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Friday, November 16, 2007

High fat diets are beneficial for endurance performance

"I have just found a study of runners and performance on high fat diets.
A Perspective on Fat Intake in Athletes David R. Pendergast, EdD, FACN, John J. Leddy, MD and Jaya T. Venkatraman, PhD
Journal of the American College of Nutrition, Vol. 19, No. 3, 345-350 (2000)
I'm really excited to see that the slow twitch muscle people (I mean people with higher percentage of slow twitch to fast) did really well on diets from 32-55% fat as far as their performance goes. The more I have been thinking about this whole carbo loading nonsense, the less sense it makes to me, even as the running community continues to advocate it along with a very low fat diet. So I'm going to keep a food journal as well as a training one as I prepare for my first half marathon race this autumn eating high fat (by that I mean highest percentage of daily calories from coming from fat). We shall see.

"Exercise training is generally associated with an increase in maximal aerobic power and endurance [3]. It is also generally agreed that the maximal potential for aerobic power and endurance is set genetically [3]. Any examination of the effects of dietary fat intake has to be considered in light of potential training effects. In studies of 25 male and female middle-aged endurance runners, with a long history of running, Vo2max did not significantly improve while running 40 to 50 miles per week for six months [44].

This same group of runners, when put on a high-fat diet, had a 3% to 8% increase in Vo2max (not significant) without a significant change in the peak heart rate observed in the max Vo2 test [47]. In a study on young elite endurance runners, a high-fat diet compared with a low-fat diet significantly increased Vo2max 8% to 12%, without a significant increase in the peak heart rate during the Vo2max test [35]. It should be noted that the diets in these two studies [35,43] were not randomized and cardiac output was not measured, so further work in this area is needed. Future work may also focus on the role of body fat distribution and the percentage of slow twitch oxidative muscle fibers in determining fat oxidation and endurance performance.

"Muscle fiber composition is important, as the potential for increased fat oxidation applies to slow twitch oxidative fiber metabolism. Thus, the higher the percentage of these fibers, the greater the potential benefits from the high-fat diet. It has recently been shown that experienced male runners (n=6, age=35±5 years), training 35 to 65 miles per week, consuming high dietary fat for one month (42%) had significantly increased in the volume density of total lipid in the muscle, without significant changes in the volume density of total mitochondria or total body weight and percent body fat [48].

Many athletes consume low calorie and low fat diets as a mechanism to reduce both fat intake and body weight [23,28]. Low caloric and/or fat intake diets may result in low levels of intramuscular fat stores that compromise performance."

