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Unformatted text preview: Low Carbohydrate Diets
Jeff M. Housman, M.Ed. Review of Nutrition Principles Macronutrients supply energy in form of calories Carbohydrates Fat Yield 4 calories per gram Yield 9 calories per gram Yield 4 calories per gram Protein Review of Nutrition Principles All forms of macronutrients must first be converted to glucose (or simple sugar) to be utilized by the body. The body utilizes macronutrients in the following order: Carbohydrates Fats Proteins How Do LowCarbohydrate Diets Work? Intake of carbohydrates is restricted to a minimal amount. Without the presence of carbohydrates in the diet, the body goes into a state of Ketosis. Ketosis is defined as the presence in the blood of abnormally high levels of acidic substances called Ketones. How Do LowCarbohydrate Diets Work? During Ketosis, the body begins to convert fat and protein to glucose for fuel. Thus, individuals on a lowcarbohydrate diet lose fat. Science Behind LowCarbohydrate Diets Initial results from lowcarbohydrate diet studies indicate: Lowcarbohydrate dieters lose more weight in the shortterm than low fat dieters. Over 5 year periods, several studies indicate the difference in weight loss between lowcarb and lowfat dieters between 2 and 4 percent. Conclusion: In the longterm, weight loss difference is not significant. Dangers of LowCarbohydrate Diets When fats are used for fuel excessively, they are eventually converted to Ketones resulting in high acid levels in the blood. In some instances, high blood acidity is linked to an increase in risk for ulcers, stomach and throat problems, and cancer. Many researchers site concerns that weight loss is from dehydration. Dangers of LowCarbohydrate Diets Restriction on intake of fruits and vegetables. Fruits and vegetables have many vitamins and minerals, as well as fiber, needed for a healthy body. Vitamins and minerals are essential for most body functions including metabolism Fiber in fruits and vegetables helps lower cholesterol. Dangers of LowCarbohydrate Diets Lowcarbohydrate diets require and increase in water intake. Increase of consumption of proteins and fats may lead to cardiovascular problems. Increase in LDL or low density lipoprotein. Also known as the "bad" cholesterol. Higher fat consumption could lead to atherosclerosis or "clogging" of the arteries. Dangers of LowCarbohydrate Diets Specific to Women Ketosis requires an excess burning of proteins and fats for fuel. During Ketosis, muscle mass can be lost through conversion of muscle to protein. On average, women have slower metabolisms than men. Reduction of muscle mass will further slow metabolism. Dangers of LowCarbohydrate Diets Specific to Women Some studies have shown women lose bone mass during Ketosis. Results in an increased risk for osteoporosis. The loss of bone mass has been shown to be greater during menopause. Ketosis results in a high acidity level in the blood. In some instances, fertility difficulties in women have been linked to blood acidity. Current Popular Low Carbohydrate Diets There are many lowcarbohydrate diets on the market Atkins, South Beach, The Zone, Sugar Busters, etc. At the present time, the two most popular are Atkins and South Beach. The Atkins Diet Based on stringent restriction intake of carbohydrates Initial phase, 20 grams or less per day. Remain in the initial stage until you reach your ideal body weight. Stage 2 involves reintroducing some vegetables, but with a restriction on fruit. This stage is suppose to remain for a lifetime. Danger of The Atkins Diet Increase in consumption of saturated fats. May lead to increased cholesterol Increase in risk for atherosclerosis Decrease in energy Some have reported irregular heartbeats. The South Beach Diet Although this diet is included in the low carbohydrate diets, it is not as restrictive. Based on the Glycemic Index. Every food had a glycemic index (GI) and a glycemic load (GL). Foods with high GI create a large disturbance in your blood chemistry (i.e. blood sugar spikes, as does insulin). These foods digest quickly. The South Beach Diet Foods with a low GI create only a small disturbance in blood chemistry (i.e. blood sugar rises slightly, as does insulin). These foods digest slowly. When foods digest more slowly, you will be less hungry. Four things slow down digestion: protein, fat, fiber, and acidity. The South Beach Diet The diet has 3 stages. Stage 1: Eat lean proteins, unsaturated fats, and vegetables with a low GI. This stage lasts two weeks. Stage 2: Reintroduce whole grain carbohydrates and fruits with low GI. This stage lasts until you reach desired weight. Stage 3: Forget about the diet Dangers of the South Beach Diet Possible decreased energy. Possible increase in risk for heart problems. Summary Lowcarb diets work by reducing intake of carbohydrates and thus, fat and protein is burned for fuel. Body enters state of Ketosis which increases the acidity level of blood. May increase the risk for heart disease Hypertension Atherosclerosis Summary May reduce energy level. If you intend on starting a lowcarb diet, you should first visit your doctor and receive a full physical. References Bellamy, G. (2004). Calorie, Carb intakes upas waistlines buldge. Food Management, 5859. Foster, G., Wyatt, H., Hill, J., McGuckin, B., Brill, C., Mohammed, S., Szapary, P., rader, D., Edman, J., & Klein, S. (2003). A randomized trial of a low carbohydrate diet for obesity. New England Journal of Medicine, 348, 2082 2090. Glueck, C., Goldenberg, N., Wang, P., Loftspring, M., & Sherman, A. (2004). Metformin during pregnancy reduces insulin, insulin resistance, insulin secretion, weight, testosterone and development of gestational diabetes: prospective longitudinal assessment of women with polycystic ovary syndrome from preconception throughout pregnancy, Human Reproduction, 19(3), 510 521. Layman, D., Boileau, R., Erickson, D., Painter, J., Shiue, H., Sather, C., & Christou, D. (2002). A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women. American Society for Nutritional Services, 23, 234239 References Meckling, K., O'Sullivan, C., & Saari, D. (2003). Comparison of a lowfat diet to a low carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in freeliving, overweight and women. The Journal of Clinical Endocrinology & Metabolism, 89(6), 27172723. Samaha, F., Iqbal, N., Seshardi, P., Chicano, K., Daily, D., McGrory, J., Williams, T., Williams, M., Gracely, E., & Stern, L. (2003). A lowcarbohydrate as compared with a lowfat diet in severe obesity. New England Journal of Medicine, 348, 20742081. Volek, J., Sharman, J., Gomez, A., DiPasquale, C., Roti, M., Pumerantz, A., & Kraemer, W. (2003). Comparison of a very lowcarbohydrate and lowfat diet in fasting lipids, LDL subclasses, insulin resistance, and postprandial lipemic responses in overweight women. Journal of the American College of Nutrition, 23(2), 177184. References Volek, J., Sharman, M., Gomenz, A., Scheett, T., & Kraemer, W. (2003). An isoenergetic very low carbohydrate diet improves serum HDL cholesterol and triacyglycerol concerntrations, the total cholesterol to HDL ratio and postprandial lipemic responses compared with a low fat diet in normal weight, normolipidemic women. American Society for Nutritional Sciences, 24(1), 211 214. ...
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This note was uploaded on 03/26/2008 for the course HLTH 700 taught by Professor Chaney during the Fall '05 term at Texas A&M.
- Fall '05