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Low Carbohydrate Diets for Athletes Jeff S. Volek, PhD, RD

The Problem: A key element contributing to deteriorating cognitive and physical performance during exercise is reduced carbohydrate availability coupled with an inability to effectively utilize alternative lipid fuel sources. Paradoxically, deteriorating performance associated with glycogen depletion occurs in the presence of an abundance of fuel stored as body fat that the athlete cannot access efficiently. For example, a very lean athlete has access to >40,000 kcal from body fat, even at the point of fatigue. Current fueling tactics emphasize carbohydrate-based diets and sugar-based supplements that bias metabolism toward carbohydrate while simultaneously inhibiting fat utilization. The high carbohydrate paradigm can provide short-term benefit, but has inherent drawbacks for athletes and produces unreliable results, especially during prolonged exercise when body carbohydrate stores are limited. Deteriorating cognitive and physical performance in the context of low carbohydrate availability could be circumvented if the athlete could access lipid fuel. However, unless the athlete has previously undergone ‘keto-adaptation’ they will be unable to effectively transition to using predominantly lipid fuel. An Innovative Solution: A strategy that allows improved availability and utilization of lipid fuel is needed. Regular physical training or dietary supplements (e.g., caffeine, ephedrine) offer a modest benefit in fat burning. However, the most efficient approach to accelerate the body’s ability to access and burn fat is to restrict dietary carbohydrate while increasing fat intake for a period of several weeks, after which fatty acids and ketones become the primary fuel at rest and during submaximal exercise. The coordinated set of metabolic adaptations that ensure proper inter-organ fuel supply in the face of low carbohydrate availability is referred to as keto-adaptation. Rather than starting a workout or event depending primarily on <2000 kcal of glycogen, a keto-adapted athlete has ready access to a fuel source that is at least 10 to 20-fold greater. Benefits Associated with Keto-Adaptation: Better fuel delivery to brain Decreased reactive oxygen species (ROS) Improved insulin sensitivity Protein sparing Decreased central fatigue Less lactate Decreased ventilatory drive Improved body composition/power-to-weight ratio) Better/faster recovery Reduced systemic inflammation and inflammatory response to intense exercise

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Less disruption to muscle membranes and indicators of muscle damage Better preservation of critical cell membrane components involved in gut cyto-protection

(i.e., less mucosal damage and exercise-induced GI bleeding) Improved host defense against infection

Important Principles: A primary application of very low carbohydrate ketogenic diets in adults is in the

management of insulin resistant conditions. Insulin resistance is the hallmark of type-2 diabetes and is also the primary defect underlying metabolic syndrome. Metabolic syndrome often presents as dyslipidemia (high serum triglycerides, low HDL-C, and a predominance of small LDL particles), hyperglycemia, hyperinsulinemia, hypertension, vascular dysfunction, and increased inflammation and adiposity. In respect to carbohydrate metabolism, insulin resistance is associated with impairments in hepatic glucose output and skeletal muscle glucose uptake, as well as a greater propensity to convert glucose to fat (de novo lipogenesis). Thus, insulin resistance is characterized by impaired metabolism of carbohydrate or in other words it is a ‘carbohydrate intolerant’ state that is most effectively managed by restricting dietary carbohydrate to a level that can be tolerated.

Athletes also vary in their ability to metabolize carbohydrate. Those who manage carbs well have more diet options. Those who don’t have fewer options and respond best to restricting carbohydrate.

Nutritional ketosis is very different than keto-acidosis. Ketones serve as a vital fuel source for the brain and muscles, and recent evidence indicates there are modulators of gene expression upregulating key pathways involved in protection from excessive oxidative stress.

Fundamentals of a Well-Formulated Low Carbohydrate Diet: The magnitude of carbohydrate intolerance varies considerably among people and therefore

the level of restriction required to optimize fat loss and achieve metabolic control varies from person to person. Consumption of less than 50 grams carbohydrate per day is necessary in most people to elevate ketones above 0.5 mmol/L, the threshold for nutritional ketosis. When carbohydrates are restricted to less than 50 grams per day, over a period of about 2-3 weeks a process called keto-adaption occurs where the body efficient at breaking down and burning prodigious amounts of fat. And if calories are restricted, much of that fuel comes from stored body fat.

Protein is important but it should be consumed in moderation (no more than 2 grams per kilogram body mass). Consuming excessive amounts of protein can interfere with keto-adaptation, and it poses an unnecessary stress on nitrogen removal from the body.

Fat calories should be emphasized to provide fuel, flavor, and satiety. The types of fat to

emphasize are the ones the body prefers to oxidize, which are saturated and monounsaturated fatty acids (SFA and MUFA, respectively).

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Salt is a critically important micronutrient, especially on a low carbohydrate diet. When carbohydrates are restricted the body starts to discard water and salt. It’s not uncommon for people to lose 4-5 pounds of water weight during the first week of a low carbohydrate diet. If that salt is not replaced the body responds by trying to retain more salt. This primarily happens in the kidneys. As a result, the kidneys start to waste potassium leading to a negative potassium balance. The loss of water and salt can reduce plasma volume resulting in many of the common side effects often attributed to ketogenic diets (e.g., fatigue, fainting, headache, inability to exercise). Consuming an extra 1-2 grams of sodium per day alleviates these effects in most cases.

