Experience From - Steve Pero , Dan Baglione , Karl King , Bruce Ketchum , Robert Thomas#1 , Paul Schmidt Exercise Physiologist, M.S. , Robert Thomas#2 ,

Steve Pero

With many of the discussions on fat and bacon and eggs, etc., I thought I'd send along this interesting tidbit I recieved the other day.

High-Fat Diet Heart-Safe for Runners

NEW YORK (Reuters) -- Athletes who train on a high-fat diet have healthier cholesterol profiles than when they eat a traditional low-fat, high-carbohydrate training diet, researchers say.

The new study found higher HDL -- "good" cholesterol -- levels among runners who ate more fat during training, compared with those who trained on a low-fat diet. Moreover, LDL -- "bad" cholesterol -- and total cholesterol levels in the high-fat diet group remained unchanged.

Researchers from the State University of New York at Buffalo where the study was conducted say the runners neither gained weight nor increased their body fat when they boosted their consumption of dietary fat. They note their findings applied to both male and female runners.

"Liberalizing the fat content gives athletes more calories, and it certainly doesn't harm their health, like everyone thought," says Dr. John Leddy, associate director of the University's Sports Medicine Institute and lead researcher for the study. "We thought the cholesterol ratio would get worse, but LDL and total cholesterol didn't change, and HDL went up. The best thing happened that could have happened."

According to the Buffalo team, the study could have important implications for anyone who puts in high running mileage for health purposes. It shows they may be blunting the benefits of running by eating a diet too low in fat.

The study included 12 male and 13 female competitive runners who trained at least 35 miles a week. The men averaged 36 years of age, and the women averaged 33 years.

Participants spent a month on their normal diets, followed by one month each on diets composed of 16% and 30% fat. Six males and six females spent an additional month on a 42%-fat diet. Protein intake remained stable at 15% and carbohydrates made up the difference in the diets.

Researchers measured resting heart rate and blood pressure, as well as blood levels of total cholesterol, HDL and LDL cholesterol, triglycerides, and the major protein components of HDL and LDL.

Results showed that HDL levels rose as the amount of fat in the diets increased. There was no change in weight, percentage of body fat, heart rate, blood pressure, triglycerides, total cholesterol, or LDL.

Surprisingly, the 42%-fat diet decreased the risk factors for coronary heart disease, while the 16%-fat diet increased the risk factors by lowering levels of HDL and the main protein component of HDL. High HDL levels are considered protective against heart disease.

Leddy says the underlying mechanism causing this effect is still in question, but he suggests it may involve the activity of the enzyme lipoprotein lipase.

"Trained athletes have higher levels of this enzyme, which breaks down dietary fat and, in the process, removes plasma triglycerides and forms HDL. If dietary fat is restricted, lipoprotein lipase activity is inhibited," he explains.

"Also, dietary fat increases the production of the major HDL protein (apo 1), so dietary fat restriction would mean less HDL protein is formed. Both mechanisms could reduce the beneficial effect training has on HDL levels," Leddy notes.

"I think these results are particularly important to female athletes," he adds. "Gymnasts, runners and swimmers, for example, tend to be very concerned about weight gain." He notes that female athletes who consume too few calories to support the energy they expend are at risk for the triad of eating disorders, amenorrhea (no menstrual period), and osteoporosis (bone thinning).

According to Leddy, it isn't the fat, per se, that keeps these athletes healthy; it's eating enough food to supply the body with as many calories as they expend in training -- a nearly impossible feat without including foods high in fat, he points out.

"This study shows that if they are burning up the calories, it doesn't matter where the calories come from, and it appears that a very low-fat diet is clearly detrimental," the researcher says.

But nonathletes should not view this as an invitation to disregard the amount of fat in their diets. "It remains to be seen if sedentary, nonobese subjects, who maintain caloric balance (at lower energy flux) will respond to dietary fat over prolonged periods as have these runners," conclude the study authors. SOURCE: Medicine and Science in Sports and Exercise

Dan Baglione

For the first 14 years of my running I consumed a high fat diet and ran more miles than I have been running for the last 6 years and at faster pace.

Just over 6 years ago it was discovered that I had coronary artery disease and a cholesterol of 275. I had angioplasty and have been on a low fat diet ever since. Some vegetarian runners and walkers I know consume even less fat than I and have higher HDL than I.

