High-Carb vs Low-Carb Diet: Which Is Better for Athletes? Medscape article
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"High-Carb vs Low-Carb Diet: Which Is Better for Athletes?"
hould Diet Guidelines Be Revised?
Patrick Davitt, PhD, tries to keep carbohydrates down to 20% of the calories he consumes. You might think he's following one of the weight-loss regimens that became so popular a few years ago.
But Davitt already is slender and fit. In fact, he likes to run marathons, which puts his diet choice squarely in opposition to the recommendation of the American College of Sports Medicine (ACSM) that athletes start with the standard US Department of Agriculture guidelines of 45%-65% of energy from carbohydrates—then add more carbohydrates the more they exercise.[1,2]
An assistant professor of exercise science at Mercy College in Dobbs Ferry, New York, Dr Davitt argues that the official guidelines, which are now being revised, should describe the benefits of diets like his. "This should be provided as an option to athletes," he says.
The position has gained some recent traction as more and more studies show that the human body, once adapted to a low-carbohydrate diet, can fuel feats of endurance with energy stored in its own fat.
Dr Davitt presented one such study in May at the ACSM annual meeting.[3] He and his colleagues found that runners who adapt to a low-carbohydrate diet can burn up to 1.54 g of fat per minute, 50% more than the highest previous estimate. The athletes in this study had all run 50-mile races, and the study suggested that these athletes don't need energy bars and sports drinks.
High-Carb Advocates Aren't Convinced
But the low-carb advocates still haven't rooted out the sports world's deep commitment to carbohydrates. The ACSM's 2014 textbook for personal trainers suggests these menu options for a healthy breakfast when traveling: "Order pancakes, French toast, muffins, toast, cereal, fruit, and juices."[4]
Such recommendations are derived from research showing that people quickly burn up the glycogen in their muscles when they exercise, then use glucose in their blood. Without replacing that glucose, the thinking goes, an athlete will quickly run out of energy. And the human body can very quickly convert dietary carbohydrates to glucose.
"A single 30-second bout of high-intensity activity could reduce muscle carbohydrate (glycogen) storage by more than 25%," warns the personal trainer textbook. "By consuming a high-carbohydrate diet and carbohydrate-containing sports beverages, a client can improve energy reserves and enhance performances of repeated bouts of high-intensity activity."[4]
As a result, the American Dietetic Association, Dietitians of Canada, and the ACSM, in a position statement on nutrition and athletic performance, recommend 6-8 g of carbohydrates per kg of body weight per day, "depending on the athlete's total daily expenditure, type of sport performed, sex of the athlete, and environmental conditions." For a 150-pound person, that's roughly the equivalent of 10 slices of bread.[1]
It's no wonder that cross-country teams wolf down big pasta dinners the night before a meet or that empty sports drink bottles pile up on the sidelines of soccer games.
The Argument for Carbo-Loading
At least one author of the ACSM guidelines hasn't budged on her support for carbo-loading. "It's amazing how well athletes can do on a 50% carbohydrate diet," says Melinda M. Manore, PhD, RD, a professor of nutrition at the College of Public Health and Human Sciences at Oregon State University in Corvallis, Oregon. Dr Manore is one of the authors of the 2000 version of the guidelines and a reviewer for the 2009 version.
She doesn't dispute the findings of Dr Davitt and others that a person's metabolism will switch to burning fat at a higher rate after months on a low-carb diet. "Yes, we can increase fat oxidation and all those things," Dr Manore says. "But the diets are not palatable. People just don't want to go on a diet that's 50% fat or 70% fat."
Janet Rankin, PhD, associate dean of the graduate school and a professor in the Department of Human Nutrition, Foods, and Exercise at Virginia Tech University in Blacksburg, Virginia, agrees. She argues that there's simply no point to making the switch to a low-carb metabolism.
"There has been interesting and well-done research showing that eating a lower-carbohydrate diet is successful at boosting fat use during an exercise bout," she says. "The problem I have is that there is virtually no evidence I can find that this enhances performance. Many studies show benefits of a high-carbohydrate diet for performance."
