Archives for category: Sports Nutrition

Introduction

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Hello,
My name is Kevin Beasley and I’m a performance nutritionist. I have worked with inter-county Gaelic football teams (male and female) at both senior and underage levels for the past eight years. I also have vast experience of working with clients from a variety of different sports.
If you are someone who enjoys working out but can’t get to the gym now because of the current lock-down, you may be fretting over your nutrition. You may be unsure over what you should be eating due to reduced training intensity or frequency. However, there are some easy steps you can take to remain in good shape, maintain a good body composition and most importantly remain healthy.

Calorie Intake

Before we start on the nitty-gritty, we will take a moment to discuss calories and calorie balance. One of the reasons we eat food is to fuel all our bodies activities throughout the day. These calories provide energy for our metabolism, helps our bodies to digest and process food, and help us to carry out all the activities we do throughout the day.
In order to maintain our current weight, we need to eat the same number of calories that we’ve burned over a 24 hour period. If you eat 2500 calories in a day and you also burn 2500 calories then you should maintain your weight. If you eat less calories (e.g. 2000 calories – calorie deficit), you will lose weight. If you eat more calories (e.g. 3000 calories – calorie surplus), then you will gain weight.

energy-balance-diagram

(Image courtesy of First Rate Fitness)

This weight loss or gain can come from many different compartments in out body. These can include:

  1. Body fat
  2. Muscle
  3. Water
  4. Bone
  5. Muscle and liver fuel stores

We normally don’t eat the exact number of calories we need every day. Sometimes we can eat more, sometimes we can eat less. These figures normally balance out over several days. We have inbuilt systems in our body that ensure we compensate if we under eat over eat calories on a given day.

Daily Energy Requirement Calculators

If you would like to calculate how many calories you need to eat on a given day to maintain calorie balance, there are lots of different online calorie calculators available online.
One of the easiest ones to use can be found here .
This calculator will give you an estimate of how many calories you need to eat in order to maintain your weight based on your age, gender, height, weight and activity levels. Whatever number is calculated is just an estimate.

Use this number as a starting point and based on your weight fluctuation over a 7 day period, you can adjust your calorie intake up or down depending on your body composition goals. Add more calories if you want to gain weight, remove calories if you want to lose weight.

Avoid Large Calorie deficits

If you decide that you want to lose body fat over the next several months, I will issue a word of caution. Having a large calorie deficit for a prolonged period of time can lead to:

• Weight loss – either muscle mass, fat mass or a combination of both
• Reduction in your metabolism – this may lead to yo-yo weight loss and weight gain
• Lowered immunity – making your body more susceptible to infections
• Lowered hormone levels</p>
These effects are not desirable, from a performance and a health perspective. It’s normally recommended to keep your calorie deficit within 20% of your maintenance calories.

Example: if your recommended calorie intake to maintain weight is 2000 calories, then you shouldn’t eat less than 1600 calories per day (80% of maintenance calories – 20% deficit) if you’re trying to lose weight.

A good rule of thumb is to try and lose weight while eating as much food as possible.

Food Diary

While it’s not necessary, some people like to record their food intake in order to balance their calorie intake. A free app that many people use is called MyFitnessPal. You can download this app for free. This app will give you accurate measures of how many grams of carbohydrate, fat and protein, as well as calorie, vitamin and mineral intake for a given day. However, you will have to pay for some of the more advanced features on this app.
More simpler measures include writing down your food intake for a given day on a notebook. Other people like to take photos on their phone. Choose whatever method fits with your temperament and lifestyle. The goal is to have a record of what you eat in a given week so that you can make adjustments for subsequent weeks based on whether you’ve achieved your body composition goals or not.

Weekly Weigh-in

It is advisable to weigh in once per week to track changes in weight. The best time to weigh yourself is first thing in the morning after going to the bathroom and before eating breakfast. Weigh yourself on the same day and at the same time every week. Friday morning is generally the best day to weigh-in.

Macro-Nutrients

Macro-nutrients are the nutrients that we need to eat in large quantities. In the following sections I will go through the three main macro-nutrients, their functions and the types of foods we find them in.

Protein

Protein is a very important nutrient and protein supplements have increased in popularity over the last 10 years. Protein is very important from a sports perspective – it helps to build and repair muscle after a training session, helping to make us stronger and reduce risk of injury. It also plays an important role in strengthening our immune system.

We can get protein from many common foods. The table below gives you examples.

ANIMAL SOURCES OF PROTEIN PLANT SOURCES OF PROTEIN
Fresh and tinned fish Tofu
Lean red meat Tempeh
Poultry (chicken & turkey) Chickpeas
Dairy including high-protein versions (milk, yogurt) Quorn/Mycoprotein
Eggs (egg white is protein source) Lentils
Whey protein supplement Quinoa
Whole nuts and seeds

You should eat a portion of protein with breakfast, lunch and dinner everyday (regardless of whether you’re training or not) and include extra protein snacks on resistance training days. One of the benefits of protein is that you can over-consume protein and it will not lead to increased body fat. Over-consumption of carbohydrate and fat can lead to an increase in body fat.

The recommendations for protein intake is between 1.5 – 2g/kg BM/day (read as 1.5 – 2 grams per kg of body mass per day).