I would not get too secure about a high fat diet on the basis of one study with few participants all or most of whom are competitive runners.

Karl King

Phil Sheridan asked how much fat he should have for a 100.

If you get 50% of your calories from body fat, you'll need a little over a pound of fat for a 100 miler. So, it doesn't make sense to pack on lots of blubber just because you're running long ultras. Most of us can find an extra pound or two of fat to spare for the 100 miler.

For those who have very low body fat, there is a more subtle concern. The body maintains pockets of essential fatty acids for use in immune system function. If you have very low body fat, AND run ultras, you can take away from those fat reserves which are necessary for good immune system function. The result can be greater susceptibility to illness after an ultra or hard course of training.

Some diet programs call for ultra-low levels of fat. Those will probably be shown to compromise immune system function. The happy medium is likely in between the ultra-low fat diets and the typical American high-fat diet.

If you insist on a low fat diet, you would likely have better immune system function if you took essential fatty acid supplements such as flax and borage oil.

Every so often we hear of a runner who switched to a low-fat diet and had better performances. That is not surprising if they were eating a high fat diet before. The danger lies some months down the road when the body has drawn down its supplies of essential fatty acids. Then general health can suffer.

Modest amounts of high quality fats are neccessary for good health. Extremes of very low fat or the typical low quality high fat American diet are not healthy.

Eat good food, and you'll have enough body fat for any ultra distance.

Bruce Ketchum

A few words on fat metabolism.

Have you ever seen a fat sprinter? No, because they utilize fat stores very well also, just not quite in the same manner as an endurance athlete. It1s not just exercise in that so-called 3fat burning zone2 that will burn fat, any activity at any intensity burns fat. Maybe not directly but in the end, fat will be used up. Let me explain. At the very most, about 50% of your calories that your body needs and uses can come from the oxidation of fat. The other half of the calories needed at this time come mostly from carbohydrate. This 50% fat, 50% carbohydrate use occurs only during rest, like during sleep or long periods in front of the TV. Just getting up, although more calories are expended, will lower the percentage of fat calories used. As the intensity of exercise increases, lets say from a slow walk all the way up to a maximal sprint, the rate of fat use is inversely related and the use of carbohydrate is directly affected (See graph). Although a higher ratio of carbohydrate is used as the intensity goes up, fat is still used. It is not until you reach near maximal effort that energy use comes solely from the combustion of carbohydrate. Now I1m sure this idea isn1t new to you, but it does illustrate that fat is burned, at least to some extent, during most exercise intensity levels. This, however, is not the main way or reason that high intensity exercise will burn fat effectively.

Overall, during high intensity exercise, more calories are used, creating a calorie deficit in the muscles and liver which can only be filled in two ways:

  1. Dietary energy sources can replenish a calorie deficit. When you eat a meal that contains carbohydrate and fat, these nutrients are shuttled off to where they are needed. Muscle cells that have had their energy stores depleted will be the first place these nutrients go to. Once the muscles are topped off with these two nutrients, the remaining dietary carbohydrate will go to the liver to be stored as glycogen, and once the liver is also topped off the rest of the carbohydrate will go to fat cells and be converted to fat. Like the carbohydrate, dietary fat will also travel to the depleted muscles and then to the liver where it is converted to carbohydrate if there isn1t enough carbohydrate available from the diet. Once that is complete the remaining dietary fat will be stored in fat cells. What I've just presented is not so cut and dry as this, however. While dietary carbohydrate and fat do go to the needed muscle cells, they also, at the same time, go to the liver, and to fat cells to some extent, as well. It1s just that these dietary nutrients are mainly (preferentially) shipped to the depleted muscle tissues, but some does sneak through and get to the liver and fat cells.

  2. Breaking down body fat and protein can also replenish a calorie deficit in muscle and the liver. Fat from adipose tissue is redistributed to muscle where it is used for either immediate energy or stored as muscle triglycerides; or this fat can travel to the liver to be converted to carbohydrate where it can then be circulated to muscle to be used immediately or stored as muscle glycogen. When the muscles don1t need anymore of this converted carbohydrate the rest is simply stored in the liver as glycogen or sent back to adipose tissue.

