting levels until after a night’s sleep. Elevated blood glucose stimulates the secretion of insulin by the pancreas gland and insulin suppresses fat breakdown. Thus, there is never an opportunity for weight loss even with moderate exercise and a low-calorie diet. Insulin is required to facilitate entry of glucose into all cells. Furthermore, muscle cells have a limited capacity to store glucose and, when faced with an excessive supply, become forced to place a block on the glucose uptake system. The result is insensitivity to insulin–or type 2 diabetes. Once referred to as “late onset” diabetes seen only in the elderly, type 2 diabetes is now seen in children since young people are especially prone to consuming soft drinks and snacks throughout the day. This, and lack of exercise, are the reasons for overweight children. The Atkins and South Beach diets and the low-carb fad thus have a positive feature since they should restore insulin sensitivity by maintaining low blood glucose levels.
If blame is to be placed on one of the three dietary nutrients (carbohydrates, protein and fat) as the main cause of weight gain, it should be fat because it contains more than twice the calories per gram than carbohydrates or protein–9.3 calories per gram for fat and 3.7 calories per gram for carbohydrates. Furthermore, dietary fat can be converted to body fat without significant energy consumption, but the conversion of carbohydrate to fat is an energy-requiring process because carbohydrates must be partially broken down and then resynthesized into fat. Thus, considerably more carbohydrates than fat must be consumed to gain weight. Restricting fat is a much easier way to reduce caloric intake.
Safe, healthy and effective ways to avoid weight gain and its related health problems are to keep caloric intake down, exercise and avoid snacks in between meals. If it becomes impossible to restrict caloric intake, cut out snacks and soft drinks. This, combined with some exercise (e.g. a 30-minute walk most days of the week), should help most people maintain a healthy weight.
Low-Carbohydrate Diets Are Not Good For Health
Low-carbohydrates are not good for health. Following are the arguments presented against low-carbohydrate diets.
High-Protein Contents in Low-Carbohydrate Diets Give Rise to Health Issues
Low-carbohydrates are rich in proteins. The kidney and liver must have to work hard in order to metabolize high protein contents and for the elimination of by products that arise as a result of extra protein present in the diet. Diabetic renal disease may arise as a result of the hard work of the kidney and liver. Other parts such as heart, bone and joint of body may also be affected due to high protein contents present in a low-carbohydrate diet.
High Fat May Result Due to High Protein Contents
Usually a low carbohydrate diet consists of high protein contents. If that diet is composed of animal protein then it must be rich in cholesterol and saturated fats. This results in high LDL cholesterol levels in the body. Thus speed up the chances of heart diseases.
Other Risk Factors Due To Absence of Vegetables and Fruits
As a low carbohydrate diet is rich in protein, different organs of the body have to work hard to consume those high protein contents. This may result in an increased loss of calcium via urine. This increase in calcium loss may result in osteoporosis. Fruits and vegetables are rich sources of vitamins and minerals. When they are not included in a diet then a person may suffer from the deficiency of minerals and vitamins. Thus chances of cancers may increase.
Carbohydrates are very essential for the growth of the body. Carbohydrate is present in vegetables and fruits too which are rich sources of vitamins and minerals. These vitamins and minerals can protect a body from cancer. When intake of carbohydrate is insufficient, a body utilizes the glycogen which is stored in muscles. When the glycogen becomes less in muscles, a person may suffer from fatigue while exercising. Lean muscle tissues may be lost due to inadequate carbohydrate intake.
Not all the carbohydrates work in the same way. Carbohydrate sources such as white breads and foods that have been highly processed should be avoided. These food sources result in high blood glucose levels. Glycemic index is low in fruits and vegetables and in whole grains as it is very difficult to break them. As level of blood sugar does not raise quickly, insulin works slowly for the removal of the glucose, in this way, a body takes a longer time to have lower blood sugar levels and thus a person feels hunger after a longer time.
Agatston, A., MD. The South Beach Diet: The Delicious, Doctor-Designed, Foolproof Plan For Fast And Healthy Weight Loss. New York: Rodale, Inc. (2003).
Anderson JW, Konz EC, Jenkins DJA: Health advantages and disadvantages of weight reducing diets: A computer analysis and critical review. J Am Coll Nutr 2000; 19(5):578–90.
Atkins, R.C., MD. Dr. Atkins’ New Diet Revolution. New york: avon books, inc. (1990).
Bravata DM, Sanders L, Huang J, Krumhol HM, Olkin I, Gardner CD, et al. Efficacy and safety of low-carbohydrate diets: a systematic review. JAMA 2003; 289: 1837-50.
Brown L, Rosner B, Willett WW, et al.: Cholesterol-lowering effects of dietary fiber: A meta–analysis. Am J Clin Nutr 1999; 69(1):30–42.
Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA 2005; 293:43-53.
Holt S, Enhancing Low-Carb Diets, Wellness Publishing, Newark, New Jersey, 2004.
Ralof, J. “Counting Carbs.” Science News 166 (2004): 40-4.
Samaha, F. F., et al. “A Low-Carbohydrate As Compared With A Low Fat Diet In Severe Obesity.” The New England Journal Of Medicine 348 (2003): 2074-2081.
Westman, E.C., et al. “Effect Of 6-Month Adherence To A Very Low Carbohydrate Diet Program.” American Journal Of Medicine 113 (2002): 30-6.
 Atkins, R.C., MD. Dr. Atkins’ New Diet Revolution. New york: avon books, inc. (1990).
 Agatston, A., MD. The South Beach Diet: The Delicious, Doctor-Designed, Foolproof Plan For Fast And Healthy Weight Loss. New York: Rodale, Inc. (2003).
 Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA 2005; 293:43-53.
 Westman, E.C., et al. “Effect Of 6-Month Adherence To A Very Low Carbohydrate Diet Program.” American Journal Of Medicine 113 (2002): 30-6.
 Ralof, J. “Counting Carbs.” Science News 166 (2004): 40-4.
 Samaha, F. F., et al. “A Low-Carbohydrate As Compared With A Low Fat Diet In Severe Obesity.” The New England Journal Of Medicine 348 (2003): 2074-2081.
 Brown L, Rosner B, Willett WW, et al.: Cholesterol-lowering effects of dietary fiber: A meta–analysis. Am J Clin Nutr 1999; 69(1):30–42.
 Anderson JW, Konz EC, Jenkins DJA: Health advantages and disadvantages of weight reducing diets: A computer analysis and critical review. J Am Coll Nutr 2000; 19(5):578–90.
 Bravata DM, Sanders L, Huang J, Krumhol HM, Olkin I, Gardner CD, et al. Efficacy and safety of low-carbohydrate diets: a systematic review. JAMA 2003; 289: 1837-50.
 Holt S, Enhancing Low-Carb Diets, Wellness Publishing, Newark, New Jersey, 2004