Eating for a Marathon: Eating Enough

One of the most common issues I see as sports nutritionist is athletes not eating enough. Strangely, it doesn’t seem to matter if they are trying to lose, gain or maintain their weight. And more often than not, it is completely inadvertent. Training increases but the athlete keeps eating the same amount as before. Or they follow the recommended portion sizes on packaging, which are for a 2000 kcal diet – when they are burning over 3000 kcal per day!

Not eating enough can lead to a syndrome known as Relative Energy Deficiency in Sport (RED-S) (previously known as the Female Athlete Triad). Symptoms include:

  • Irregular or missed periods in women and low testosterone in men
  • Decreased adaptation to training (you don’t progress) and decreased performance in competition, despite training harder than ever
  • Low mood and fatigue, despite getting enough sleep
  • Frequent injuries, particularly bone injuries like stress fractures
  • Frequent illnesses like colds and flu
  • Poor body composition – you can’t gain muscle mass or lose body fat

The second item on the list was of particular concern to me. My goals this year are all about performing well in the marathon – not losing body fat or looking a particular way. To set a new marathon PB, I needed to hit all my training targets. That meant I needed to eat enough to go hard in training, recover, and go hard again the next day. As my mileage and hours of training increased, so did the number of extra calories I had to consume. And it quickly became apparent just why so many of my athletes struggle to eat enough! Turns out, it can be hard to eat more than 3000kcal per day while sticking to healthy foods.

It was tempting to just add more treats to my diet. After all, junk foods – like cake or chips – taste so good because they are loaded with fat, salt and simple carbs (sugar, white flour, etc). This ramps up the calorie count. And I did sometimes have more cake or ice cream than I normally would. Problem is, these foods lack the protein, vitamins, minerals and antioxidants that speed up recovery. So you get the calories, but not much else in the way of nutrition.

Long run days, where I would burn over 1000 extra calories, were a particular challenge. After a bit of trial and error, I did find some meals that were both nutrient and calorie dense. For example, my typical breakfast before a long run is porridge made with gluten free oats, skim milk, a small chopped apple, ground flaxseed, raisins, pumpkin and sunflower seeds. Together with a large mug of tea with milk and sugar, that’s over 700Kcal and over 100g of carbs. And that fuel is a mix of both complex carbohydrates (oats), simple sugars (in the fruit) and healthy fats (from the seeds).

In the end, I used a variety of techniques to increase my calorie intake without resorting to a load of fat laden junk food. I increased the portion sizes of my usual healthy foods, which took some getting used to. In particularly, I needed enough complex carbohydrates to fuel training, like oats, sweet potatoes, quinoa, pasta, etc. If I had a particularly heavy training session, I would have a couple different carbohydrate sources in the same meal, such as butternut squash in a risotto, or a curry with both rice and naan bread. I also added more healthy fats to my diet, mostly from nuts, seeds and oily fish. And I did enjoy some higher calorie, higher fat foods like cheese (high in calcium and protein) and liver pate (high in iron, which is often low in runners).

In August I went for a second round of physiology testing, and it was all good news. My VO2 max had gone up by 6%, my lactate thresholds had shifted to higher speeds, and I was using more fats as fuel. Not to mention the new half marathon PB I also had in August. Eating enough to fuel proper hard training works!

Eating for a Marathon: Carb Loading

Part of marathon preparation is doing some shorter races in the lead up to the big day. Shorter races can be a good gauge of how your training is progressing – many people set new personal best times at shorter distances when training for a marathon. Shorter events also give you the chance to practice all your routines around racing – training the week before, your clothing choices, pacing during the race, and of course, your nutrition.

I had looked to do at least one 10K and a half marathon before my full marathon in October, but those races were cancelled. So, with the help of my husband, I did a couple of faux races. This involved getting up bright and early, going through my pre-race routines (same breakfast, warm up, etc.), driving to a park 20 minutes away (so I was less familiar with the route), and starting at exactly 9am. For the half marathon I even did a full, three day, carb loading diet – and boy, was that an eye opener!