With the above two scenarios understood, you can see how just burning carbohydrate can potentially lead to the burning of fat. Carbohydrate stores are low, so the body breaks down fat and turns it into carbohydrate to replace those stores. That1s why it is so important to avoid fat during a diet in which you are trying to lower body fat. By not providing dietary fat in the diet, the body is forced to take its stored fat and redistribute it to muscle or convert it to carbohydrate. Also, restricting dietary carbohydrate forces the body to mobilize more fat from its stores and send it to the liver to be turned into carbohydrate.

Finally, because high intensity exercise is very demanding on the body, it leaves the body in a revved up state or accelerated metabolic state that also burns a lot of fat and carbohydrate. Again, contributing to the calorie deficit, and contributing to the ultimate goal: shedding body fat stores.

As an endurance athlete, you can1t just stop training aerobically and take up high intensity exercise to burn fat. That would be counter productive. Instead, during your long rides or runs, do some hard efforts. Jam up a steep hill, go hard to the next light post, or challenge a friend to a sprint. To finalize your workout and ensure that you are optmizing your fat loss program, end the training with some tough efforts like some fast 200-400 meter runs or bike sprints around the block. This will leave your engine running faster, burning not only fat but carbohydrate as well.

A successful fat loss program not only restricts the intake of fat and carbohydrate, it uses exercise of all intensities to further create that desired caloric deficit which ultimately will cause the performance-impairing pounds to melt away,

Robert Thomas #1

Fats are to my thinking are one of the most difficult areas in nutrition to have clear cut answers for. There needs to be a lot more research to be able to clearly understand all the health implications concerning all the different forms of fat and all these different forms interrelationships with all other food elements.

That having been said I would recommend reading "Fats That Heal Fats that Kill", really a very fine book, filled with a tremendous amount of information. After reading it there was only one small point I disagreed with in a small way and one omission, the author promotes flax seed derived oil over fish oil. There are problems with fish oil related to rancidity and contamination, but if you use quality fish oil, it can be more effective than flax oil for the health reasons you use it for. The author also sells a flax oil product so he does have a financial interest in promoting flax oil. Also there is no information about conjugated linoleic acid, this is an unfortunate omission.

To answer the main point of your question, fats have tremendously powerful effect in the body, the types and amounts you eat directly relate to your health in a powerful way. What the research literature has shown is an every mounting evident that generally speaking trans fatty acids are at the root of many different health problems. There are a few experts that would disagree with that statement, but there are also in every increasing numbers experts that think trans fats are unhealthy for you.

Here are a few facts and statements from "Fats That Heal".

The Dutch government has banned the sale of margarine's that contain trans-fatty acids.

A statement from Herbert Dutton one of the oldest and most knowledgeable oil chemists in North America, it goes something like this: If the hydrogenation process were discovered today, it probably could not be adopted by the oil industry. The basis of this for such a comment lies in the recent awareness of our prior ignorance concerning the complexity of isomers formed during hydrogenation and their metabolic and physiological fate.

A Boston researcher Mary Enig has examined the effects of trans-fatty acids for many years. Basically she has found that trans fats, alter membrane transport and fluidity, alter the activities of liver enzyme systems that metabolize carcinogens, decrease insulin response, increase blood insulin in response to glucose, correlate with low birth weight in humans, decrease testosterone and increase abnormal sperm (in animals). I could go on but you get the point.

There is a long history of use with trans-fatty acid and a very powerful oil lobby in Washington keeping the status quo, that's the way it is.

I find it very interesting how just one percent in the diet of Conjugated Linoleic acid, has been shown to have very strong anti carcinogenic effects, helps reduce body fat and improve the anabolic effect. It just confirms the power of a small amount of particular fat, be it for good health or bad.

So don't eat trans-fatty acids and do eat fish like salmon or take a high quality fish oil supplement, have flax oil also. There is another family of fatty acids (GLA) to have in the diet, supplementing with borage oil takes care of that. So there are three main oils to supplement the diet with, high quality fish oil (w3), borage oil (GLA), conjugated linoleic acid.

On top of that don't eat oxidized oils of any type, if you can help it, don't eat fried foods, or oils that have been opened and left in the refrigerator for very long. Hamburger is a good example, after it has been left in the refrigerator for a few days in goes rancid and smells this is easy to see and smell. Polyunsaturated fats from vegetable source's can go rancid more easily that the fats in meats like hamburger, but rancid polyunsaturated oil are hard to detect with are senses, they don't look bad or smell bad until their really oxidized (rancid) a lot.