Taking an 80 kg person as an example, protein intake would equate to:

80 x 1.5 = 120

80 x 2 = 160

Therefore, an 80 kg person should be eating between 120 and 160 g protein per day.

Carbohydrates

Our bodies use carbohydrate for energy, especially when we are moving at a higher intensity like when completing a training session. Healthier carbohydrates also contain fibre which is great for our digestive system health.

We have a fixed capacity for carbohydrate storage in our bodies. The average person can store approximately 450 g of carbohydrate in their muscles and liver. High intensity exercise will deplete these carbohydrate stores, so it’s important to re-fill these stores before our next training session. When choosing your carbohydrates, try and choose “natural” over “processed” carbohydrates.

EXAMPLES OF NATURAL CARBOHYDRATES EXAMPLES OF PROCESSED CARBOHYDRATES
Whole fruits Breakfast cereals
Grains (brown rice, brown pasta, quinoa, cous-cous, oats) Fruit juices
Root vegetables (potatoes, sweet potatoes) Biscuits
Legumes (beans, lentils) Cakes
Brown bread Desserts
Chocolate
Soft drinks

As a rule of thumb, natural carbohydrates contain more nutrients, more fibre and give a more sustained release of energy compared to processed carbohydrates. Processed carbohydrates usually have less fibre and also contain ingredients that may be less beneficial for our bodies (e.g. salt, sugar, artificial colouring’s and flavouring’s).

I am not telling you to never eat processed carbohydrates, just to consume less of them. View them as occasional treats rather than as a part of your everyday diet.

The recommendations for daily carbohydrate intake are based on your activity levels. Given the current situation we are in, the recommendations below will be suitable for most peoples activity levels.

ACTIVITY LEVELS RECOMMENDED CARBOHYDRATE INTAKE

(g/kg BM/day)

Low Intensity or Skill based activities 3 – 5
Moderate exercise program (approx. 1 hour per day) 5 – 7
1 – 3 hours per day or moderate to high-intensity exercise 6 – 10

The amount you eat depends on the duration and intensity of a session. The harder and/or more intense the training session, the greater the intake.

I would recommend eating a carbohydrate containing meal approximately 3 hours before commencing your training session and eating another meal within two hours of finishing to promote recovery and re-fueling.

If your training session lasts longer than 1 hour I would also advise drinking 30 g carbohydrate per hour (500 ml bottle of sports drink contains 30 g carbohydrate).

Fat

Fat is the most misunderstood nutrient. It has gained a lot of bad publicity over several decades, being implicated in heart disease and high cholesterol levels. However, this in part can be blamed on processed foods which contain unhealthy combinations of sugar, salt and fat. If we get our fat from natural sources, it is very beneficial to our health and performance.

Fat is used to repair cell walls, make hormones, dampen inflammation, provide the fat soluble vitamins A, D, E and K, as well as essential fatty acids (omega-3 and omega-6). We generally only need to consume small amounts of fats with our meals to hit the recommended amounts.

HEALTHY SOURCES OF FAT
Extra virgin olive oil, rapeseed oil
Milk, cheese, yogurt
Fatty fish such as salmon, tuna, mackerel and herring
Whole nuts and seeds
Avocados
Eggs
Dark chocolate

The recommended intake of fat is 1g/kg BM/day.

Conclusion

OK, that’s a lot of information to take in. What can you do to get started? Well, if you don’t want to measure out and weigh your food, here are some simple guidelines to follow:

Non-Training Day

  • Eat a minimum of a palm full of protein with breakfast, lunch and dinner every day.
  • Eat moderate amounts of healthy carbohydrates with breakfast, lunch and dinner every day.
  • Where possible, add in small amounts of healthy fats (e.g. adding nuts or seeds to your morning porridge).
  • Add in vegetables where possible (e.g. onions, spinach, carrots, broccoli etc)

Training Day

  • Add in larger portions of carbohydrates to your meals to fuel-up before training  and re-fuel afterwards.
  • Add in some extra protein containing snacks to help with muscle building and repair.

Please check in next week as I will be posting another blog on sports nutrition.

If you have any questions, please email me at: kevin@metabolise.ie

Check out my website and my YouTube channel which I update regularly with cooking demonstrations and recipes. I also have videos from Kerry footballing greats discussing the importance of sports nutrition.

Subscribe to my YouTube channel and get a notification every time I post a new video.

Finally, check out my blog for further posts on sports nutrition related topics.

Stay safe everyone, wash your hands regularly and practice physical distancing!

Kevin

Hi there,

Training and competing pose challenges on the body with regards fuel stores, hydration and regulating body temperature. With a few exceptions, very few sports events put as much stress on the body as competing in a marathon. Here are some tips that will help you prepare and recover for your upcoming marathon.

Week Before

1- Rest and Sleep

While not necessarily a nutrition tip, it is vital to rest and sleep well in the week before your event. You have all the hard training done, although you might have a few light sessions planned. Getting at least 8 hours sleep every night will allow your body to recover and be fully prepared for the task ahead.

2- Carb Loading

We have two fuel sources that our body uses during exercise – fat and carbohydrate. At lower exercise intensities (resting, walking, jogging), our bodies prefer to use fat as we have large quantities stored in our bodies.

