FAT a burning question for the long distance runner

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Racing in any running race requires a specific and targeted approach to your objective. The objective can be a one day race of a short distance, a medium distance race such as a marathon or maybe you are going to run long, 50 miles or more… You may even be running for multiple days?

The important thing to remember is that ‘training’ and ‘racing’ are 2 separate things and your fuelling approach should reflect this.

Any long distance event will require you (a unique individual) to utilise fat as a fuel source. You can teach your body to utilise a greater amount of fat as fuel and also to use less calories overall, making you more economical.

Other factors come into play, for example, someone who will be in the top 5% of the race results will have different needs to a runner in the final 5%. However, fat as a fuel is used and we can all adapt.

If you follow the guidance below over a 12-16 week training period you will adapt to fat usage.

Run at the correct intensity -slow and steady. Find out a specific heart rate zone in which to work. Maffetone method is a good starting place.

Avoid fluctuations in intensity when training long, average heart rate or power output are NOT the critical figures, it’s TIME IN ZONE that counts.

Eat foods which are balanced with low GI (glycemic index) carbohydrates and fats to encourage fat usage and avoid sugar spikes.

Avoid gels and sugar products based on point 3 above.

What happens during the race?

Let’s assume that while racing you burn 700kcal per hour, 50% of which comes from carbohydrate and 50% of which comes from fat. Carbohydrate loss is the one to worry about, in this scenario, 350cals (50% of 700). 350kcal of carbohydrate equates to 88 grams of carbohydrate (4 kcal per gram).

Here’s the big problem!

Most individuals can only absorb approximately 60g+/- of carbohydrate per hour.

A simple way to look at this is by looking at ‘you’ as a car ferry. The cars that you will fit in the ferry boat carry carbohydrate, lets say 10g per car. Your car ferry only holds so many cars… in our scenario it is 6!

But we have already worked out that you as an individual burning 50/50 carb and fat require 88g of carb. That is 8.8 cars.

So, you line up 9 cars on the dock every hour but only 6 fit. This leaves 3 on the dock. The boat sails away, comes back 1-hour later and 9 new cars have arrived in addition to the 3 you left waiting…

This is the same as adding carbs through your intestine wall to your blood stream. If you carry on missing 2.8 cars every hour, one thing is guaranteed to happen – you will either need to slow down or you will blow up!

As stated, a typical person can absorb 60gram +/- per hour.

For our example above, that means that you’re going to fall short. You’re using 88 grams per hour and you can only replace 60 grams per hour. That’s a 28 gram / 112 kcal per hour deficit.

If you try to eat more (an additional 2.8 cars) every hour, it’s unlikely to be digested and will simply sit in your stomach or intestines without providing energy. That may be okay for 1-hour, possibly 2 but then the classic scenario of stomach distress happens. How many runners have you talked to that have complained of stomach distress while running?

It’s really important that you understand, eating more food doesn’t mean you’ll have more energy and it may well mean that you’ll face stomach upsets.

Our above scenario works on the presumption that you are only using 700kcal per hour, bigger people and less efficient people may be using more? Our scenario also assumes that 50% is coming from fat and 50% fro carb – that may not be the case at all! In-fact, as much as 80-100% of energy may be coming from carbohydrate! A disaster for the endurance athlete.

Take multi-day racing for example when you are racing day-after-day with compromised recovery and limited calories. You just simply cannot carry enough carbohydrates to sustain you over the period of an event, particularly if it is a self-sufficient event such as the Marathon des Sables.

To move forward effectively armed with good knowledge about you as a person, you need to address 3 questions:

How many calories do I burn per hour?

How many of those calories come from fat and carbohydrate?

How many calories and what percentage of fat/ carb should I be taking in as a consequence?

Do a 1 hour run at your ‘race pace’ and then use your heart rate monitor to calculate how many calories per hour you are using when exercising at that intensity. These figures can be somewhat unpredictable but it will provide a starting point from which to work from.

Most heart rate monitors will use your age and weight to work out kcal per hour. This will only give you an approximate calorie burn per hour and won’t tell you what % of energy comes from carb/ fat. There are some tools on the internet such as: http://www.braydenwm.com/calburn.htm which can help to give you a basic idea.