A good healthy diet makes you feel better. Running to everything we do in our lives is better if we feel at are best health.

Paul Schmidt Exercise Physiologist, M.S.

Bruce Ketchum wrote:

"Breaking down body fat and protein can also replenish a calorie deficit in muscle and the liver. Fat from adipose tissue is redistributed to muscle where it is used for either immediate energy or stored as muscle triglycerides; or this fat can travel to the liver to be converted to carbohydrate where it can then be circulated to muscle to be used immediately or stored as muscle glycogen. When the muscles don1t need anymore of this converted carbohydrate the rest is simply stored in the liver as glycogen or sent back to adipose tissue.

With the above two scenarios understood, you can see how just burning carbohydrate can potentially lead to the burning of fat. Carbohydrate stores are low, so the body breaks down fat and turns it into carbohydrate to replace those stores. That1s why it is so important to avoid fat during a diet in which you are trying to lower body fat. By not providing dietary fat in the diet, the body is forced to take its stored fat and redistribute it to muscle or convert it to carbohydrate. Also, restricting dietary carbohydrate forces the body to mobilize more fat from its stores and send it to the liver to be turned into carbohydrate.

Not exactly!

Tryglycerides that are stored in fat cells or skeletal muscle fiber are broken down into glucerol and free fatty acids (FFA) in a process called lipolysis. The glycerol then travels via the blood and enters into muscle fibers due by diffusion. The rate at which this ocurrs depends on the on concentration gradient (difference). Upon entering the muscle fibers the FFA is further broken down via beta oxidation to form acetic acid CoA. At this point, fat metabolism follows the same path as carbohydrates (Krebs cycle).

The main difference is that complete combustion of FFA requires a lot more oxygen. Therefore, although fat provides more kcal of energy per gram than carbohydrates, fat metabolism is limited by oxygen delivery. So..... class no pay attention, there will be a test, CARBOHYDRATE is the preferred fuel during high intensity exercise.

Robert Thomas #2

After reading the posts on Fat Metabolism, I thought maybe just a brief and simple way to look at the body's energy maybe helpful for some. This is not the complete picture just a simple overview and does not go into the detail of exercise metabolism byproducts.

All running or walking burns for energy at the same time fat, carbohydrate and protein. You are always burning for muscular energy or as part of your general metabolism all three fuels. The level of effort changes the ratios and maximum amount utilized for energy production of these three fuels. Your personal genetic makeup, nutritional state, fitness level and other factors influence the limits of the absolute amounts and ratios, the utilization of muscles deriving energy from these three energy-producing fuels.

You need to think about these three muscle fuels in four different ways. One, that these three fuels are stored in the muscles as quick ready energy. Two, that the rest of your body has an energy supple of these three fuels that can feed your muscles. Three, that you can also eat while running these three fuels; namely carbohydrates, fats and proteins. There by resupplying the body and muscles of these fuels. Four that these three fuels are also part of the body's structure and basic energy needs apart and separate from muscle energy needs and need to be supplied by eating. This becomes more important as time goes by in an event.

When you are fresh, rested and well nourished and start to run, your muscles and body are full of stored fat, carbohydrate and protein. In this fresh state beginning at a slow pace you burn fat as the main fuel source followed by carbohydrate and a very small amount of protein. Remember you are burning all three at the same time, it is just the ratio and total amounts that change. Because you are running slowly the total amount of energy used is low so you are not burning that much fat, an even lower amount of carbohydrate and a very small amount of protein. As you increase your pace you burn a larger amount of your muscle stored fuels in a givin time and burn an increasing amount of your stored carbohydrate relative to fat. When your muscles are rested and both carbohydrate and fat replete. The harder your effort the greater the percentage of muscle carbohydrate is used for energy compared to fat. This duality is an important point to remember. The amount of protein burned for energy as you increase your pace can vary greatly depending on pace, training state, nutritional state and your personnal genetic make up. The burning of protein for fuel is all most always both a minor percentage of the total energy produced and a minor percentage of the ratio to the other fuels (fat, carbohydrate) at any pace. Although protein is an important consideration in thinking about how the body derives muscular energy and replaces body structure. Certainly what protein to eat during a long ultra event gains importance as an event grows in time. It is of a less immediate nutritional concern compared to carbohydrates an fats, when thinking about protein as an muscle energy source. The main thing you don't want to do is deplete your muscles completely of carbohydrate as this is the main driving force to increase the use of protein as an muscle energy source and in so doing promote muscles breakdown to derive the protein to use as fuel (stupid to do). You want to build your muscles up in training and limit break down as much as you can in racing. I will now focus my discussion mainly on carbohydrates and fats.