At higher exercise intensities (hard running), our bodies prefer to use carbohydrate stored in our muscles and liver as it can access it and release the energy more quickly. However, a problem with this is that we have the ability to store only small amounts of carbohydrate in our bodies (300-500g). If you’re trying to perform a personal best (i.e. exercising at a high intensity), there is a possibility of running out of carbohydrate (i.e. hitting the wall, bonking) later in the race. When this happens you will have to slow down, and you might feel dizzy, faint or disorientated.

In order to prevent this happening, you will have to carb-load. Carb-loading involves eating larger than normal amounts of carbohydrate in our to max out our bodies ability to store carbohydrate. This should allow you to run faster for longer.

The recommendations say that you should be eating between 8-12g per kg of body weight. As an example, for a 70kg person, this would mean eating between 560 – 840g of carbohydrate. This is very difficult to do eating a healthy diet.

In order to achieve this, you will need to cut back on eating protein, vegetables, fat and fibrous starchy carbohydrates (e.g. porridge oats, brown pasta and rice). Normally it is a beneficial to eat these types of foods, but they may stifle your appetite when carb-loading, making it more difficult to reach your carbohydrate targets.

You will need to eat more sugary types of carbohydrates (e.g. sugary breakfast cereals, fruit juices, jam, snack bars, sports drinks, smoothies, white flour based foods (pancakes)) and low fibre starches (e.g. white rice, white pasta, white bread).

Eating these types of foods allow you to over-eat and hit your targets. A word of warning – only do this when preparing for a marathon, when doing a long run (18+ miles) or practicing your race nutrition. If you do this on a regular basis, it will more than likely lead to you increasing your body fat.

Finally, I would recommend doing this 2 days before your race, giving your body time to digest and store carbohydrates and get rid of waste. You can then eat a normal diet the day before.

3- Hydration

When your body stores carbohydrates, it does so with water. If you’re eating and storing larger than normal amounts of carbohydrates, you are drawing extra water into your muscle and liver. As a result, you may need to increase your fluid intake. Keep a close eye on your hydration levels.

  • Thirst may increase.
  • Urine may be darker in colour.
  • You may only pass a small amount of urine.

If you experience any of these symptoms then drink a pint on water immediately and then drink 200ml every 20-30 mins until the symptoms above are improved. It is also best to drink with a meal or snack as your body will absorb fluid more efficiently.

Morning of and During Race

4- Breakfast

Marathons normally start early in the morning. Try and eat a breakfast 2-3 hours before the race start. This is highly individual but ensure you get some carbohydrates (e.g. porridge) and a small amount of protein (e.g. boiled egg) at a minimum. Continue hydrating (but not too much).

5- Eating during race

After the first hour of your race, you should be aiming to consume 30-60g carbohydrate per hour during the race to keep your blood sugar levels high, continuing to fuel your run. A typical sports gel will contain 30g of carbohydrate. So will 500ml of a typical sports drink. However, consuming these in large quantities can cause stomach ache, pain and diarrhea in some people. It would be a good idea to vary carbohydrate sources (e.g. ripe banana, energy bar, snack bars) to prevent these uncomfortable side effects.

6-  Hydration

How much you sweat during a race will determine how much fluid you drink. The environmental conditions and the course will play a role in this. You will sweat more in warm, humid condition and/or on a hilly course. Conversely, you will sweat less on a cold, windy, rainy day and/or a flatter course. Some level of dehydration is OK and may be beneficial as you will be lighter and will expend slightly less energy. This is typically up to 2% of body weight. Anything over this may impair performance. It is very difficult to give a recommendation of how much fluid you should drink, As well as the factors listed above, everyone has slightly different sweat rates. At a rough estimate, you should be drinking 400-500ml per hour.

Be careful of drinking too much fluids, as this could mean an early finish to your day!

After Race

7- Immediately after race

Within 0-60 mins of your race finish, you should try to consume a recovery shake containing carbohydrate and protein or if not available, 1-2 bottles of sports drinks. This will help to kick-start refuelling.

8- 1-3 hours after race

You should aim to eat a big meal 1-3 hours after a race. This should contain a large portion of carbohydrates, protein and vegetables. The carbohydrates will continue to refuel the body, protein will help to repair and rebuild muscle and vegetables will contain vitamins and minerals which will help your immune system.

9- 72 hours after race

Continue to eat breakfasts, lunches and dinners containing protein, carbohydrate and vegetables up to 72 hours after the race. One of the big complaints by novice marathon runners is DOMS (Delayed Onset Muscle Soreness). DOMS is muscle soreness which appears two days after the race. By eating regular doses of protein with your meals, this will help with repairing muscle and help to prevent DOMS or at a minimum diminish the muscle soreness.

10- Rehydration

If you have a portable scales then bring it with you to the race. Try and weight yourself immediately before and immediately after the race. You should have lost weight – if you have gained weight then this means you drank too much fluid.

If you lost weight, get the difference and multiply by 1.5. For example, if you lost 3kg then the amount of fluid you need to drink to fully re-hydrate is 4.5L (3 x 1.5). You don’t need to drink all of this immediately, but over the 24 hours after the race.

Word of warning – beer and alcohol don’t count towards rehydration. Drinking large quantities after a race will cause further dehydration and will delay recovery.

