Tag Archives: glycogen

Burn Fat for Fuel | The Paleo Diet

The marathon and triathlon seasons are fully underway and this year over half a million people will complete the marathon and thousands more participate in triathlons and other endurance events. Whether they’re entering an event for the first time or trying to achieve a personal best time, one of the most common questions I get asked by clients is “what should I eat before my long run?” The answer may surprise you!

A common refrain amongst most endurance coaches is that you must consume a heavy carbohydrate meal before your long run or bike to perform your best. High carbohydrate breakfasts of oatmeal, cereals, and juice or the classic ‘carb-load’ pasta dinner are staple recommendations from many top endurance coaches. While this is certainly not bad advice, there is another option.

Don’t eat any carbs before your long run or ride! (Yes, you heard me correctly.)

Let’s take a moment for a quick physiology review. When carbohydrates are ingested they are preferentially burned for fuel and provide 4 calories per gram of energy. When fats are ingested, or burned from body stores, they provide 9 calories per gram of fuel. You are effectively doubling your fuel efficiency if you use fat are your primary fuel source from the outset.

By maximizing your capacity to burn fat for fuel, you’ll also be sparing precious muscle glycogen, the carbohydrate stores in your muscle. You have approximately 500g of glycogen stored primarily in your muscles (and some in your liver) that can provide you with 2,000 calories of energy during your race. In contrast, even lean individuals between 7-14% body-fat have 20,000-30,000 calories available for energy use in their fat stores. Wow! That’s a lot of fuel that could be used, if you changed your pre-race food choices.

Skeptical? I don’t blame you, but the preliminary results are impressive.

Dr. Jeff Volek PhD is a world-renowned researcher and author of the FASTER (Fat-Adapated Substrate oxidation in Trained-Elite-Runners) study due to be released later this year. Dr. Volek and his team are investigating the impact of very low-carb diets on an athlete’s capacity to burn fat for fuel, compared to the traditional high-carb diets used by endurance athletes.

A traditional high carb diet would be broken down to approximately 60% carbs, 15% protein, and 25% fat. A low-carb diet would dramatically increase the fat intake to 70%, provide slightly more protein at 20%, and carbs would only make up 10% of the total daily energetic intake.

The initial data is sending shockwaves through the exercise community. Why?

It has been well established in the scientific literature for years that the maximum amount of body-fat that can be burned per minute is 1.0 grams, while the average athlete burns between 0.45-0.75g per minute. 1

The initial results from Dr Volek’s FASTER study smash this concept, showing the LCD athletes are burning upwards of 1.1-1.8g/minute which is way beyond what was thought physiologically possible. 2 You can see the peak fat oxidation or burning rates in the graph below.

Peak Fat Burning During VO2 Max

Traditionally, it was believed that somewhere between 35-65% of your maximum heart rate you switch from burning fat for fuel to carbohydrates. 3 However, this new research is re-shaping the way we think about fueling endurance athletes. The graph below highlights the body’s capacity to burn fat on a low-carb diet at much higher training intensities than thought possible. 2

Fat Oxidation Versus Exercise Intensity

If you ingest primarily carbohydrates your body quickly shifts over to burning the ingested carbs, and your body’s glycogen stores, for fuel. However, if you eat primarily fats and protein before exercise you’ll be able to tap into your fat reserves more effectively. This allows you to spare your muscle glycogen for further along in the race, when you really need it!

This new research is in-line with an ancestral or Paleo approach to eating. You don’t need to rely on an endless array of gels, powders, and pills to produce the best possible endurance race times. If you are engaging in endurance sports to lose weight this is critical, as your excess carbohydrate consumption is likely holding you back from achieving a better body and better health.

For example, you could start your day with a coffee and a tablespoon or two of coconut oil or MCT oil. The caffeine helps stimulate lipolysis, the breakdown of body-fat stores to free fatty acids for fuel and the MCTs provide the added instant energy source. Alternatively, you could have eggs with avocado and a serving a stir-fried kale or spinach. This will allow your body to burn fat for fuel more effectively, as well as improving your health.

Not everyone needs to follow a low-carb diet. If you are purely performance-based and striving for new personal bests than you may want to tread lightly. (Check out my previous article on Eating Enough Carbs Optimal Recovery to get your post-exercise carb fix). However, in a sport like endurance training where carbohydrates are king, this compelling new research highlights that we still have a ways to go in understanding how to most effectively fuel the body for endurance performance.

Train your body to burn more fat and watch your performance, as well as your health, reap the benefits!

 

REFERENCES

1. Venables et.al.; “Determinants of fat oxidation during exercise in healthy men and women: a cross-sectional study”. J Appl Physiol (1985) 2005 Jan;98(1):160-7.