Working scenario:

Billy is 43, weighs 82 kg and is racing a 100 mile race, he falls into a category of 65 carb /35 fat fuel usage. Billy has one main objective – to complete the event without major disaster and to run as much as possible. Billy running at his proposed race pace will use 820 Kcal per hour, so the calculation works like this:

65/35

Fat contribution:  820 Kcal x 35% = 287 Kcal

Carbohydrate contribution: 820 Kcal x 65% = 533 Kcal

Calories from fat do not need to be replaced – we all have plenty of stores. However, carbohydrate NEEDS replenishing and the body can only hold so much. 1g of carb is 4kcal. So, Billy will require 133g per hour!

Uh oh! We have already clearly said that around 60g of carb per hour is all that we can take. Billy is in trouble… he is missing out on 73g per hour. Remember the car ferry and the cars sitting on the dock waiting to get on the boat – Billy, racing over 100-miles will need a multi-story car park for the cars that won’t fit on his boat.

Although Billy is a ’sample’ case, this scenario happens time and time again in races all over the world.

How do you solve this problem?

Billy needs to utilise fat as a fuel more and be less reliant on carb.

The body is pretty clever. It is able to switch its metabolism. So, in the case of Billy, the availability of carbohydrate is becoming an issue, as a result the body will start to utilise fat stores. This is a good thing. Yes? Well yes but one thing will have to happen – Billy will need to slow down. Now for many of us, that is not an issue as a finish is a primary goal. However, this can be hard to take and yes, you may well feel lousy. More importantly, pre-race objectives may go out of the window… target times will be lost and a possible top-10 (if that was an objective) will also go out of the window.

Let’s cut to the chase

If more of your energy comes from fat, you’re less likely to run out of carbohydrate. The best athletes in the world require energy (Kcal) to run at race speed. If a large chunk of that energy requirement comes from fat, their total carbohydrate use is reduced.

As an example, by making changes to Billy’s training and diet, the new version arrives for the 100-mile race using only 700Kcal per hour and 55% of energy is being provided by fat.

A quick maths calculation reveals the following:

1. He’s using 315 Kcal of carbohydrate per hour on the run, compared to the previous figure of 533

2. With his intake of 60 grams per hour (240 Kcal), he now only has a deficit of 75 Kcal per hour compared previously with 292 Kcal (73 grams)

3. As a consequence, Billy could run the whole 100-mile race with a smile.

In conclusion:

For you to run an ultra feeling comfortable, relaxed, efficient and on target, you need to go away and find out:

How many calories do you burn per hour?

How many of those calories come from fat and carbohydrate?

How many calories and what percentage of fat/ carb should I be taking in as a consequence?

You may well find that you need some specific help in working out some of the data and figures outlined above.

A Metabolic Rate Test HERE and a Metabolic Test is the way forward HERE.

In training (not all training, just the slow/ steady runs):

To recap earlier points:

Run at the correct intensity – slow and steady. Find out a specific heart rate zone in which to work. Maffetone method is a good starting place.

Avoid fluctuations in intensity, average heart rate or power output are NOT the critical figures, it’s TIME IN ZONE that counts.

Eat foods which are balanced with low GI (glycymic index) carbohydrates and fats to encourage fat usage and avoid sugar spikes.

Avoid gels and sugar products.

Finally, daily diet plays a key role in overall adaptation. Simple sugars, processed food and so on are all bad in day-to-day life for an endurance athlete. Keep them at a minimum and as a treat.

Periodise your eating just as you would training.

Think about dietary fat and fat-burning and think low carb.

A low carb and high fat (LCHF) diet forces ones body to burn fat. As you will now know, fat stores are pretty much unlimited even in the skinniest guy or girl. Optimising ones body to use fat will use less carbs and allow you to perform longer. This becomes even more relevant in long endurance events, especially when the pace is slower and the energy requirement to run at a certain pace is lower.