I would like to wish you all the best in your upcoming marathon. If you follow the steps above I think you will have an enjoyable race and hopefully hit a P.B.. If you have any questions, please email me at: kevin@metabolise.ie

Yours in sport,

Kevin

D.I.Y. Energy Drinks for Triathlon

The two best ways to increase your carbohydrate intake are through fluids and food. Fluids have the advantage of hydrating you as well as providing energy. Many sports drinks and water soluble powders are commercially available which are ready off the shelf. However, I prefer to make my own drinks for the following reasons:

  • I can control the amount of carbohydrate, the taste and adjust to my preferences
  • It’s cheaper to make your own.

If you decide to make your own sports drink, you will need to buy maltodextrin or glucose powder and fructose powder. You can buy 1kg packets of maltodextrin (approx. €5) and fructose (approx. €8) online. This will be enough to last you several weeks.

To prepare your own sports drink, you will need the following ingredients:

  • 50g Maltodextrin
  • 25g Fructose
  • 1L water
  • 1g table salt
  • Flavouring – Miwadi/Robinsons

It is important to use the measurements outlined as this is the optimal blend. Too much maltodextrin/fructose may cause discomfort such as bloating, cramping and diarrhoea. Too little carbohydrate and you won’t be delivering the carbohydrate at the optimum rate. The combination of fructose and maltodextrin allows the maximal rate of absorption of carbohydrate compared to using either on its own. Another added benefit is that the addition of fructose allows greater water absorption, promoting greater hydration. Adding a small amount of salt is also important as the sodium in the salt allows greater absorption of water in the intestine.

Sports gels are another great way of increasing your carbohydrate intake during the cycle (and run leg) as they are small and easy to carry. As with sports drinks, you should be looking at the different types of carbohydrate contained in the gels. In general, fructose in combination with glucose, maltodextrin or galactose will allow the maximum rate of delivery of carbohydrate to your working muscles. The optimum ratio is two parts maltodextrin,glucose or galactose to one part fructose.

Not to be under-estimated is taste. When out on a long ride, I find that I look forward to eating my gels/bars as a treat. However, many gels are tasteless. I find that eating gels with a pleasant taste gives me an extra psychological lift! One brand that I can recommend is the TORQ brand of gels, which are very tasty and come in a variety of flavours. If sports drinks and gels are beyond your budget, foods such as ripe bananas, figs and raisins are also high in carbohydrate and might be a low cost alternative.

 

The maximal rate of which your body can absorb and use carbohydrates from drinks, gels and food is between 60-90g/hour. It is a good idea to experiment with different combinations of fluid, gels and foods during training and warm-up races to find the right combination for you. It is important to realise that we are all individuals and what works for your training partner might not work for you.

 

One common mistake by beginners is to eat too much on the bike leg. When completing the running leg, there is a lot of fluid and food sloshing around in the stomach. This can lead to gastro-intestinal discomfort, with feelings of bloating and nausea being common. Again, use your training to determine the optimal feeding strategy on the cycle leg, without compromising the run leg.

 

Because, there are many different types of triathlon events, and your training duration varies, the below table will help you to decide which is the best intake rate and type of carbohydrate to ingest.

Event Duration Carbohydrate Requirement Recommended Intake Carbohydrate Type Single Carbohydrate Multiple Types of Carbohydrate
< 30 min None None None None None
30-75 min Very Small Amounts Carbohydrate Mouth Rinse Most forms of carbohydrate OK OK
1 – 2 hr Small amounts Up to 30g/hr Most forms of carbohydrate OK OK
2 – 3 hr Moderate amounts Up to 60g/hr Ingestion of single carbohydrates (e.g. glucose, maltodextrin) OK, but not optimal OK
>2.5 hr Large amounts Up to 90g/hr Only multiple types of carbohydrates (e.g. maltodextrin and fructose) Not optimal OK

Taken from: Juenkendrup, A. (2011). Nutrition for Endurance Sports: Marathon, triathlon and Road Cycling. Journal of Sports Sciences, 29(S1), S91-S99.

 

Some interesting research that is just emerging is that your digestive system is trainable. By consuming carbohydrate during training, your body becomes better at absorbing and burning carbohydrate as you exercise. Therefore, train as you mean to compete and this includes incorporating race eating strategies into your training.

Hi there,

Last week I posted an assignment I wrote about high fat diets and endurance performance. The post was technical and may be understandable for sport scientists, but may not be easily understood by the lay person. So, in this post, I will try and explain the rationale and translate into practical guidelines.

Firstly, the protocol is that for 5-6 days prior to an endurance event (probably lasting longer than 1.5 hours – a marathon or half triathlon) you load up on fat in your diet. In practical terms, this equates to around 70% of calories from fat. Or, if you have the ability to weigh and monitor your food intake, this equates to 4.6g Fat/kg Body Weight/day. On the day before the event, we then change strategy and consume a high carbohydrate diet (70% calories or around 11g Carbohydrate/kg Body Weight/Day). This has the bonus of topping up our body’s carbohydrate (i.e. glycogen) stores.

The outcome of this strategy is that your body becomes more efficient and adept at burning fat. This is beneficial because we have huge amounts of energy stored as fat in our body, whereas we have limited amounts of carbohydrate. In endurance events of duration longer than 1.5 hours, the limited supplies of carbohydrate in our body may become an issue and may compromise performance. However, if we follow a high-fat diet, we tap into the bodies nearly unlimited supply of fat.