Gary Moller comments:
While this is a controversial topic, I believe the fat free message that is currently the mantra of so many experts is a recipe for ill health. I was once in favour of the low fat diet, as all sports nutritionists seemed to be and most still are.
The drive to consume processed carbohydrates is now commercially driven by the food industry that makes billions worldwide through the sale of cheap carbohydrate foods and drinks derived from sources such as corn syrup that is then dollied up and on-sold at many times its actual cost. Low fat dairy is great for the dairy industry which strips the goodness out of the milk - sells us the milk water (while calling it milk) and then selling us the goodness as super-priced super foods (whey, creatine, colostrum etc) or as fortified milk water, such as Anlene. I would prefer real milk thanks - but where can you get it nowadays? Have public health officials have been seduced by industry propaganda and have they now adopted this fat-free mantra as their own, closing the shutters to good sense in the process?
While I do not have a problem with anybody making a profit, I do worry that athletes and the health conscious are being led down the wrong path. My take is this: Research that validates the benefits of carbohydrate-soaked diets is hardly ever short of funding as well as the publicity of their findings. Research that is to the contrary may have funding difficulties and any findings are likely to be buried, never to be published in the mass media including the sport magasines. We see similar patterns with chocolate and coffee. Of drugs for conditions like high blood pressure we hear little about the alternatives.
The study referred to in this article may be one of these that are buried. As young athletes, growing up in the late 1960's and early 1970's, we all trained the Lydiard Way, even if we did not realise it. The bread and butter part of the week was the weekend when we typically ran a short race like a lung-burning 3 mile cross-country and then ran a steady 2-3 hours through the Tokoroa bush on the Sunday morning on little more than a slice of toast with honey. Then we ravenously devoured the Sunday Roast!
Lydiard trained athletes were dominant back then and now I understand why. It has a lot to do with training the body to make best use of its fat reserves while conserving precious muscle glycogen which is needed for that withering home straight sprint. The intense racing on the Saturday depleted our muscle glycogen which takes 2-3 days to fully restore. Then we ran steady state less than a dozen hours later for a couple of hours or three, relying almost entirely on our fat reserves. We then packed in a rich supply of fat, protein and carbohydrate in the form of the Sunday roast and pudding. Do this for 12 weeks on the trot, Lydiard style, and you not only produce an athlete with the most completely developed aerobic setup; but also one with the most efficient fat metabolism. Lydiard always said that his athletes go faster as they work their way through the heats and semis, saving their best for the finals, while the opposition get progressively slower.
What Lydiard observed may be explained in part by the Lydiard trained athlete naturally conserving his or her muscle glycogen during competition. Without ample glycogen, the ability to run at pace, or to sprint is seriously compromised. Although Peter Snell was never the fastest sprinter in the fields, he consistently displayed the most withering finish. So did athletes like the Great miler - John Walker.
Nowadays, I have gone back to what I used to do: I run and cycle in training without food, ingesting plain water only. I have been doing this for the last couple of years. While it took three to four months for my body to adapt, it has been well worth the trouble. I am back to running and riding at my best which has been wonderful because I should be slowing with age. Instead, I am back to getting faster and doing this on less training than ever. While I have been doing several other things to keep the body ticking over properly, the fat/carbo thing is a most important part of the good health mix.
When doing intense competition that lasts more than about two hours, such as an extended mountain bike race, I might use a sugary electrolyte replacement like Balance Restore (; but most certainly not during lower-intensity training and recreational rides. The sugar shot is reserved for the high intensity, extended races. It works and it fits with this JACN study.
If you are doing relatively low intensity exercise that goes on for hours, such as a long hike, you are probably better served having a traditional farmer's breakfast consisting of bacon, eggs, sausages and baked beans on toast - plus a plate or two of porridge and a couple of cups of tea than having just a feed of nutritionally devoid pasta or bread and then relying on a sports drink to get you through.
As the JACN study indicates, performance is very much to do with calories consumed and there is no better source of calories than fat! When I worked on the farms of Putaruru, the day began at 4am milking the cows, followed by a big feed at 8am and then we worked steadily through the day doing hard labour before milking again at 3pm. That big breakfast is what got us through the day. More Calories In = More Calories Out.
Fat is essential for health and performance for more reasons than just plain calories: fat in the diet is essential for the supply and absorption of the fat soluble vitamins - E, D, A and K. Even if you supplement with vitamins, you still need fat to be healthy. Fat in the form of cholesterol provides the building blocks for the construction of hormones, like testosterone which men and women need to be strong and virile (A good reason for avoiding impotence-inducing statins). Cholesterol makes your cells robust and water proof.
Of course, there are fats and there are fats and one should be emphasising the consumption of healthy fats - but that is another article. In the meantime, avoid any kind of fat that is processed, like the hydrogenated ones that you find in the cheap cooking oils, margarines and cookies.

1 comment:

Wayne said...

the best endurance athletes can burn up to 1.15 grams of fat per minute from stored reserves most athletes burn less than .75 grams per minute, this can be taken from reserves.
I'd advise against eating anything that has fried fat in it, the fat you want is cold pressed vegetable oils. how much? I"d say experiment and see. i find 60 grams a day of sunflower seeds soaked in water is best for me and a tablespoon of fish oil, nothing else i've tried works as well, regardless of oil type or volume. at the end of the day carbs are easier to burn and essential fatty acids are the catalysts you need to burn the carbs. vegetable oils are easier to digest than animal fats.raw is more natural than cooked. cold pressed has less likelyhood to have been altered or damaged in processing.