Notice I say low carb and not no carb! Carb has a place in your diet, it just needs to be consumed at the correct times and make sure the carbs you eat are low GI and good quality. Avoid white pasta, white bread, anything refined and potatoes for example (high GI) and eat sweet potato, beans, whole grains (but be careful) and plenty of vegetables (low GI).

Protein is also key for recovery, muscle growth and repair.

A typical runners diet, broken down into percentages of fat, protein and carb would have often (and in many cases still does) look like this:

Carb 60%

Protein 15%

Fat 25%

The modern day ultra, endurance or multistage runner has percentages that look like this:

Fat 50%

Protein 30%

Carb 20%

Of course, we have all been told that high fat is bad for us but sugar and in particular, refined sugar is the real evil and in day-to-day life it just doesn’t help you as an ultra runner.

Note though, fat should be good quality – oily fish, nuts, seeds, good quality meat, olive oil and so on. Bad fats are the obvious ones such as crisps etc.

Periodise your food intake

Just like you will plan training – intervals, hills, long runs and so on. Food should also be planned in-line with training and racing needs. I will write more on this in another post.

In simple terms:

Train fasted for long runs and keep your pace low to promote fat burning. Actually eating fat before a long run has benefits in helping and promoting fat burn. As does coffee. Try Bulletproof coffee before long and slow runs, read here

Recovery consume a little good quality carbohydrate post training, ideally within a window of 30 to 40-minutes and include good quality lean proteins.

Racing

When racing a long distance race, you as a runner will be far more efficient at using the calories that you have within your body if you follow the guidelines above. We have already said that the body can only hold so much carbohydrate, so, if you have your fat burning turned on you will go longer. Your food requirements whilst racing will also change and you will require less sugary products to keep you going.

Pace (the speed you run) will also impact on how the carb/ fat ratio is used. Runners who are racing (looking for a top placing) incorporate different methods to perform. Often called, ‘train low and race high’ – Timothy Olson for example is a good example. Timothy eats high-fat and low carb in training and day-to-day life but when he races he uses sugar (such as gels) to fuel him during the run. His training has adapted him to use less gels (he uses more fat as fuel), last longer and each sugar smack he gets while racing has less work to do as his carb stores are always being used in conjunction with fat.

Carb loading has been used for years and it’s often misunderstood. How many times have you seen or heard a runner gorging on carb for days before a race – why? We already know that our body can hold so much stored carb (approx 2500 cal) so, when we ‘carb load’ we are basically making sure that our carb stores are full pre a race. Don’t over indulge. It will just sit in your stomach, cause discomfort and make you feel lethargic and more than likely, you will add weight to your frame. As a guide in the 24-hour period before your race, keep a balanced diet but up the carb % say from 20 to 35/40%. Again, make this good carb – low GI.

What is key here is finding what works for you.

“The benefits of low carbs really start to distinguish themselves when you get beyond the marathon, because you’re definitely running out of carbs then,” – Jeff Volek

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Always check with a medical professional before making any drastic change to your eating  or training regime. The information provided in this post is designed to make you question and pursue an opportunity to enhance your training and racing and we stress that you must find out what personally works for you.

Thanks to Marc Laithwaite for his contribution to this post.

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6 thoughts on “FAT a burning question for the long distance runner

  1. I always read these articles with interest, but none of them seem to answer the question that I have about fat-adaptation, so here goes………
    What changes at the cellular level occur when you are ‘fat-adapted’? And following on, what scientific proof of it is there?
    As I understand it fats get broken down by enzymes through various pathways producing ATP, which is used as the energy source.
    Does fat-adaptation involve changes in the level of these enzymes, or maybe the efficiency of transporting fat into cells & mitochodria is increased, who knows? What evidence is out there?

    As a side note Koop advises you to “forget fat-adaption”, but what does he know?

    Jules

  2. I tried Maffetone for three months last year, I found it just slowed my pace right down and I gained a lot of weight. Question is – can I do intervals and fartlek during the week and do my 80% slow runs at weekend for learning to fat burn?

  3. Pingback: Ultra marathon Daily News, Fri, Oct 21 - Ultramarathon News, Podcasts, and Product Reviews

  4. Pingback: Other people’s words – Bar-barella

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