The Argument for a Low-Carb Diet
For the most part, Dr Davitt is not making the argument that a low-carb diet will boost performance. In his study, the low-carb distance runners only matched the performance of the high-carb runners.
But he sees the energy bars and sports drinks as a kind of crutch. Some people upset their gastrointestinal systems if they try to eat while exercising, Dr Davitt points out. They waste valuable time in portable toilets during marathons. Others just don't want to carry anything with them or make too many stops.
"The other argument is about health," he says. "There is not a lot of research on long-term effects of consuming these high-carbohydrate drinks in athletes. But if you look at the research, it's going to cause a spike in glucose, and the spike in glucose is going to cause a spike in insulin, which could potentially have downstream effects or long-term effects on the whole-body physiology."
Intake of sugar—the energy source in sports drinks—may be particularly problematic. In one recent study, children with metabolic syndrome reduced the sugar in their diets from 28% of calories to 10% of calories, substituting the same number of calories in starch. They experienced improvements in their diastolic blood pressure as well as levels of lactate, triglycerides, low-density lipoprotein cholesterol, glucose tolerance, and hyperinsulinemia.[5]
Dr Davitt sees other benefits to a low-carbohydrate diet, too: "lower inflammatory responses, decreased recovery time, health benefits to the microbiome in the gut."
The Controversy Over Saturated Fat
In response, Dr Manore points out that such studies weren't done in athletes. "People who are physically fit and active are different from sedentary, overweight Americans," she says. "There are certain situations where the sugar is beneficial. But we don't make the recommendation until they have been out exercising 60-90 minutes."
Besides, if athletes aren't eating carbohydrates, Dr Manore worries about where they are getting their calories. There are dangers to excessive fat—particularly saturated fats, she argues.
That assertion leads into one of the hottest controversies in nutrition. Until recently, the most prominent writers of nutrition guidelines in the United States believed that eating too much saturated fat can increase the risk for cardiovascular disease.[6]
But recent systematic literature reviews have poked holes in the evidence behind that position.[7,8] And the questioning has already led to tentative revisions in another set of influential guidelines: the Dietary Guidelines for Americans.[2]
In a report on how these guidelines should be updated for 2015, the influential Dietary Guidelines Advisory Committee in February called for specific limits on sugar intake and looser limits on saturated fat and cholesterol than in previous versions of the guidelines.[6] The report even mentions a low-carb diet among several proven weight-loss approaches.
The Nutrition and Athletic Performance guidelines of the ACSM and its partner organizations in the past have cited the Dietary Guidelines for Americans in their discussion of carbohydrates.[1]
Will the shift in thinking influence the updates planned for March 2016? Dr Manore, who has reviewed drafts, isn't telling prior to publication. But whichever side the authors choose, it's clear that the controversy won't end any time soon."
References
1 American Dietetic Association; Dietitians of Canada; American College of Sports Medicine, Rodriguez NR, Di Marco NM, Langley S. American College of Sports Medicine position stand. Nutrition and athletic performance. Med Sci Sports Exerc. 2009;41:709-731. Abstract
2 US Department of Agriculture. Dietary guidelines for Americans 2005. Chapter 7 Carbohydrates. Updated July 9, 2008. http://health.gov/dietaryguidelines/dga2005/document/html/chapter7.htm Accessed December 3, 2015.
3 Harrison L. Endurance runners on low-carb diet burn fat. Medscape Medical News. June 11, 2015. http://www.medscape.com/viewarticle/846278 Accessed December 3, 2015.
4 American College of Sports Medicine. ACSM's Resources for the Personal Trainer. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.
5 Lustig RH, Mulligan K, Noworolski SM, et al. Isocaloric fructose restriction and metabolic improvement in children with obesity and metabolic syndrome. Obesity (Silver Spring). 2015 Oct 26. [Epub ahead of print]
6 US Department of Health & Human Services. Scientific report of the 2015 Dietary Guidelines Advisory Committee. Part B: Chapter 2: 2015 DGAC themes and recommendations: integrating the evidence. December 3, 2015. http://health.gov/dietaryguidelines/2015-scientific-report/04-integration.asp Accessed December 3, 2015.