Carbohydrates are stored in the liver and muscles as glycogen. When we exercise, that glycogen is broken down for energy. The higher the intensity of the exercise, the faster you burn through your glycogen stores. In training, having slightly depleted glycogen stores is normal, and can even encourage the body to use fats as fuel (see the previous post on Using Fats as Fuel). However, in a race situation, you want all the carbs you can get to maximise performance.

Carb loading is when an athlete eats a lot of carbohydrates in the days before a race, to maximise glycogen stores. Generally speaking, you only need to do this if the race will last more than 90 minutes. There are various ways to carb load, but recent research has shown that eating at least 6g/Kg of carbohydrate, and up to 12g/Kg, in the 2-3 days leading up to the race is enough to fully top up glycogen stores1. Especially as most people are resting or training very lightly in the days leading up to their race.

This is well known and I have dispensed this advice to my athletes for years. What I didn’t realise is just how much carbohydrate that is, and how hard it is to eat that much! Especially if you are trying to keep the calorie count within reason. For example, I weigh 62 Kg so 6g/Kg is 372g of carbohydrate, so that’s my minimum target. The day before my half marathon I ate:

Breakfast: Two boiled eggs with two gluten free crumpets topped with butter and jam, a 200ml glass of pineapple juice, and a large mug of tea with milk and sugar.

Morning Snack: A mug of tea with milk and sugar and two small, gluten-free custard creams.

Lunch: Small grilled mackerel fillet with plenty of rice, steamed broccoli and carrots. Watermelon for dessert followed by a mug of tea with milk and sugar and two small, gluten-free custard creams.

Afternoon Snack: Three slices of toasted gluten free bread topped with reduced fat Brussels pate and caramelised red onion chutney, with 36g of dried apricots on the side. Two satsumas (small oranges) shortly afterwards.

Dinner: Free from spaghetti with homemade tomato sauce and a beef and lentil meatball, topped with a small amount of Parmesan cheese. Frozen yoghurt ice lolly.

In total that was 2660 kcal – at least 500kcal more than I would normally eat on a rest day. Of that, 411g was carbohydrates, including 146g of sugar – well above the recommended. That’s only 6.6g/Kg of carbs and I have to say I felt stuffed! I can’t imagine eating the amount of food an 80 Kg runner would have to take in to get above 7 or 8g/Kg of carbs. Even though, as a nutritionist, I have created menu plans that do exactly that!

You’ll notice my intake of processed foods was well above normal – I am not in the habit of having crumpets, bread and biscuits all in the same day! Part of that was trying to avoid too much fibre. We get most of our fibre from carbohydrates (wholegrains, vegetables, etc.), so carb loading can mean a big increase in fibre. Normally a high fibre diet is good, but too much fibre too close to a race can lead to gasto distress during the race. So many athletes switch to lower fibre, “white” carbs when carb loading. Hence my breakfast of crumpets rather than the usual porridge.

There was also 88g of protein (1.4g/Kg) and 73g was fats. This is a perfectly healthy amount of both but probably too much when carb loading. At the time I chose mackerel because it’s an oily fish high in Omega 3 fatty acids, which reduce inflammation and help with recovery. And I had pate on my toast because it’s high in iron (often low in runners) and vitamin A. However, both are high in fat and in hindsight, I’m not sure I need. I could have kept the calorie count down by choosing lower fat white fish and a lower fat, high carb toast topping (like honey or jam).

Is carb loading worth it? Yes! I had a really good half marathon, setting a new PB. But if I’ve learned anything, it’s that carb loading is more complicated than even I thought (as demonstrated by the length of this post)!



1. Vitale, K. and Getzin, A. 2019. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019 Jun; 11(6): 1289. doi: 10.3390/nu11061289

Eating for a Marathon: Weight Loss

Last week I talked about some of the techniques I used to encourage my body to use fats as fuel. Most people assume that burning more fat during exercise will result in weight loss.  Sadly, this is not true. To lose weight, you need a calorie deficit – to be taking in less energy than you use. No calorie deficit, no weight loss, as I experienced first hand.

