Ketogenic Diets

4,271 views

Published on

A look at the role low-carbohydrate diets play in weight loss and the body.

0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
4,271
On SlideShare
0
From Embeds
0
Number of Embeds
87
Actions
Shares
0
Downloads
0
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide
  • supplies 4 kcal/gram
  • Ketogenic Diets

    1. 1. Ketogenic Diets<br />A look at the role low-carbohydrate diets play in weight loss and the body.<br />By:<br /> Will Barton<br />The information presented is NOT intended as medical advice and should <br />NOT replace the advise of a qualified physician.<br />
    2. 2. Carbohydrates 101<br />Carbohydrates 101<br />What is a Carbohydrate?<br />“A compound containing carbon, hydrogen, and oxygen atoms; most are know as sugars, starches, and fibers. ” 1,3 In human physiology the carbohydrate serves as the primary energy source. Traditionally breads, cereals, pasta, fruits, and starchy vegetables are promoted as ideal sources of carbohydrates.4 <br />Recommended Dietary Allowances(RDA): <br /> About 130 g/day 1<br />The Food and Nutrition Board recommends: <br /> To provide fuel for all of the bodies energy needs, carbohydrate intake should be considerably higher, ranging from 45 to 65% of all <br />energy intake (calories). 1,3 <br />There is no set carbohydrate consumptions for ketogenic diets. However, in the studies presented it ranged from ≤8% to 20% of energy intake.7,8,9,10,11,12,13,14,15<br />
    3. 3. Carbohydrates 101<br />Carbohydrates as Fuel <br />As carbohydrates are digested in the small intestine they are broken down to form glucose, which is a compound the body can utilize as a fuel source. Carbohydrates consumed in excess are stored in the liver and muscles as glycogen. During a period of fasting or low carbohydrate intake the body will convert the stored glycogen back to glucose in order to provide fuel to maintain normal body function.<br /> As the body’s glycogen stores begin to deplete, the body turns to its stored fats and body proteins. There it attempts to reserve the remaining and new glycogen for red blood cell function. Unlike other organs and cells of the body, red blood cells can only use glucose for fuel. <br /> When fats and protein are used as a fuel source they undergo a complex process to form glucose and/or ketones. However the bodies ability to form glucose form fat and protein is limited and not highly efficient. <br />
    4. 4. Carbohydrates 101<br />Ketones as Fuel <br />If carbohydrates remain unavailable or low (less than 50-100 g/day) the amount of glucose in the body drops, consequently causing insulin production to drop. Insulinamong many other functions decreases the breakdown of fat. This drop in insulin results in the release of large amounts of fatty acids from adipose (fat) tissue to provide energy for body cells.Sent to the liver to be broken down, the fatty acids are only partial oxidized (broken down) resulting in the formation of an acidic alternative fuel source called ketones or ketone bodies.As this partial oxidation persists, ketones accumulate in the blood causing a condition referred to as ketosis. 1,2,6<br />“Many low-carbohydrate/ high-fat weight-reduction diets (e.g.,TheAtkinsTM and South BeachTM) promote ketosis as a beneficial state for successful weight loss.” 1,6 Ketosis can suppress hunger, resulting in a lower caloric intake. The initial weight loss is NOT fat but water, as the kidneys attempt to rid the body of excess ketones. Ketogenic diets make the blood more acidic, upsetting the body’s chemical balance and causing potentially serious and unpleasant consequences, such as headaches, bad breath, dizziness, fatigue, nausea, dehydration, loss of lean body mass, and electrolyte imbalances. 1,2,6 “If severe, ketosis can cause coma and death.”1<br />
    5. 5. Carbohydrates 101 >> Ketones as Fuel <br />Ketosis<br />Ketosis does serve a purpose. If the body could not use ketones as an alternative fuel, the body would be forced to turn to protein. Resulting in the breakdown of muscles, heart, and other organs. 1,2 “The maintenance of body protein mass is crucial for survival in semi-starvation or fasting – death occurs when about half of the body protein is depleted, usually after about 50 to 70 days of total fasting.” 8 <br /> Those following a Ketogenic diet should be under a doctor’s supervision. “Clinicians who wish to use the ketogenic diet must be aware of the potential of serious adverse events (AE) and possible interactions of the diet with valproate (VPA).”6,7<br />