2. Defty, President VESPA, Peter. “The Emerging Science on Fat Adaptation | Ultrarunning Magazine.” Ultrarunning Magazine The Emerging Science on Fat Adaptation Comments. Ultrarunning Magazine, 16 Dec. 2014. Web. 1 May 2015.

3. Lima-Silva A et al. Relationship between training status and maximal fat oxidation rate. J Sports Sci Med. 2010 Mar 1:9(1):31-5

4. Noakes, T., J.S. Volek, and S.D. Phinney. Low-carbohydrate diets for athletes: what evidence? British Journal of Sports Medicine. 48(14):1077-8, 2014.

Are You Eating Enough Carbs For Optimal Recovery?  | The Paleo Diet

While a low-carb Paleo diet is phenomenal for supporting weight loss and improving health if you are overweight, out of shape, or obese, not everyone is trying to lose weight.

For athletes training to achieve a personal best running a 10k, triathlon, or qualifying for the CrossFit Games, your eating strategy will not be one in the same.

Exercise is a catabolic process, triggering a release of stress hormones cortisol and adrenaline in order to raise blood sugars to fuel your activity. If you are exercising at a slow pace (less than 65% heart rate) your body has the time to use fat as a primary fuel source. However, as your exercise intensity increases your body quickly shifts to using muscle and liver glycogen (your body’s carb stores) to fuel exercise.

You have a limited capacity to store glycogen, which means after about 1-hour of training at a high intensity, you’ll likely have exhausted all your body’s glycogen stores.

WHAT’S THE MATTER WITH LOW GLYCOGEN STORES?

The research is quite clear that if you start your next training session with low or sub-optimal glycogen status, you’ll significantly reduce your capacity to work and your performance will suffer. A recent study of athletes who consumed only 40% of their total calories as carbohydrates and performed “two-a-day” training sessions suffered a significant decrease in their performance during the 2nd session because they did NOT adequately replenish muscle glycogen stores.1

If you are training at high intensity and following a low-carb diet, you are treading a fine line. If your goal is to be fit and lean, this isn’t really a problem. However, if your goal is optimizing your performance potential, eventually you will exhibit signs of overtraining and exhaustion.

Overtraining happens when you train intensely for too long, without adequate rest periods or tapers built into your training regime. While you do want to push yourself to the edge to stimulate a training adaptation (‘over-reaching’), you don’t want to push yourself over the edge!

Short-term symptoms of inadequate glycogen repletion include fatigue, reduced work capacity during training, poor recovery and extended delayed onset muscle soreness (DOMS). Long-term symptoms are pronounced fatigue, reduced strength levels and increased muscular weakness.

HOW CAN A PALEO DIET HELP IMPROVE RECOVERY AFTER EXERCISE?

The best way to replenish glycogen after training is to consume high-glycemic index (GI) carbs. High GI carbs enter the bloodstream quickly, allowing you to rapidly replenish glycogen stores in the first 30-60 minutes after training, when glycogen synthase enzyme activity is elevated and allows for optimal replenishment.2 Root vegetables make a great post-workout carb choice, especially if you bake them, which naturally raises the glycemic index of these foods, such as sweet potatoes, yams, yucca, plantains, carrots, beets, parsnips, etc.

If you are on the go and don’t have time to sit down for meal, try adding some dried fruit to your post-workout nutritional arsenal. Dried fruit is very high-glycemic, and while not ideal as a midday snack when sitting at your desk, it’s a great option after vigorous activity. Try 2-4 Medjool dates for 36-72g of carbs, or half a pack of dried mangos (1.5oz provides 36g of carbs).

The total amount of carbs you consume post-training depends on a few variables: your genetics, current body-fat percentage, training phase, etc. Aim for one gram of carbs per kilogram bodyweight in the first hour after exercise (divide your bodyweight in pounds by 2.2 to achieve your weight in kilograms).2,3 This can be repeated every two hours for up to 6 hours post-training for elite level trainees and sports that require two-a-day training, such as triathletes, Olympic weightlifters, and Ironman competitors.

In China, a recent study examined the effects of high-glycemic meals after exercise on performance in runners. The results showed athletes consuming high-GI meals post-training had significantly improved work capacity during their subsequent run four hours later.4 This highlights the importance for refilling your glycogen stores and ensuring your best performance in your next training session or race day.

WHAT HAPPENS IF YOU WAIT TO CONSUME YOUR CARBS POST-TRAINING?