As you increase your pace from a fresh state you reach a maximum steady state endurance pace. You will be breathing hard and are now burning the near maximum rate of muscle stored fuels in a given time and this maximum steady state pace will burn a high ratio of stored carbohydrates to fat. So you will be burning less fat relative to carbohydrate. But you are also burning a large total amount of energy in a given time so you are still burning a larger amount of fat compared to rest or a very slow pace. Remember that carbohydrate use verses fat use is a ratio based on effort level and the fat and carbohydrate level in the working muscles. When you exercise at the most extremely hard pace, carbohydrate use goes dramatically up in relationship to fat. You can use up most of the muscles stored carbohydrate in a 10 k race with a really hard effort. As time goes on you use up your carbohydrates that are stored in your muscles. When this muscle stored carbohydrate is depleted your pace slows. Hitting the wall in a marathon is usually associated with this reduction of stored carbohydrate and happens often for people at around 17 to 20-mile mark of the marathon.

The advantage of burning more carbohydrates and less fat are that burning carbohydrate for energy produce a slightly greater amount of energy for a given amount of oxygen used compared to fat. So at your maximum rate of oxygen delivery to the muscles if your muscles are replete with carbohydrate you can produce more energy output if the carbohydrate in your muscles are not used up and you are running hard enough to be using a high rate of carbohydrate. But you only have a limited time that you can burn a high rate of carbohydrate, because once your high level of stored muscle carbohydrate is lowered by exercise in an event you can never get back to the high level during that same event (normal events). This next point is very important to remember and over looked often in a discussion about muscle energy and diet during exercise. Having carbohydrates in your muscles enables you to burn a larger amount of fat in a given time. So if you are carbohydrate depleted you do not burn fat as efficiently and the total amount of energy you can produce falls dramatically. So when you hit the wall you can still have plenty of fat in your muscles but can't run well and feel energy depleted. It is generally because of the low level of muscle carbohydrate and the inability to use fat effectively as a fuel source that makes you go so slowly and feel so energy depleted. Unfit athletes hit the wall much harder than fit athletes, because of the unfit athletes poorer ability to use fat as a muscle energy source and an accelerated usage and depletion of carbohydrate.

You also use up the stored fat that is in the muscle along with the stored carbohydrate so you can also deplete your muscle of fat not just carbohydrate. How long it takes to deplete both the carbohydrate and fat from muscle during exercise depends on muscle fiber type, training state, nutritional state, pace, environment and god knows what else. This brings me back to my original point two and three. While we workout and deplete our muscles of fuel substrate namely fats, carbohydrate and some protein. The body is turning on the mechanisms to refuel the muscles of these three substrates as we deplete them. From both body stores and from the food in our stomachs. So we are always in a state of flux, on one hand depleting these muscle stored fuel substrates for energy, this rate is increased greatly through exercise and level of intensity. Then replenishing muscle fuel substrates, the rate also increased by exercise, depletion level and fuel substrate availability. Proper pacing lessens the rate of carbohydrate use and slowly depletes your muscle carbohydrates down to the point where the body stores and ingested carbohydrates can maintain a status quo equilibrium of muscle carbohydrate use versus muscle carbohydrate resynthesis. We can greatly enhance the replenishment of muscle fuels for energy (all three but especially carbohydrate), over relying on body stored fuels alone, by eating during exercise. The science and art of sports foods is founded on this principle.

When we train for endurance we alter the muscles to use fat as an energy fuel in a very efficient way. We can burn a larger amount of fat in a given time period at a given exercise intensity and a larger amount of fat compared to carbohydrate at a given exercise intensity. This conserves muscle carbohydrate. There is also an increase of capacity to bring fuel into the muscles and an increase of the total amount of stored carbohydrate and fat in the muscle when fresh. This altered fuel usage is in part what enables a fit athlete to perform at a high level of energy output for a long time period. It is obvious that training makes us run longer, farther, faster and more comfortably while doing so. But fit of unfit you need your muscles to have carbohydrate in them to enable the muscle to burn fat efficiently, help protect muscle protein structure from breakdown and minimize the rate protein fuels muscles and feel your best.