Much Ado About Carbs

By Alan Aragon Site: www.alanaragon.com

Blog: www.alanaragonblog.comContact: alaneats@gmail.com

First off, a word of…

Agenda

Position & DefinitionsExperimental evidence Observational evidence Client Case StudiesDiscussion

Assume the Position1

Definition of Low‐CarbProportional:2   

LCD……………20‐40% CarbLCHP………….20‐40% Carb, 30‐60% Prot, 20‐30% FatNKLCHFD…..20‐40% Carb, 20‐30% Prot, 30‐60% FatVLCD………….0‐20% CarbVLCHPD …….0‐20% Carb, 55‐65% Prot, 25‐35% Fat

Absolute:3

LCD (general)…50‐150 g Carb (10‐30% given 2000 kcal). 200 g has also been suggested as the upper threshold, but there is disagreement that this qualifies as a LCD.

LCKD/VLCKD…<20‐50 g Carb (4‐10% given 2000 kcal).

Experimental Evidence2009:  Hession et al conducted a meta‐analysis of randomized 

controlled trials (RCTs) of low‐carbohydrate /high‐protein diets versus low‐fat/high‐carbohydrate diets, lasting a minimum of 6 months [4]. 13 studies (n = 1222) examined, main findings were:• Weight loss was significantly greater in the LC/HP group after 6 

and 12 months compared with the LF/HC group.• There was a significant  improvement in HDL cholesterol and 

triacylglycerols at 6 and 12 months favoring the LC/HP group, but this was not significant at 17 months.

• There was a trend towards improvement in blood pressure at 6, 12 and 17 months favoring the LC/HP group.

• At 6 months there was a trend towards improvement in fasting plasma glucose only slightly favoring the LF/HC group.

• There was a higher attrition  (dropout) rate in the LF/HC compared with the LC/HP groups.

Experimental Evidence2006:  Johnston et al compared weight loss and biomarker change 

in adults  on a ketogenic low‐carbohydrate (KLC) diet or a nonketogenic low‐carbohydrate (NKLC) diet for 6 weeks [5]. The main findings were:

• Weight loss was 6.3 kg in KLC and 7.2 kg in NKLC and NLC dieters, respectively (P = 0.324).

• Fat loss was 3.4 kg in KLC and and 5.5 kg in NKLC dieters, respectively (P = 0.324). 

• Overall, insulin sensitivity and resting energy expenditure increased and serum gamma‐glutamyltransferase concentrations decreased in both diet groups (P < 0.05).

• Inflammatory risk (arachidonic acid:eicosapentaenoic acid ratios in plasma phospholipids) and mood/perceptions of vigor were more adversely affected by the KLC than by the NLC diet.

Experimental Evidence2012:  Hu et al compared the effects of low‐carbohydrate diets (4–45% 

of energy from CHO) versus low‐fat diets (≤30% of energy from fat) on metabolic risk factors in a meta‐analysis of RCTs [6]. 23 trials (n = 2788) examined, main findings were:

• Compared with LF diets, persons on LC diets experienced a slightly but statistically significantly lower reduction in total cholesterol.

• LC diets caused a lower  reduction in LDL‐c but a greater increase in HDL‐c and a greater decrease in triglycerides.

• Reductions in body weight, waist circumference and other metabolic risk factors were not significantly different between the 2 diets. 

• This is evidence that are extremely versatile when it comes to diet. We can achieve excellent health on a very wide range of macronutrient compositions. The universal supremacy of a single type of diet (e.g., low‐carb or low‐fat) simply lacks evidence.

Experimental Evidence2005:  Cornier et al investigated whether insulin sensitivity  in non‐

diabetic subjects affects the response to a HC/LF diet (60% CHO, 20% fat) versus a LC/HF diet (40% CHO, 40% fat) under hypocaloricconditions [7]. The main findings were:

• Insulin‐sensitive women on the HC/LF diet lost 13.5% of their initial BW, whereas those on the LC/HF diet lost 6.8%.

• In contrast, among the insulin‐resistant women, those on the LC/HF diet lost 13.4% of their initial BW while those on the HC/LF diet  lost 8.5%.

• Insulin sensitivity determined the effectiveness of macronutrient composition of hypocaloric diets in obese women, and interestingly,  the greatest weight loss among the conditions was experienced by insulin‐sensitive subjects put on the HC/LF diet. 

Research‐Based Recommendations  for Athletes2010 ISSN Research Update [8]: 

• Individuals engaged in a general fitness program can typically meet needs by consuming a normal diet (45‐55% CHO; 3‐5 g/kg/day).

• Athletes involved in moderate amounts of intense training (2‐3 hrs/day, 5‐6 times/week) typically need to consume 55‐65% CHO (5‐8 g/kg/day or 250 ‐ 1,200 g/day for 50 ‐ 150 kg athletes) in order to maintain liver and muscle glycogen stores.