Carbs directly replenish glycogen stores and after exercise your capacity to soak up carbs and top up glycogen is heightened. Research shows that if you wait several hours post-training you will reduce your glycogen repletion rate by as much as 50%!5 Not consuming enough carbs after exercise can also exacerbate inflammation, depress immunity, and lead to prolonged muscle soreness.6

If you’re already following a low-carb (LC) or very low-carb ketogenic (VLCK) diet you can still benefit by incorporating more carbs than normal post-training, without affecting your capacity to burn fat.7 For some, this may be the added boost you need to upgrade your performance. However, at higher intensity exercise the research shows a LC or VLCK diet does not likely support better performance.8

Remember, if you’re gearing up for a 10k run, triathlon, CrossFit Games or your competitive season, fatigue is directly related to muscle glycogen depletion when exercising at higher intensities. For optimal athletic performance, refuel with the right amount of carbs post-exercise and take your game to the next level.

Happy training!

 

 

REFERENCES

1. Ivy JL et al. Muscle glycogen storage after different amounts of carbohydrate ingestion. J Appl Physiol. 1988 Nov;65(5):2018-23.

2. Jentjens R, Jeukendrup A. Determinants of post-exercise glycogen synthesis during short-term recovery. Sports Med. 2003;33(2):117-44.

3. Ivy JL1.Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med. 1998 Jun;19 Suppl 2:S142-5.

4. Wong SH et al. Effect of glycemic index meals on recovery and subsequent endurance capacity. Int J Sports Med. 2009 Dec;30(12):898-905.

5. Jentjens R, Jeukendrup A. Determinants of post-exercise glycogen synthesis during short-term recovery. Sports Med. 2003;33(2):117-44.

6. Flakell PJ et al. Postexercise protein supplementation improves health and muscle soreness during basic military training in Marine recruits. J Appl Physiol 2004;96:951-956.

7. Burke LM, Hawley JA, Angus DJ, et al. Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability. Med Sci Sports Exerc 20002;34:83-91.

8. Antonio J, Kalman D, Stout S, et al. Essentials of Sports Nutrition and Supplements. International Society of Sports Nutritionists. Humana Press, NY 2008.

Ergogenic | The Paleo Diet

Many athletes worldwide, including those in the CrossFit community have adopted the Paleo Diet because they have observed that it helps them to increase muscle mass, reduce body fat and train at greater intensities. These characteristics ultimately result in enhanced performance. In a nutshell, there are four basic reasons why the Paleo Diet enhances athletic performance or is ergogenic.

1.Branched-chain amino acids

First, the diet is high in animal protein, which is the richest source of the branched-chain amino acids–valine, leucine, and isoleucine. Branched-chain amino acids (BCAA) are different from other amino acids that collectively make up protein in that they are potent stimulants for building and repairing muscle. This information is relatively new and has been reported in the scientific literature in the past decade or so. But the caveat is this: These amino acids work best when consumed in the post exercise window.

Lean meats and fish are far and away the greatest source of BCAA. A 1,000-calorie serving of lean beef provides 33.7 grams of BCAA, whereas the same serving of whole grains supplies a paltry 6 grams. Because many endurance athletes focus on starches (breads, cereals, pasta, rice, and potatoes) and sugars at the expense of meats, particularly following a hard workout, they get precious little muscle-building BCAA in their diets. By consuming high amounts of animal protein (and hence BCAA) along with sufficient carbohydrate, athletes can rapidly reverse the natural breakdown of muscle that occurs following a workout and thereby reduce recovery time and train at a greater intensity at the next session. Athletes worldwide who have adopted the Paleo Diet typically report of improved recovery with these dietary recommendations.

2. Blood acidity versus alkalinity

In addition to stimulating muscle growth via BCAA, the Paleo Diet simultaneously prevents muscle protein breakdown because it produces a net metabolic alkalosis. All foods, upon digestion, report to the kidney as either acid or alkali (base). The typical American diet is net acid producing because of its high reliance upon acid-yielding grains, cheeses, and salty processed foods at the expense of base-producing fruits and veggies. The athlete’s body is even more prone to blood acidosis due to the by-products of exercise. One way the body neutralizes a net-acid-producing diet is by breaking down muscle tissue. Because the Paleo Diet is rich in fruits and veggies, it reverses the metabolic acidosis produced from the typical grain-and starch-laden diet that many athletes consume, thereby preventing muscle loss.