Like most people, I put on a few pounds over Christmas, and on 1 January 2020 I weighed in at 65.7Kg and 30% body fat. I had lost some body fat in January and early February, but I then went to Canada for a couple of weeks for a wedding. When I got back, I weighed 65.4 Kg and 29% body fat – basically back to where I was in early January. As I got back into training, I was hoping the healthier eating and increased running would lead to fat loss.

By the first of April I was down to 64Kg. However, despite an ever increasing training regime, I stayed at 64Kg and 29% body fat. Health and aesthetic benefits aside, I had another reason for wanting to shed some weight. Studies have shown that runners are, on average, two seconds per mile faster for every pound they lose. If I lost 5lbs of fat, I should be a good 4 minutes faster over the course of a marathon.

So I decided to switch up my training and nutrition for a couple of weeks to encourage weight loss. Up to that point, I’d been eating a base of around 1800Kcal per day, then adding exercise calories on top. For example, if I burned 400Kcal on a run, I ate 2200kcal that day. From the 18th of May, I switched to a 1500kcal base. I was still adding the exercise on top, so in reality I was often getting 2000kcal per day.

To ensure I was losing fat and not muscle, I increased by protein intake – at least 1.8g/Kg per day. I did keep carbohydrates in my diet, but was much more strategic in when I had them. I tried to have higher carbohydrate meals after exercise, and lower carbohydrate meals at other times. I also kept an eye on the amount of fat in my diet, to keep the calorie count down. But it wasn’t exactly a low fat diet either. Of course, there was no alcohol and very few refined sugars (the kind you find in chocolate, cake, etc.).

I also switched up my training to further encourage fat burning. On Mondays, Wednesdays and Fridays I went for a 45 minute walk before breakfast, while on Tuesdays and Thursdays, I did an hour long fasted run. I kept my hill sprints on Monday afternoons, and my long run on Saturdays. I was up to an hour and a half on the long run, so I did have breakfast before, but I didn’t take on any carbs during the run. There were also a couple of HIIT/strength training sessions per week (as normal) and I made an effort to get 10,000 steps a day, most days of the week.

And it worked. On June first I weighed in at 61.8Kg and 26.3% body fat. In two weeks I had lost over 2kg and most of that was body fat, not muscle. However, it was not easy. I was often tired and hungry, despite a high protein and high fibre diet. And the quality of my hill reps and HIIT sessions really suffered – I just didn’t have the energy to push myself.

In some ways losing weight to get faster is a short cut. In two weeks I lost enough weight to take 4 minutes off my marathon time. It could take months to get that much from training. And it can be tempting to keep going, especially when you know you have plenty of body fat to lose (26% body fat is high for a runner). But it is a game that catches up with you in the end – as I discovered, your training really suffers.  I decided that I would get better results by hitting all my training targets, rather than chasing a lower body weight.

The good news is that on September second I was still 61.8 kg –  no more, no less. All while fuelling ever increasing amounts of training!

Please note: This is a description of my personal experience of losing body fat to meet a specific performance goal. It is not meant to be taken as a recommendation for anyone else. Using these techniques to lose weight may not be appropriate for you and your circumstances.

Eating for a Marathon: Using Fats as Fuel

As it turns out, nine months is a long time to be training for one event. So like most athletes, I do follow a periodized training plan, where different phases of training have slightly different goals. Being a sports nutritionist, I also have different nutrition goals to support my training during my different phases. And one of my first goals was to improve my body’s ability to use fats as fuel.

The Why

As a sports scientist I love data. So in January, I booked in for some physiology testing at Loughborough University. The information you get from this type of testing can then guide your training – do I need more long slow runs to build my aerobic base, or more high intensity intervals to improve VO2 max?

Aside from showing how little running fitness I had in general, the testing showed I was relatively poor at using fats for fuel, even at very low speeds. This is a particular problem for slower marathoners such as myself. See, even highly trained athletes can only store enough carbohydrates to get through 60-90 minutes of exercise. Of course, you can top up your carbohydrate stores during exercise by having energy gels or sports drinks, but most runners can only tolerate 60g of carbohydrates per hour (or less).