    6. 6. Weight Loss<br /> There are three main ways to reduce body weight:6<br /> (1) Dehydration<br /> (2) Lean weight loss (muscle)<br /> (3) Fat Loss<br />As a general rule of thumb if is healthy to loss about one pound per week. Reducing caloric intake by 500 kcal/day should result in a 0.45 to 0.9 kg (0.99 to 1.98 lbs.) of weight loss each week.<br />However ketogenic diets typically produce a 2 to 3 Kg (4.4 to 6.3 lbs.) weight loss in the first week. “This increased weight loss in NOT due to the miracle of switching the body’s metabolism over to burning fat stores. It is due to a diet-induced diuresis” (increased discharge of urine; AKA: water weight).1,2,5,6,9<br />
    7. 7. Weight loss >> Dehydration <br />1. Dehydration<br />Dehydration is NOT a recommend form of weight loss.<br /> It is not uncommon for athletes to utilize this method of quickly shedding a few pounds in order to “make weight” for a competition. Athletes the do participate in this method are encouraged to be in a good state of hydration to begin with and is maintained for only a few hours. “Do not rely on dehydration to lose more than a few pounds (usually less than 3 to 4% of total bodyweight)”6<br />Restricted Carbohydrates = Dehydration<br /> As carbohydrates are restricted, two metabolic processes occur, both of which simultaneously reduce total body water content. <br />
    8. 8. Weight loss >> Dehydration<br />Mobilization of Glycogen<br /> The mobilization of glycogen stores in liver and muscle is the first process. “Each gram of glycogen is mobilized with approximately 2 grams (g) of water. The liver stores approximately 100 g of glycogen and muscle has 400 g of glycogen. Mobilization of glycogen stores result in a weight loss of approximately 1 kg (2.2 lbs.)of primarily water wiegth.9<br />2. Formation of Ketone Bodies<br />The second process is the generation of ketone bodies from the catabolism of dietary and endogenous (stored) fat. Ketone bodies are filtered by the kidney as non-reabsorbable anions.10 Their presence in renal lumenalfluids increase distal sodium delivery to the lumen, and therefore increase renal sodium and water loss.<br /> In a study comparing an 800-calorie mixed diet with an 800-calorie low-carbohydrate, high fat diet,11 10-day weight loss was 4.6 kg (10.14 lbs.) on the ketogenic diet and 2.8 kg (6.17 lbs.) on the mixed diet. “Energy-nitrogen balanced studies documented that the difference in weight lost was all accounted for by losses in total body water.” The water shedding effect of the ketogenic diet is limited to about the first week.9<br />
    9. 9. Weight loss >> Lean Weight Loss<br />2. Lean Weight Loss<br /> “Lean Weight loss can result from an excessive reduction in caloric intake, losing weight too fast, not eating the proper proportions of macronutrients, and not exercising properly.”6 <br />“Lean Weight Loss comes primarily from the breakdown of muscle tissue; however, bone and connective tissue can also be reduced in size.”6,1,2,5,9<br />Margo A. Denke, MD shared in a study of ketogenic diets its potential to promote osteoporosis: “High-protein, low-carbohydratediets generate a high acid load, resulting in a subclinical chronic metabolic acidosis [ketoacidosis]. Metabolic acidosis promotes calcium mobilization from bone.12 Osteoclasts and osteoblasts respond to small changes in pH in cell culture; thus, a small decrease in pH results in a large burst of bone reabsorption.” 9,12<br />
    10. 10. Weight loss >> Lean Weight Loss<br />Decrease fat mass, spare lean body mass*<br />Volekand Westman studied this claim* using dual-energy x-ray absorptiometry to examine the change in body composition in subjects who switched from their habitual diet (48% carbohydrate, 32% fat) to a very-low-carbohydrate diet (8% carbohydrate, 61% fat) for 6 weeks.13 Surprisingly, fat mass decreased significantly (–3.3 kg) (-7.28 lbs.) and lean body mass increased significantly (+1.1 kg) (+2.23), despite no change in physical activity. There were no significant changes in the control group.14<br />*See note on following slide<br />
    11. 11. *Note: <br /> I did find it peculiar that the article Very-low-carbohydrate weight-loss diets revisited was the only article I was able to found that strongly defended Ketogenic diets as a way of “healthy weight loss.” (ketogenic diet have been found beneficial in the treatment of drug-resistant childhood epilepsy and other neurological disorders16) The authors of this article have indicated that they have received grant or research support from the Robert C. Atkins Foundation, Inc.14<br /> Robert C. Atkins founded “The Atkins Diet TM”, a ketogenic based diet. <br />