3. Trace nutrients

Fruits and vegetables are also rich sources of antioxidant vitamins, minerals, and phytochemicals and, together with fresh meats (excellent sources of zinc and B vitamins), promote optimal immune-system functioning. The refined grains, oils, sugars, and processed foods that represent the typical staples for most athletes are nearly devoid of these trace nutrients. From examining the training logs of numerous people he has coached, my colleague and co-author, Joe Friel (an internationally known triathlete coach), has found that the frequency and duration of colds, flu, and upper respiratory illnesses are reduced when athletes adopt the Paleo Diet. A healthy athlete, free of colds and illness, can train more consistently and intensely and thereby improve performance.

4. Glycogen stores

One of the most important goals of any athletic diet is to maintain high muscle stores of glycogen, a body fuel absolutely essential for high-level performance. Dietary starches and sugars are the body’s number one source for making muscle glycogen. Protein won’t do, and neither will fat. Athletes and sports scientists have known this truth for decades. Regrettably, they took this concept to extremes; high-starch, cereal-based, carbohydrate-rich diets were followed with near-fanatical zeal 24 hours a day, 7 days a week.

It is a little known fact, but, similar to the situation with branched-chain amino acids, glycogen synthesis by muscles occurs most effectively in the immediate post-exercise window. Muscles can build all the glycogen they need when they get starch and sugar in the narrow time frame following exercise. Eating carbs all day long is overkill and actually serves to displace the muscle-building animal proteins and alkalinity-enhancing, nutrient-dense fruits and veggies that are needed to promote muscle growth and boost the immune system. Many Paleo friendly fruits and veggies are effective in restoring muscle glycogen, particularly net-alkaline-producing starches found in bananas, sweet potatoes, and yams.

Cordially,

Loren Cordain, Ph.D., Professor Emeritus

References

1. Anthony, J. C., Lang, C. H., Crozier, S. J., Anthony, T. G., MacLean, D. A., Kimball, S. R., and Jefferson, L. S. “Contribution of insulin to the translational control of protein synthesis in skeletal muscle by leucine.” American Journal of Physiology Endocrinology Metabolism, 2002; 282: E1092–101.

2. Ballmer, P. E., and Imoberdorf, R. “Influence of acidosis on protein metabolism.” Nutrition, 1995; 11:462–8.

3. Beelen M, Koopman R, Gijsen AP, Vandereyt H, Kies AK, Kuipers H, Saris WH, van Loon LJ. Protein coingestion stimulates muscle protein synthesis during resistance-type exercise. Am J Physiol Endocrinol Metab. 2008 Jul;295(1):E70-7. Epub 2008 Apr 22.

4. Beelen M, Burke LM, Gibala MJ, van Loon L JC. Nutritional strategies to promote postexercise recovery. Int J Sport Nutr Exerc Metab. 2010 Dec;20(6):515-32.

5. Calder, P. C., and Kew, S. “The immune system: a target for functional foods?” British Journal of Nutrition, 2002; 88 Suppl 2:S165–77.

6. Cordain, L. “The nutritional characteristics of a contemporary diet based upon Paleolithic food groups.” Journal of American Neutraceutical Association, 2002; 5:15–24.

7. Ferencik, M., and Ebringer, L. “Modulatory effects of selenium and zinc on the immune system.” Folia Microbiology (Praha), 2003; 48:417–26.

8. Frassetto, L., Morris, R. C., and Sebastian, A. “Potassium bicarbonate reduces urinary nitrogen excretion in postmenopausal women.” Journal of Clinical Endocrinology Metabolism, 1997; 82:254–59.

9. Hawley, J. A., Schabort, E. J., Noakes, T. D., and Dennis, S. C. “Carbohydrate-loading and exercise performance. An update.” Sports Medicine, 1997; 24:73–81.

10. Howarth KR, Moreau NA, Phillips SM, Gibala MJ. Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans. J Appl Physiol. 2009 Apr;106(4):1394-402. Epub 2008 Nov 26.

11. Koopman R, Pannemans DL, Jeukendrup AE, Gijsen AP, Senden JM, Halliday D, Saris WH, van Loon LJ, Wagenmakers AJ. Combined ingestion of protein and carbohydrate improves protein balance during ultra-endurance exercise. Am J Physiol Endocrinol Metab. 2004 Oct;287(4):E712-20. Epub 2004 May 27.

12. Layman, D. K. “Role of leucine in protein metabolism during exercise and recovery.” Canadian Journal of Applied Physiology, 2002; 27:646–62.
Lemon, P. W., Berardi, J. M., and Noreen, E. E. “The role of protein and amino acid supplements in the athlete’s diet: does type or timing of ingestion matter?” Current Sports Medicine Reports, 2002; 1:214–21.

13. Levenhagen, D. K., Gresham, J. D., Carlson, M. G., Maron, D. J., Borel, M. J., and Flakoll, P. J. “Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis.” American Journal of Physiology–Endocrinology and Metabolism, 2001; 280:E982–93.