7 de Souza RJ, Mente A, Maroleanu A, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systemic review and meta-analysis of observational studies. BMJ. 2015;351:h3978.
8 Hooper L, Summerbell CD, Thompson R, et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. 2012;5:CD002137.
Some take-home points:
Reassuring that athletes/active people don't necessarily apply to the saturated fat dogma
Not much research on High carb diets being detrimental to athletes (athletes seem to have immunity from dietary lifestyles)
Low carb diets don't equate to better athletic performance vs. high carb diets but appear to have better long term health benefits
"High-Carb vs Low-Carb Diet: Which Is Better for Athletes?"
hould Diet Guidelines Be Revised?
Patrick Davitt, PhD, tries to keep carbohydrates down to 20% of the calories he consumes. You might think he's following one of the weight-loss regimens that became so popular a few years ago.
But Davitt already is slender and fit. In fact, he likes to run marathons, which puts his diet choice squarely in opposition to the recommendation of the American College of Sports Medicine (ACSM) that athletes start with the standard US Department of Agriculture guidelines of 45%-65% of energy from carbohydrates—then add more carbohydrates the more they exercise.[1,2]
An assistant professor of exercise science at Mercy College in Dobbs Ferry, New York, Dr Davitt argues that the official guidelines, which are now being revised, should describe the benefits of diets like his. "This should be provided as an option to athletes," he says.
The position has gained some recent traction as more and more studies show that the human body, once adapted to a low-carbohydrate diet, can fuel feats of endurance with energy stored in its own fat.
Dr Davitt presented one such study in May at the ACSM annual meeting.[3] He and his colleagues found that runners who adapt to a low-carbohydrate diet can burn up to 1.54 g of fat per minute, 50% more than the highest previous estimate. The athletes in this study had all run 50-mile races, and the study suggested that these athletes don't need energy bars and sports drinks.
High-Carb Advocates Aren't Convinced
But the low-carb advocates still haven't rooted out the sports world's deep commitment to carbohydrates. The ACSM's 2014 textbook for personal trainers suggests these menu options for a healthy breakfast when traveling: "Order pancakes, French toast, muffins, toast, cereal, fruit, and juices."[4]
Such recommendations are derived from research showing that people quickly burn up the glycogen in their muscles when they exercise, then use glucose in their blood. Without replacing that glucose, the thinking goes, an athlete will quickly run out of energy. And the human body can very quickly convert dietary carbohydrates to glucose.
"A single 30-second bout of high-intensity activity could reduce muscle carbohydrate (glycogen) storage by more than 25%," warns the personal trainer textbook. "By consuming a high-carbohydrate diet and carbohydrate-containing sports beverages, a client can improve energy reserves and enhance performances of repeated bouts of high-intensity activity."[4]
As a result, the American Dietetic Association, Dietitians of Canada, and the ACSM, in a position statement on nutrition and athletic performance, recommend 6-8 g of carbohydrates per kg of body weight per day, "depending on the athlete's total daily expenditure, type of sport performed, sex of the athlete, and environmental conditions." For a 150-pound person, that's roughly the equivalent of 10 slices of bread.[1]
It's no wonder that cross-country teams wolf down big pasta dinners the night before a meet or that empty sports drink bottles pile up on the sidelines of soccer games.
The Argument for Carbo-Loading
At least one author of the ACSM guidelines hasn't budged on her support for carbo-loading. "It's amazing how well athletes can do on a 50% carbohydrate diet," says Melinda M. Manore, PhD, RD, a professor of nutrition at the College of Public Health and Human Sciences at Oregon State University in Corvallis, Oregon. Dr Manore is one of the authors of the 2000 version of the guidelines and a reviewer for the 2009 version.
She doesn't dispute the findings of Dr Davitt and others that a person's metabolism will switch to burning fat at a higher rate after months on a low-carb diet. "Yes, we can increase fat oxidation and all those things," Dr Manore says. "But the diets are not palatable. People just don't want to go on a diet that's 50% fat or 70% fat."