Based on previous experience, I will be burning at least 60Kcal per Km, which is over 2500Kcal for a whole marathon. Assuming I have enough carbs stored in my muscles for the first hour (about 550 Kcal), then take in 60g of carbs per hour (about 960 Kcal), that leaves 1000Kcal my body has to get from somewhere. If I can teach my body to use fats as a fuel over carbohydrates, then I am less likely to run out of energy before the end of the race.

The How

The easiest way to force your body to use fats as fuel is to eat a high fat, low carbohydrate diet. However, I’ve been down that road before, and I can’t say it appeals. Especially as I would have to maintain such a diet for over 9 months of training! Plus, research has shown that while high fat diets can increase time to exhaustion in endurance tests, top end sprint speed and power tend to decrease1. You wouldn’t think that matters in the marathon, especially for someone targeting four and half hours. But another result of my testing was a need to improve my VO2 max and overall running speed. That meant regular sprint intervals and faster paced training sessions. To get the most out of these sessions, I would need full carbohydrate stores.

An alternative way to encourage fat burning is to periodize your carbohydrate and fat intake2. This involves eating more carbohydrates on days with high intensity, high speed sessions, and fewer carbohydrates on rest and easy days. You can also teach your body to use fats as fuel by fasting and incorporating fasted training into your plan3. This is where you go for a run first thing in the morning before breakfast, after your usual overnight fast (about 12 hours since dinner). As you will have used up most of your carbohydrates as you sleep, your body is forced to rely on fats for fuel. It does feel harder, which is why these runs tend to be less than an hour at an easy pace.

Here’s an example of how I incorporated periodized carbohydrate intake with fasting into my training (in March, April and early May):

  • Monday: Moderate to high carbohydrate diet. Sprint interval session on hills in the afternoon.
  • Tuesday mornings: Fasted easy run before breakfast, then eat normally the rest of the day (moderate carbohydrate ~4g/kg).
  • Wednesdays: Rest day. Small, very low carbohydrate breakfast (usually a two egg cheese omelette) and fasted for the rest of the day (only water and green tea).
  • Thursday: Higher carbohydrate breakfast and lunch (more than 1g/kg carbohydrate in each meal) before a marathon pace run on Thursday afternoon. Back in March, marathon pace was a Tempo run (a pace I could only sustain for 15-20 minutes).

The Result

I would not recommend the above schedule to everyone, but it seemed to work for me. I was able to increase the pace of my long, slow runs while keeping the same effort (I use a heart rate monitor), indicating I was getting better at using fats for fuel. It did have it’s drawbacks though, which I will discuss in the next post.

When it comes to sports nutrition, I it very true that everyone is an experiment of one.


As always, there are many papers on this topic, but I have tried to provide open access ones.

  1. Burke et al. 2020. Adaptation to a low carbohydrate high fat diet is rapid but impairs endurance exercise metabolism and performance despite enhanced glycogen availability.
  2. Jeukendrup, A. 2017. Periodized Nutrition for Athletes.
  3. Aird, TP et al. 2018. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. 10.1111/sms.13054

New Series! Eating for a Marathon

Warning! This is going to get personal.

I’ve been running a lot this year. Many people took up running in March, as a way to get outside and exercise while gyms were closed. However, my running journey began in December. After a difficult and disappointing 2019 (including a death in the family) I decided I needed a new big goal to refocus my training. I had run my first marathon with my husband in 2018, but bad weather and inconsistent training meant a disappointing time. So I decided 2020 was the year I would tackle 42.2 Km properly, with 9 months of dedicated training.

Many things did not go well when I rant my first marathon in October 2018. Training had been inconsistent throughout the summer months (among other things, I took a trip to Canada) and my longest run before the race was only 24 Km. On the day it was cold, pouring with rain and quite windy. Our chosen race had a very dodgy route in the middle miles, including running next to busy roads with no pavement. From 30 Km in, we started taking longer and longer walk breaks. Needless to say, it was not a good time – in either sense of the word. The one bright spot is that we did, in fact, finish the race.