All well and good. But there is a caveat. By eating a high fat diet and turning up our bodies ability to burn fat as a source of energy, we compromise our body’s ability to burn carbohydrate. There is a trade off. Research has shown that high intensity performance is compromised in this scenario. Carbohydrate is a great source of energy at high exercise intensities, whereas fat isn’t. So, as a result, when we really start to push it in training or competition, our bodies ability to release energy from carbohydrate is dampened.

So, on a practical level, this is what I suggest. If finishing is the main outcome for you, then a high fat diet may help you to avoid the unpleasant consequences of “hitting the wall” or “the bonk”. You should be able to utilise your body’s store of fat to complete the event.

If, however, you have designs of winning or placing highly and you will really push yourself during the event, then I would suggest not following this strategy as you may not be able to give that high intensity spurt towards the end. In this case, I would advise some other strategies which will train your body to burn fat without compromising high intensity performance.

One of these strategies is the “train-low, compete high” scenario. In this, you train when your bodies carbohydrate levels are low. This trains your body to become more efficient at burning fat without compromising your ability to burn carbohydrate at high intensity.

This can be achieved in a number of ways:

  • Training first thing in the morning without having a breakfast.
  • Training twice a day. Eat very little carbohydrate between your first and second training session so that your carbohydrate stores are depleted.
  • On long training runs/cycles, do not consume any carbohydrate.

However, these are adavanced tactics. They should not be used by beginners and should only be used by advanced athletes sparingly (i.e. once a week).

Thanks for reading,

Kevin – Metabolise Sports Nutrition

Performance and Health Implications of High Fat Diets on Endurance Performance.

Athletes experiment with nutritional and training strategies to give themselves a competitive edge over rivals. Although high carbohydrate (H-CHO) diets are typically recommended for endurance athletes, some athletes have ignored this advice, consumed high fat (H-FAT) diets and have competed successful. Mark Allen and Jonas Colting are examples of two tri-athletes who have successfully followed H-FAT diets and won Iron Man and Ultra Man World Championships. Sparing limited glycogen reserves and increasing fat oxidation may be a viable strategy for improved endurance performance.

One of the first studies examining the effect of a high fat (H-FAT) diet on performance was undertaken by Phinney, Bistrian, Evans, Gervino & Blackburn (1983). Five endurance trained athletes consumed either a H-FAT (85% energy) or high carbohydrate (H-CHO) (66% energy) diet for four weeks. During a performance test after dieting, there was a decrease in the Respiratory Exchange Ratio (RER), a three-fold drop in glucose oxidation and a four-fold reduction in muscle glycogen use on the H-FAT diet, indicative of an increased rate of fat oxidation. Similar results were reported by other investigators (Goedecke, Christie, Wilson, Dennis, Noakes, Hopkins & Lambert, 1999; Helge, Watt, Richter, Rennie & Kiens, 2001).

Although H-FAT diets promote fat metabolism and glycogen sparing, one of the problems encountered by early investigators was that muscle glycogen was substantially reduced after a high fat diet due to low carbohydrate intake (Lambert, Speechly, Dennis & Noakes, 1994), which may negatively affect endurance performance (Bergström, Hermansen, Hultman, & Saltin, 1967). Therefore, later research utilised a dietary periodisation strategy, whereby glycogen loading would be undertaken after a period of H-FAT consumption, to replenish glycogen stores. Burke, Angus, Cox, Cummings, Febbraio, Gawthorn, Hawley, Minehan, Hargreaves & Hawley (2000) reported the effects a shorter adaptation period (5 days) with CHO restoration, comparing H-FAT (4g/kg/day) and H-CHO (9.6g/kg/day).  During 2 hours steady state exercise at 70% VO2 max, RER was reduced, fat oxidation increased and CHO oxidation decreased. Thus, even with CHO restoration and availability, exercising muscle preferentially oxidised fat as a fuel substrate.

Therefore, H-FAT diets promote fat oxidation and glycogen sparing during exercise. How might this work? Many of the cellular adaptations associated with H-FAT diets include increased enzymes involved in beta oxidation (Helge & Kiens, 1997), increased fatty acid transporters (Glatz, Luiken & Bonen, 2010) and increased mRNA concentrations of proteins involved in fatty acid transport and metabolism (Cameron-Smith, Burke, Angus, Tunstall, Cox, Bonen, Hawley & Hargreaves, 2003). Therefore, H-FAT diets up-regulate the metabolic machinery for the transport and oxidation of fats into the muscle cell and mitochondria.

How might H-FAT diets affect performance? Helge, Richter & Kiens (1996) divided subjects into H-CHO (65% energy) or H-FAT (62% energy) group for seven weeks followed by carbohydrate restoration in week 8. Subjects trained 3-4 times per week during the study period. After 7 weeks, time trial to exhaustion (TTE) at 81% of pre-training VO2 max increased from a mean of 35 mins to 102 mins in the H-CHO and 65 mins in H-FAT, with the improvement in performance significantly greater in the H-CHO group versus the H-FAT group. Even with a CHO restoration protocol in week 8, TTE improved slightly in the H-FAT group (77 mins) but was still significantly less than H-CHO TTE.