    12. 12. Weight loss >> Fat Loss<br />3. Fat Loss<br /> Losing weight through fat loss is the ideal and preferred manner to decrease ones body weight. A great way to achieve this goal is to increase your Lean Body Mass (LBM) or muscle mass. The greater LBM percentage one has the faster or more efficent the metabolism. <br /> The logic behind ketogenic diets is that by decreasing carbohydrate intake, insulin levels will drop. Once the insulin levels drop free fatty acids begin flooding the system. These fatty acids are than converted to ketone bodies to be used be the body for energy. <br />In theory this sounds great, but what about the potential side effects? <br />
    13. 13. Weight loss >> Fat Loss<br />Potential Side Effects<br />This is NOT a conclusive list of the potential side effect in question. <br /><ul><li>Micronutrient Deficiencies 9
    14. 14. Subclinical Metabolic Acidosis 9
    15. 15. Increased Blood Urea Nitrogen 9
    16. 16. Increased Uric acid levels 9
    17. 17. Urine Acidification 9
    18. 18. Hyperuricosuria9
    19. 19. Hypercalciuria9
    20. 20. Increased Urine Lithogenicity9
    21. 21. Impaired Higher Order Cognitive Function 9
    22. 22. Increased Free Fatty Acids 9
    23. 23. Increased LDLs 9
    24. 24. Progression of:
    25. 25. Coronary Artery Disease 9
    26. 26. Diabetic Nephropathy 9
    27. 27. Gouty Diathesis 9</li></ul> “There is insufficient evidence to make recommendations for or against the use of low-carbohydrate diets, particularly among participants older than age 50 years, for use longer than 90 days, or for diets of 20 g/d or less of carbohydrates. Among the published studies, participant weight loss while using low-carbohydrate diets was<br />principally associated with decreased caloric intake and increased diet duration but not with reduced carbohydrate content.”15<br />
    28. 28. Sources<br />Byrd-Bredbenner, Carol. Wardlaw's perspectives in nutrition. eight ed. McGraw-Hill Science Engineering, 2008. 153-187. Print. <br />Byrd-Bredbenner, Carol. Wardlaw's perspectives in nutrition. eight ed. McGraw-Hill Science Engineering, 2008. 294-295 . Print. <br />Food and Nutrition Board. Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington, DC: National Academy Press; 2002.<br />Byrd-Bredbenner, Carol. Wardlaw's perspectives in nutrition. eight ed. McGraw-Hill Science Engineering, 2008. pg.G-5 ”carbohydrate”. Print. <br />R., Thomas, Roger W. Essentials of strength training and conditioning. 3rd ed. Human Kinetics Publishers, 2008. 220-233. Print. <br />Hatfield, Frederick C. PHD,MSS. ISSA Fitness: The Complete Guide. 8th ed. ISSA, 2010. 519-535. Print. <br />"Complications of the Ketogenic Diet." 39.7 (2005): 744-48. Web. 8 Jul 2011. <http://onlinelibrary.wiley.com>.<br />VanItallie T, Nufert T. Ketones: Metabolism’s ugly duckling. Nutrition Review. 2003; 61:327.<br />Denke, Margo A., MD. "Metabolic Effects of High-Protein, Low-Carbohydrate Diets." American Journal of Cardiology. 88.July 1 (2001): 59-61. Print. <br />KolanowskiJ. On the mechanisms of fasting natriuresisand of carbohydrate-induced sodium retention. Diabetes Metab1977;3:131–143.<br />
    29. 29. Sources continued … <br />Yang MU, Van Itallie TB. Composition of weight lost during short-term weight reduction. Metabolic responses of obese subjects to starvation and low-calorie ketogenic and nonketogenicdiets. J Clin Invest 1976; 58:722–730.<br />Barzel. US, Massey LK. Excess dietary protein can adversely affect bone. J Nutr1998; 128:1051–1053<br />Volek JS, Sarman MJ, Love DM, et al. Body composition and hormonal responses to a carbohydrate-restricted diet. Metabolism 2002; 51:864-870<br />Volek, Jeff S.,PhD, RD, and Eric C.,MD, MHS Westman. "Very-low-carbohydrate weight-loss diets revisited." Cleveland Clinic Journal of Medicine. 69.11 (2002): 849-62. Print.<br />Bravata, Dena M., MD, MS, Lisa, MD Sanders, Jane, MD Huang, Harlan M.,MD,SM Krumholz, and Ingram, PhD Olkin. "Efficacy and Safety of Low-Carbohydrate Diets." American Medical Association. 289.14 (2003): 1837-50. Print. <br />Yellen, Gary. "Ketone bodies, glycolysis, and KATP channels in the mechanism of the ketogenic diet." International League Against Epilepsy. 49.8 (2008): 80-80. Print.<br />

    ×