Janet Rankin, PhD, associate dean of the graduate school and a professor in the Department of Human Nutrition, Foods, and Exercise at Virginia Tech University in Blacksburg, Virginia, agrees. She argues that there's simply no point to making the switch to a low-carb metabolism.
"There has been interesting and well-done research showing that eating a lower-carbohydrate diet is successful at boosting fat use during an exercise bout," she says. "The problem I have is that there is virtually no evidence I can find that this enhances performance. Many studies show benefits of a high-carbohydrate diet for performance."
The Argument for a Low-Carb Diet
For the most part, Dr Davitt is not making the argument that a low-carb diet will boost performance. In his study, the low-carb distance runners only matched the performance of the high-carb runners.
But he sees the energy bars and sports drinks as a kind of crutch. Some people upset their gastrointestinal systems if they try to eat while exercising, Dr Davitt points out. They waste valuable time in portable toilets during marathons. Others just don't want to carry anything with them or make too many stops.
"The other argument is about health," he says. "There is not a lot of research on long-term effects of consuming these high-carbohydrate drinks in athletes. But if you look at the research, it's going to cause a spike in glucose, and the spike in glucose is going to cause a spike in insulin, which could potentially have downstream effects or long-term effects on the whole-body physiology."
Intake of sugar—the energy source in sports drinks—may be particularly problematic. In one recent study, children with metabolic syndrome reduced the sugar in their diets from 28% of calories to 10% of calories, substituting the same number of calories in starch. They experienced improvements in their diastolic blood pressure as well as levels of lactate, triglycerides, low-density lipoprotein cholesterol, glucose tolerance, and hyperinsulinemia.[5]
Dr Davitt sees other benefits to a low-carbohydrate diet, too: "lower inflammatory responses, decreased recovery time, health benefits to the microbiome in the gut."
The Controversy Over Saturated Fat
In response, Dr Manore points out that such studies weren't done in athletes. "People who are physically fit and active are different from sedentary, overweight Americans," she says. "There are certain situations where the sugar is beneficial. But we don't make the recommendation until they have been out exercising 60-90 minutes."
Besides, if athletes aren't eating carbohydrates, Dr Manore worries about where they are getting their calories. There are dangers to excessive fat—particularly saturated fats, she argues.
That assertion leads into one of the hottest controversies in nutrition. Until recently, the most prominent writers of nutrition guidelines in the United States believed that eating too much saturated fat can increase the risk for cardiovascular disease.[6]
But recent systematic literature reviews have poked holes in the evidence behind that position.[7,8] And the questioning has already led to tentative revisions in another set of influential guidelines: the Dietary Guidelines for Americans.[2]
In a report on how these guidelines should be updated for 2015, the influential Dietary Guidelines Advisory Committee in February called for specific limits on sugar intake and looser limits on saturated fat and cholesterol than in previous versions of the guidelines.[6] The report even mentions a low-carb diet among several proven weight-loss approaches.
The Nutrition and Athletic Performance guidelines of the ACSM and its partner organizations in the past have cited the Dietary Guidelines for Americans in their discussion of carbohydrates.[1]
Will the shift in thinking influence the updates planned for March 2016? Dr Manore, who has reviewed drafts, isn't telling prior to publication. But whichever side the authors choose, it's clear that the controversy won't end any time soon."
References
1 American Dietetic Association; Dietitians of Canada; American College of Sports Medicine, Rodriguez NR, Di Marco NM, Langley S. American College of Sports Medicine position stand. Nutrition and athletic performance. Med Sci Sports Exerc. 2009;41:709-731. Abstract
2 US Department of Agriculture. Dietary guidelines for Americans 2005. Chapter 7 Carbohydrates. Updated July 9, 2008. http://health.gov/dietaryguidelines/dga2005/document/html/chapter7.htm Accessed December 3, 2015.
3 Harrison L. Endurance runners on low-carb diet burn fat. Medscape Medical News. June 11, 2015. http://www.medscape.com/viewarticle/846278 Accessed December 3, 2015.