Other studies have demonstrated improvements in performance on H-FAT diets. Phinney et al. (1983) demonstrated that although there was no difference in time to exhaustion (TTE – cycle ergometer test at 62-64% of VO2 max) between the H-FAT and L-FAT diets, TTE increased by four minutes in H-FAT compared to baseline. However, closer inspection of the results revealed that one athlete had an abnormally large increase in TTE in week five while the other subjects either had no change or a decrease in performance.

Lambert et al. (1994) demonstrated an improvement in a cycle to exhaustion at 50% Peak Power Output (PPO) after a two week H-FAT (70% total energy) compared to H-CHO (74% total energy). There was no difference in cycle to exhaustion at 85% PPO. Carey, Staudacher, Cummings, Stepto, Nikolopoulos, Burke & Hawley (2001) examined the effects of H-CHO (11 g/kg/day  CHO, 1 g/kg/day FAT) or an isoenergetic high-fat diet (2.6 g/kg/day CHO, 4.6 g/kg/day FAT) diet for 6 days followed by CHO restoration on time trial performance. After cycling for 4 hours at 65% peak VO2 uptake, subjects on the H-FAT diet maintained an 11% non-significant (P=0.11) higher power output in a 1 hour time-trial task compared to H-CHO.

Therefore, the results from the effects of H-FAT diets on performance are equivocal. However, one observation is that performance in low and medium intensity exercise is enhanced. This might be expected, as substrate oxidation at these intensities is predominately fat (Van Loon, Greenhaff, Constantin-Teodosiu, Saris & Wagenmakers, 2001). If we look at exercising at higher intensities, a different picture emerges.

Stepto, Carey, Staudacher, Cummings, Burke & Hawley (2002) compared a three day H-FAT (4.6g/kg/day) or H-CHO (11g/kg/day) diet on high intensity interval exercise (8×5 min bouts at 86% VO2 peak) and reported higher Rate of Perceived Exertion (RPE) in the H-FAT versus H-CHO. Havemann, West, Goedecke, Macdonald, St Clair Gibson, Noakes & Lambert (2006) examined the effects of a six day H-FAT (68% energy) or H-CHO (68% energy) diet followed by carbohydrate restoration on a 100km TT interspersed with one kilometre sprints. This may be a more realistic scenario for elite performance compared to constant lower intensity performance trials. The one kilometre sprint power output was significantly lower in the H-FAT diet compared with the H-CHO diet.

Stellingwerff, Spriet, Watt, Kimber, Hargreaves, Hawley & Burke (2006) measured the effects of either a five day H-FAT (4.6g/kg/day) or H-CHO (10.3g/kg/day) diet, followed by carbohydrate restoration on 1 min sprint performance. Pyruvate Dehydrogenase activity was significantly reduced at rest and during low and high intensity exercise and estimated rates of glycogenolysis were reduced in H-FAT condition. This suggests that H-FAT diets work not through glycogen sparing but through glycogen impairment.

Intramuscular Triglycerides (IMTG) have been identified as an important fuel substrate during exercise, even at power outputs approaching 85% VO2 max in trained athletes. If undertaking high training volumes on consecutive days, athletes may need to consume higher than normal fat intakes (35-57% of energy) in order to replenish IMTG (Spriet & Gibala, 2004). Decombraz (2003) has suggested consuming a H-CHO diet in the initial 6-8 hours of recovery, with fat content increasing thereafter.

The World Health Organisation (2003) has recommended fat intakes of 15-35% of total energy intake for optimal health. Long-term H-FAT diets are associated with development of obesity, coronary heart disease and certain cancers (Manore, Meyer, & Thompson, 2009) and thus would not be recommended as a lifestyle choice. Acute fat intake results in transient suppression of muscle glucose uptake and muscle glycogen synthesis (Boden, 1997) and in the long-term may lead to insulin resistance, although this may be attenuated in endurance trained athletes (Goodpaster, He, Watkins & Kelley, 2001). However, training while fasting, during periods of hyper-caloric H-FAT intake, can improve whole body glucose tolerance and markers of insulin sensitivity (Van Proeyen, Szlufcik, Nielens, Pelgrim, Deldicque, Hesselink, Veldhoven, & Hespel, 2010). Training 3-4 times per week over seven weeks on a H-FAT (62% E) diet compared to a H-CHO (65% E) has been shown to reduce Natural Killer cell activity (Pedersen, Helge, Richter, Rohde & Kiens, 2000). This may compromise innate immunity and increase the risk of athlete infection. Therefore, there may be several adverse health consequences with consuming H-FAT diets.

From the research reviewed, it would be prudent to form the opinion that H-FAT diets, while increasing the ability to oxidise fat and spare glycogen at lower exercise intensities, reduces the ability to oxidise glucose at high intensities. Given that the outcome of all Olympic endurance events are decided at exercise intensities above 85% VO2 max (Joyner & Coyle, 2008), a compromised ability to oxidise glucose at high intensities would have negative consequences on elite performance. Long term H-FAT intake may compromise adaptations to training and may negatively affect health, although some of these ill effects may be attenuated by training. Reviews of the relevant literature do not recommend high fat diets to enhance performance (Hargreaves, Hawley & Jeukendrup, 2004) or training (Burke, Kiens & Ivy, 2004).