14. May, R. C., Bailey, J. L., Mitch, W. E., Masud, T., and England, B. K. “Glucocorticoids and aci-dosis stimulate protein and amino acid catabolism in vivo.” Kidney International, 1996; 49:679–83.

15. Rasmussen BB, Tipton KD, Miller SL, Wolf SE, Wolfe RR. An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise.J Appl Physiol. 2000 Feb;88(2):386-92.

16. Remer, T. “Influence of nutrition on acid-base balance–metabolic aspects.” European Journal of Nutrition, 2001; 40:214–20.

17. Remer, T., and Manz, F. “Potential renal acid load of foods and its influence on urine pH.” Journal of the American Dietetic Association, 1995; 95:791–97.

18. Rowlands DS, Rössler K, Thorp RM, Graham DF, Timmons BW, Stannard SR, Tarnopolsky MA. Effect of dietary protein content during recovery from high-intensity cycling on subsequent performance and markers of stress, inflammation, and muscle damage in well-trained men. Appl Physiol Nutr Metab. 2008 Feb;33(1):39-51.

19. Saunders MJ. Coingestion of carbohydrate-protein during endurance exercise: influence on performance and recovery. Int J Sport Nutr Exerc Metab. 2007 Aug;17 Suppl:S87-103.

20. Thomson JS, Ali A, Rowlands DS. Leucine-protein supplemented recovery feeding enhances subsequent cycling performance in well-trained men. Appl Physiol Nutr Metab. 2011 Apr;36(2):242-53.

21. Tipton KD, Rasmussen BB, Miller SL, Wolf SE, Owens-Stovall SK, Petrini BE, Wolfe RR. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab. 2001 Aug;281(2):E197-206.

22. Valentine RJ, Saunders MJ, Todd MK, St Laurent TG. Influence of carbohydrate-protein beverage on cycling endurance and indices of muscle disruption. Int J Sport Nutr Exerc Metab. 2008 Aug;18(4):363-78.

Fruit Restriction | The Paleo Diet

People with type 2 diabetes are often advised by health professionals to limit fruit consumption to ensure greater glycemic control. A recent study has shown that the consumption of fruit does not result in adverse effects for participants with type 2 diabetes.

Effect of Fruit Restriction on Glycemic Control in Patients with Type 2 Diabetes – A Randomized Trial

Gluconeogenesis | The Paleo Diet

Dr. Cordain,

Hello there. I am sure you receive a generous amount of email, so I will not waste time with small talk and hope you actually get this email. Long story short: I earned my undergraduate in nutrition from University Nevada Reno in 2003. I left the world of academia with my general understanding of nutrition and felt ready to conquer the world of unhealthy eating ha! I have been doing a bit of research on the paleo diet as well as some others. I have been attempting to try out the paleo diet on myself as a sort of experiment. I had actually stopped eating grains for the most part about 5yrs ago, so it hasn’t been that difficult. What I am ultimately wondering is whether gluconeogenesis via the use of protein aka amino acids and efficient way to rebuild muscle glycogen (well liver glycogen and then to muscles). I just don’t want to be turning my wheels in the gym. It seems like maybe my body will adapt, but I have felt so fatigued at gym. I bonk within the 1st 15 20 min. Maybe I should add more carbs but it is difficult to know which carbohydrates I can eat. I’m not going to lie, I kind of want to just go eat a bowl of dairy filled ice cream and quickly revamp my glycogen. I am sure you are busy, but any help or resources would be greatly appreciated.

Sincerely,

Shilo

Dr. Cordain’s Response:

Hi,

Building glucose and then glycogen via gluconeogenesis is a very inefficient pathway. A better strategy is to obtain your carb stores as Joe Friel and I have outlined in our newly revised 2012, The Paleo Diet for Athletes. This book describes how Paleo foods such as sweet potatoes, yams, bananas, fresh fruit, fruit juices and dried fruit are both Paleo friendly and help to restore muscle glycogen. Additionally, we describe how to top off muscle glycogen before, during and after workouts and competition. Finally, by eliminating grains and refined carbs, you will force your body’s metabolic machinery to rely more upon stored intramuscular triglyceride (IMT) which will increase beta oxidation of IMT, which is a highly labile source of ATP during exercise. Higher muscle concentrations of IMT “spare” muscle glycogen and actually allow you additional time before muscle glycogen stores are depleted causing you to bonk. Many high level endurance athletes have successfully employed “Paleo” to improve performance.

Cordially,

Loren Cordain, Ph.D., Professor Emeritus

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