• Athletes involved in high volume intense training (3‐6 hrs/day of in 1‐2 workouts for 5‐6 days per week) may need to consume 8‐10 g/kg/day of carbohydrate (i.e., 400 ‐ 1,500 grams/day for 50 ‐ 150 kg athletes) in order to maintain muscle glycogen levels.

2009 Position of the ADA, Dietitians of Canada, and the ACSM [9]:• Carbohydrate need of athletes are 6 ‐10 g/kg/day, depending on total 

daily energy expenditure, type of sport, sex, and environmental conditions.

Observational Evidence (General Population): Dietary Habits of the World’s Longevity Champs

Dietary Commonalities Among the Blue Zones 10

• Largely plant‐based.• No over‐eating.• Foods are locally or home‐grown & home‐prepared. • Beans, including fava, black, soy and lentils, are the 

cornerstone of most centenarian diets.• 3 of the 5 zones are regular coffee consumers.• 4 of the 5 zones are regular alcohol consumers.• All 5 zones are regular consumers of grains & legumes.• Carbohydrate (largely from starch) is the predominant 

macronutrient. • None of the zones follow a very‐low‐carb/ketogenic diet.

Observational Evidence (Athletes): Dietary Habits of the World’s Endurance Champs11

• East African distance runners absolutely dominate the endurance game. Middle‐ and long‐distance runners from Kenya and Ethiopia hold over 90% of the all‐time world records and also the current top‐10 positions in world rankings. 

• Dietary habits of elite Ethiopian distance runners have recently been reported by Beis et al, here are the main findings [10]:

o Mean total energy intake:  3194 kcal.

o Protein was 12.4% (1.76 g/kg/day), 76% of which was plant‐derived. This leaves 23.3% of dietary energy as fat.

o The dominant macronutrient – by a large margin – was carbohydrate, at 64.3% of total kcal (9.7 g/kg/day). 

Observational Evidence:  My Clients

References1. Duncan R & Weston‐Smith M. The Nature of Knowledge by RA Lyttleton. 

The Encyclopaedia of Ignorance. Pergamon Press, 1977.2. Frigolet ME, Ramos Barragán VE, Tamez González M. Low‐carbohydrate 

diets: a matter of love or hate.  Ann Nutr Metab. 2011 Oct;58(4):320‐34.3. Westman EC, Feinman RD, Mavropoulos JC, Vernon MC, Volek JS, 

Wortman JA, Yancy WS, Phinney SD. Low‐carbohydrate nutrition and metabolism. Am J Clin Nutr. 2007 Aug;86(2):276‐84. 

4. Hession M, Rolland C, Kulkarni U, Wise A, Broom J. Systematic review of randomized controlled trials of low‐carbohydrate vs. low‐fat/low‐calorie diets in the management of obesity and its comorbidities. Obes Rev. 2009 Jan;10(1):36‐50.

5. Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogeniclow‐carbohydrate diets have no metabolic advantage over nonketogeniclow‐carbohydrate diets. Am J Clin Nutr. 2006 May;83(5):1055‐61.

References6. Hu T, Mills KT, Yao L, Demanelis K, Eloustaz M, Yancy WS Jr, Kelly TN, 

He J, Bazzano LA. ffects of low‐carbohydrate diets versus low‐fat diets on metabolic risk factors: a meta‐analysis of randomized controlled clinical trials. Am J Epidemiol. 2012 Oct 1;176 Suppl 7:S44‐54.

7. Cornier MA, Donahoo WT, Pereira R, Gurevich I, Westergren R, Enerback S, Eckel PJ, Goalstone ML, Hill JO, Eckel RH, Draznin B. Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women. Obes Res. 2005 Apr;13(4):703‐9.

8. Kreider RB, Wilborn CD, Taylor L, Campbell B, Almada AL, Collins R, Cooke M, Earnest CP, Greenwood M, Kalman DS, Kerksick CM, KleinerSM, Leutholtz B, Lopez H, Lowery LM, Mendel R, Smith A, Spano M, Wildman R, Willoughby DS, Ziegenfuss TN, Antonio J. ISSN exercise & sport nutrition review: research & recommendations. J Int Soc Sports Nutr. 2010 Feb 2;7:7.

References9. Rodriguez NR, DiMarco NM, Langley S; American Dietetic Association; 

Dietitians of Canada; American College of Sports Medicine: Nutrition and Athletic Performance. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. J Am Diet Assoc. 2009 Mar;109(3):509‐27.

10. Buettner D. The Blue Zones: Lessons for Living Longer From the People Who’ve Lived the Longest. Washington, DC: National Geographic Society; 2008.

11. Beis LY, Willkomm L, Ross R, Bekele Z, Wolde B, Fudge B, Pitsiladis YP. Food and macronutrient intake of elite Ethiopian distance runners. J IntSoc Sports Nutr. 2011 May 19;8:7. doi: 10.1186/1550‐2783‐8‐7.