Using different nutrition practices (e.g. carbohydrate restriction before/during/after training – Hawley & Burke, 2010; Van Proyen, Szlufcik, Nielens, Ramaekers, & Hespel, 2011) or performing high-intensity interval training (Burgomaster, Howarth, Phillips, Rakobowchuk, MacDonald, McGee, & Gibala, 2008) may replicate many of the cellular and metabolic adaptations associated with H-FAT diets. High rates (1.75g/min) of exogenous carbohydrate oxidation can be achieved during exercise using multiple transportable carbohydrates (Jeukendrup, 2010), negating the need to protect glycogen stores. Short-term carbohydrate loading can increase muscle glycogen stores two-fold (Fairchild, Fletcher, Steele, Goodman, Dawson & Fournier, 2002). Strategies other than H-FAT diets are available to athletes to promote fat oxidation and boost glycogen stores without the need to compromise high intensity performance or health.

Reference

Bergström, J.,  Hermansen, L., Hultman, E., & Saltin, B. (1967). Diet, muscle glycogen and physical performance. Acta Physiologica Scandinavica, 7(2-3), 140-150.

Boden, G. (1997). Role of fatty acids in the pathogenesis of insulin resistance and NIDDM. Diabetes, 46(1), 3-10.

Burgomaster, K.A.,  Howarth, K.R.,  Phillips, S.M.,  Rakobowchuk, M.,  MacDonald, M.J., McGee, S.L. & Gibala, M.J. (2008). Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans.  Journal of Physiology, 586(1), 151-160.

Burke, L.M., Angus, D.J., Cox, G.R., Cummings, N.K., Febbraio, M.A., Gawthorn, K., Hawley, J.A., Minehan, M., Martin, D.T., & Hargreaves, M. (2000). Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling. Journal of Applied Physiology, 89(6), 2413-2421.

Burke, L.M., Kiens, B., & Ivy, J.F. (2004). Carbohydrates and fat for training and recovery. Journal of Sports Sciences, 22, 15-30.

Cameron-Smith, D., Burke, L.M., Angus, D.J.,  Tunstall, R.J., Cox, G.R., Bonen, A., Hawley, J.A., & Hargreaves, M. (2003). A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle. American Journal of Clinical Nutrition, 77(2), 313-318.

Carey, A.L., Staudacher, A.M., Cummings, N.K., Stepto, N.K., Nikolopoulos, V., Burke, L.M., & Hawley, J.A. (2001). Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise. Journal of Applied Physiology, 91(1), 115-122.

Decombaz, J. (2003). Nutrition and recovery of muscle energy stores after exercise. Sportmedizin und Sporttraumatologie, 51(1), 31–38.

Fairchild, T.J., Fletcher, S., Steele, P., Goodman, C., Dawson, B., & Fournier, P.A. (2002). Rapid carbohydrate loading after a short bout of near maximal-intensity exercise. Medicine and Science in Sports and Exercise, 34(6), 980-986.

Goedecke, J.H., Christie, C., Wilson, G., Dennis, S.C., Noakes, T.D., Hopkins, W.G., & Lambert, E.V. (1999). Metabolic adaptations to a high-fat diet in endurance cyclists. Metabolism, 48(12), 1509-1507.

Goodpaster, B.H., He, J., Watkins, S., & Kelley, D.E. (2001). Skeletal muscle lipid content and insulin resistance: evidence for a paradox in endurance-trained athletes. Journal of Clinical Endocrinology Metabolism, 86(12), 5755–5761.

Glatz, J.F.,  Luiken, J.J., & Bonen, A. (2010). Membrane fatty acid transporters as regulators of lipid metabolism: Implications for metabolic disease. Physiological Review, 90(1), 367-417.

Hargreaves, M., Hawley, J.A., & Jeukendrup, A. (2004). Pre-exercise carbohydrate and fat ingestion: effects on metabolism and performance. Journal of Sports Sciences, 22, 31-38.

Havemann, L.,  West, S.J.,  Goedecke, J.H., Macdonald, I.A.,  St Clair Gibson, A., Noakes, T.D. & Lambert, E.V. (2006). Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. Journal of Applied Physiology, 100(1), 194-202.

Hawley, J.A., & Burke, L.M. (2010). Carbohydrate availability and training adaptation: Effects on cell metabolism. Exercise and Sport Sciences Reviews, 38(4), 152-160.

Helge, J.W., & Kiens, B. (1997). Muscle enzyme activity in humans: role of substrate availability and training. American Journal of Physiology, 272(5), 1620-1624.

Helge, J.W., Richter, E.A.,  & Kiens, B. (1996). Interaction of training and diet on metabolism and endurance during exercise in man. The Journal of Physiology, 492(1), 293-306.

Helge, J.W., Watt, P.W., Richter, E.A., Rennie, M.J., & Kiens, B. (2001). Fat utilization during exercise: adaptation to a fat-rich diet increases utilization of plasma fatty acids and very low density lipoprotein-triacylglycerol in humans. The Journal of Physiology, 537, 1009-1020.

Jeukendrup, A. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), 452-457.

Joyner, M.J., & Coyle, E.F. (2008). Endurance exercise performance: the physiology of champions. Journal of Physiology, 586(1), 35-44.

Lambert, E.V., Speechly, D.P., Dennis, S.C., & Noakes, T.D. (1994). Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. European Journal of Applied Physiology and Occupational Physiology, 69(4), 287-93.