What is not as obvious is how eating during long runs effects our energy levels and performance. All food we eat are more than just fuel substrates and as an event grows in time what we eat has an ever growing importance beyond just being a fuel and an increasing role in replacing our physical structure. Events lasting over half a day this replacement of structure starts becomes very important. This is one reason why it is relatively easy to eat for a 50 miler or less and much harder for a 100 miler or more.

In order of importance are water, carbohydrates, fats and lastly proteins. I put water first because we start to dehydrate as soon as we start to run and just a few percentage of weight loss through dehydration degrades performance and this can happen before we have depleted our muscle energy stores. The only extra water in the body is what is in the stomach. So we need to rehydrated right away and keep some water in our stomach all the time when we workout.

Carbohydrates are next because it takes only a few hours of intense exercise to deplete muscles and liver of stored carbohydrate. So we need to ingest carbohydrates soon after starting exercise to feed the muscles and keep a high rate of ingestion for the entire event. Ingesting carbohydrates as some form of glucose we quickly and readily refuel carbohydrate depleted muscles. The more depleted the muscles are the more the muscle turns on the mechanisms to transport glucose from the blood to the muscle. Very large continuos amounts of ingested glucose during endurance exercise enhance performance more than any other food. If you can follow what I have written it is clear why this is so and has been proven time and again experimentally.

Fats and lastly proteins become more important as an event becomes very long. We have a large store of fat in our bodies (most of us, especially me!) but a more limited storage of fat in the muscles. Eating some fat during long events helps increase the fat usage of the body and muscles. This ingested fat helps fuel fat depleted muscles more effectively than depending on non muscle stored body fat alone. You can really feel the beneficial effects of eating fat, especially after running all day and half the night when you get run down and cold, the thermogenic effects of eating fat are so immediate and dramatic. There are a number of body structure concerns involved with eating fat during very long runs that are positive.

Remember if your very fit you use muscle and body fat more effectively for energy, use muscle carbohydrate more efficiently at normal endurance running pace. Store more carbohydrate and fat in your muscles when rested before an event even begins. Transport a larger amount of fat and glucose from the blood into the muscle when running.

So the bottom line is train hard for a long time to make your body use fat effectively and conserve carbohydrate (That's one reason why good runners are thin, they use fat very effectively as a energy source not just in their muscles alone but their liver as well). Know what your potential is and pace intelligently from the start of an event. Eat correctly from the start of an event. That would be, drink enough water to maintain hydration. Ingest large amounts (like 100-125 grams an hour if possible) of some form of glucose. A small amount of fat and protein should be beneficial between 3 or 4 hours up to about 12 hours. Then as the event become longer in time, about 12 hours, a much larger increase of fats and proteins should be uses along with the high carbohydrate usage. Vitamin and mineral usage should mirror fat and protein usage. The increase in fat and protein use becomes increasingly very important if the total time of the event gets to be really long over about 16 hours, running into multi day events. The replacement of the body's structure mirrors the time frame of fat and protein needs in importance. This replacement of structure as well as energy replacement needs to be addressed very early in long events, for optimal efforts in long events. Deciding pacing effort in long events, the resultant balance and ratios of fuel substrates used, the replenishment of these fuel substrates and replacement of body structure through eating, is no small task. Hopefully this is of some help in that task

One reason the run walk pacing strategy works well, is the slowing of pace allows carbohydrate recovery to happen. When you alter your stride your using a different muscle firing pattern and working at a lessened effort. This enables you to use some less fatigued and fatigued muscle in a low effort way. Because your still walking and not sitting you still have good circulation of the muscles. This helps bring blood and fuel to the muscles. Carbohydrate recovery in muscles can be very fast from muscles with very low carbohydrate levels, bringing up the level to just low muscle levels, this recovery of muscle carbohydrate can be especially fast if you have ingested a large amount of carbohydrate, this raises your blood sugar level up. Allowing the quickest possible muscle carbohydrate recovery. Low blood sugar levels equals slow recovery time, high blood sugar levels equals faster recovery time.