4 American College of Sports Medicine. ACSM's Resources for the Personal Trainer. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013.
5 Lustig RH, Mulligan K, Noworolski SM, et al. Isocaloric fructose restriction and metabolic improvement in children with obesity and metabolic syndrome. Obesity (Silver Spring). 2015 Oct 26. [Epub ahead of print]
6 US Department of Health & Human Services. Scientific report of the 2015 Dietary Guidelines Advisory Committee. Part B: Chapter 2: 2015 DGAC themes and recommendations: integrating the evidence. December 3, 2015. http://health.gov/dietaryguidelines/2015-scientific-report/04-integration.asp Accessed December 3, 2015.
7 de Souza RJ, Mente A, Maroleanu A, et al. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systemic review and meta-analysis of observational studies. BMJ. 2015;351:h3978.
8 Hooper L, Summerbell CD, Thompson R, et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. 2012;5:CD002137.
Some take-home points:
Reassuring that athletes/active people don't necessarily apply to the saturated fat dogma
Not much research on High carb diets being detrimental to athletes (athletes seem to have immunity from dietary lifestyles)
Low carb diets don't equate to better athletic performance vs. high carb diets but appear to have better long term health benefits
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Reassuring that athletes/active people don't necessarily apply to the saturated fat dogma
Not much research on High carb diets being detrimental to athletes (athletes seem to have immunity from dietary lifestyles)
Low carb diets don't equate to better athletic performance vs. high carb diets but appear to have better long term health benefits
Don't know if you caught the thread on Volek's FASTER study, but there are some links to interviews with Zach Bitter in there. The digestion and stomach upset issues are a big deal for endurance athletes. That's probably the most immediate benefit to the LC switch. I've heard lots of horror stories about bathroom breaks and vomit breaks in the middle of a long-distance event.
The reduction in oxidative stress has got to be a HUGE long-term win. But we probably won't know for sure for another 40 or so years....0 -
Love this! My trainer is the one who introduced me to LCHF and I've been eating this way for 18 months now. It took some time to adjust mentally, but as I have tightened my macros I've felt better and better. Thanks so much for posting this, I'll find it online & share!0
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"Yes, we can increase fat oxidation and all those things," Dr Manore says. "But the diets are not palatable. People just don't want to go on a diet that's 50% fat or 70% fat."
Speak for yourself, lady. I'd much rather have a nice, juicy steak than a bland dish of spaghetti that won't fill me up and will leave me hungry in a couple of hours.For the most part, Dr Davitt is not making the argument that a low-carb diet will boost performance. In his study, the low-carb distance runners only matched the performance of the high-carb runners.
Low carb runners "only" matched the performance of high-carb runners, without needing to refuel multiple times during the race.
Not allow people to refuel every few miles and let's see who comes out on top then."A single 30-second bout of high-intensity activity could reduce muscle carbohydrate (glycogen) storage by more than 25%," warns the personal trainer textbook. "By consuming a high-carbohydrate diet and carbohydrate-containing sports beverages, a client can improve energy reserves and enhance performances of repeated bouts of high-intensity activity."[4]
But...but...but....marathon runners aren't doing high-intensity activity (at least not on the distance runs). They do an "all-day pace," which is like 60% of max or something like that. Right in the "fat-burning zone" and prime range for a fat-adapted runner.
*facepalm*Janet Rankin, PhD, associate dean of the graduate school and a professor in the Department of Human Nutrition, Foods, and Exercise at Virginia Tech University in Blacksburg, Virginia, agrees. She argues that there's simply no point to making the switch to a low-carb metabolism.
Allow me to introduce you to the Columbus Crew SC, Major League Soccer team. Second in the league in 2015, Conference Finals winners, and MLS Cup team. Oh, and they follow LCHF.
http://614columbus.com/2015/05/the-one-two-punch/
http://www.mlssoccer.com/post/2015/11/26/how-remaining-mls-cup-playoff-clubs-are-doing-thanksgiving-sideline
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