Manore, M.M., Meyer, N.L. & Thompson, J. (2009). Fat as a fuel for exercise. In M.M. Manore, N.L. Meyer and J. Thompson (Eds.), Sport nutrition for health and performance (2nd ed.) (pp. 77). Champaign, IL: Human Kinetics.

Pedersen, B.K., Helge, J.W., Richter, E.A., Rohde, T., & Kiens, B. (2000). Training and natural immunity: effects of diets rich in fat or carbohydrate. European Journal of Applied Physiology, 82(1-2), 98-102.

Phinney S.D., Bistrian, B.R., Evans, W.J., Gervino, E., & Blackburn, G.L. (1983). The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism, 32(8), 769-776.

Spriet, L.L., & Gibala, M.J. (2004). Nutritional strategies to influence adaptations to training. Journal of Sports Sciences, 22, 127-141.

Stellingwerff, T.,  Spriet, L.L.,  Watt, M.J., Kimber, N.E., Hargreaves, M., Hawley, J.A., & Burke, L.M. (2006). Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. American Journal of Physiology –  Endocrinology and Metabolism, 290(2), 380-388.

Stepto, N.K., Carey, A.L.,  Staudacher, H.M.,  Cummings, N.K., Burke, L.M.,  & Hawley, J.A. (2002). Effect of short-term fat adaptation on high intensity training. Medicine and Science in Sports and Exercise, 34(3), 449-455.

Van Loon, L.J.C.,  Greenhaff, P.L., Constantin-Teodosiu, D., Saris, H.M., &  Wagenmakers, A.J.M. (2001). The effects of increasing exercise intensity on muscle fuel utilisation in humans.  Journal of Physiology, 536, 295-30

Van Proeyen, K., Szlufcik, K., Nielens, H., Pelgrim, K.,  Deldicque, L., Hesselink, M., Van Veldhoven, P.P., & Hespel, P. (2010). Training in the fasted state improves glucose tolerance during fat-rich diet. The Journal of Physiology, 588(21), 4289-4302.

Van Proeyen, K., Szlufcik, K., Nielens, H., Raemakers, M., & Hespel, P. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1), 236-245.

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Metabolise Sports Nutrition

Hello,

It being winter here in the northern hemisphere, and with many athletes getting back into training after the Christmas break, thoughts turn to how to prevent illnesses in this vulnerable timeframe. Athletes are liable to dose up on additional vitamin and minerals in order to boost their immune systems and to help prevent colds, flus, URTIs etc.

It therefore came as a surprise to me to read this review which looked at the effects of vitamin and mineral supplementation on illness prevention in athletic populations. The findings will not be pleasant reading for the manufacturers of vitamin and mineral supplements.

The authors concluded that the following supplements have no proven benefits in preventing illness in athletes:

  • Vitamin E
  • Vitamin C
  • Multiple vitamin and minerals
  • Glutamine
  • BCAAs
  • Fish Oil (N-3 PUFAs)
  • Beta-glucan
  • Herbal Supplements (e.g. ginseng)

The jury is still out on the following supplements:

  • Bovine Colostrums
  • Probiotics

The only supplements that the authors recommend are carbohydrate (which athletes will probably be eating large quantities of anyway), and quercitin, a flavaoid widely found in fruit, vegetables, grains and leaves. It seems that the best way to prevent those winter sniffles is to eat a balanced and varied diet.

Kevin Beasley

This being my first blog post, and the last day of 2011, I would like to begin with a brief review of the most thought provoking nutrition book that I’ve read this year. The book is called “Good Calories, Bad Calories” by Gary Taubes.

Taubes builds a compelling case, based on scientific evidence, that everything we thought we knew about how the human body regulates weight is wrong. The basic premise is that all calories aren’t equal, and it is the increase in carbohydrate consumption – and especially refined carbohydrates – that have been the ignition for the obesity crisis. Eating carbohydrates has an inpact on the release of insulin. Chronic consumption of refined carbohydrates results in abnormalities in the release of insulin and our bodies ability to deal with carbohydrates. As a result, chronic elevation of insulin results in increased storage of  carbohydrates in fat tissue and a decreased ability of our bodies to burn fat.

To summarise some of the fascinating insights in the book:

  • Obesity is actually a disease of malnutrition. Our fat tissue takes all the energy for itself, meaning that the rest of the bodies cells are starved.
  • Obesity causes tiredness/laziness and over-consumption of food – and not the other way around.
  • The body has an intrinsic, finely-tuned system that regulates food intake in response to our energy expenditure and needs. This system is disrupted by over-consumption of refined carbohydrates.
  • For sedentary people, the food pyramid is upside down. We should be consuming more fats and protein, and less carbohydrate. This is probably the one single thing that has provoked the obesity crisis.

While this book is aimed at the obesity crisis, and ways of dealing with it, I believe the implications are also relevant for sports nutrition, especially for weight category sports. Strategies can be designed, based on this book, for safe and effective ways of obtaining the ideal physique for your sport. It goes without saying that reduction in carbohydrate intake is the main basis of this strategy.

This book is a weighty tome, weighing in at over 600 pages, and is probably suitable for someone with a scientific background. However, a more basic version of this book, called “Why we get fat – and What to do about it” is available and may be more suitable for the layperson or general public.

Overall, whether you are a scientist, dietitian, nutritionist or Joe Bloggs, I would highly recommend reading this book. It will change the way you view food….

Happy New Year,
Kevin Beasley