Knowing the beast that awaits and the number of things that can go wrong, I’ve set several goals this time around. To start, just finishing the race without walking (except where necessary, such as at busy aid stations) would be a step up. Secondly, to set a new personal best time – so anything under five and a half hours. Thirdly, should training go well and the weather co-operate on the day, to run the marathon in less than four and half hours. This last is a significant stretch as, at the beginning of January, I couldn’t even manage 5 Km at the pace I would have to sustain for 42 Km come October.

Strangely, going into lockdown in March produced some of the most consistent training I’ve ever had. With very few fixed time commitments  sticking to my marathon training plan became a way of scheduling my days. I also had more time to focus on recovery such as stretching and foam rolling, or even taking a nap if needed. As my runs got longer, I couldn’t help wondering how anyone does serious marathon training with a full-time job.

Of course, for me, part of getting my training right was getting my nutrition right. Even after years of successfully advising a variety of endurance athletes on their nutrition, the realities of doing it for myself produced some surprising insights. This is what I will be sharing in a new series of posts. Everything from eating for training and long runs, to carb loading and weight loss. Yes, this is nutrition for runners, but much of the information will apply to anyone who is active, whatever their goals.

Sadly, like so many others, the race I had registered for in October has now been cancelled. But having come this far, I still plan to run 42.2 Km on the day as planned. As Garmin is my witness, a marathon is going to happen!

Why Protein is King for a Lean, Toned Physique

It’s the holy grail of most athletes at every level: How to gain muscle mass while losing body fat. More and more, I’m seeing athletes who are a healthy weight, but have higher levels of body fat than you would expect from their level of training. So this month I’ll be looking at what you should eat to encourage fat loss, without sacrificing muscle mass or performance. Starting with something we’re hearing a lot about lately: Protein.

For all the hype about effects of fats and carbohydrates on fat loss and athletic performance, the first thing to get right is the amount of protein in your diet. Protein is necessary to grow and repair body tissues, including muscle. And when you exercise, you damage your muscles and other tissues. If you are not eating enough protein, your body will be unable to turn all that training you’re doing into increased strength and stamina. What’s more, simply eating 20g of protein causes an increase in muscle protein synthesis (muscle building). If you spread your protein throughout the day, you can stimulate muscle building after every meal and snack. The more muscle you have, the more calories you burn at rest. This is why the muscle building combination of more protein and exercise can really accelerate fat loss.

When you go on a calorie restricted diet, your body breaks down both stored fat and muscle to make up the energy deficit. The more restrictive the diet and the faster the weight loss, the more likely it is that the weight is coming from muscle and water as well as fat (this is why I keep emphasizing that the goal is fat loss, not weight loss!). However, research has shown that consuming a high protein diet can counteract this.  Protein is also the most satiating of all the macronutrients – it makes you feel full, which makes it easier to eat less. It can also reduce cravings for sweets treats. Strangely enough, sometimes when people crave sweets, especially after a workout, what their body actually needs is more protein.

The current guidelines are for 0.6g of protein per kilogram of bodyweight per day for a sedentary person. However, if you are an athlete looking to drop body fat, you need at least 1.5g per kilo per day, and up to 2.4g per kilo if you are cutting calories. For example, if you weigh of 70kg (11 stone), that’s 105 to 168g of protein per day. This may sound like a lot but is quite doable if you include protein with every meal and snack. For example, you could have eggs with breakfast, a tuna sandwich and a glass of milk for lunch, yoghurt and nuts as a snack, and chicken and veg for dinner.

If it’s a lean, toned physique you’re after, plan your meals around protein!

Post Race Recovery

It’s been three days since I completed my first 10Km race in three years. After the brutal conditions I expected to feel tired for days and have a fair amount of DOMS (delayed onset muscle soreness). I was also concerned that in my depleted state I might pick up a cold or flu. However, three days most race I am pain and cold free! It seems my recovery strategies have helped my body heal the worst of the damage. The true test will come later today when I try a gentle 20 minute run – the first proper exercise since my race.

I’ve written before about the benefits of a balanced, and timely, recovery meal. Essentially, all exercise uses energy and causes damage to your muscles. In order to get fitter and stronger, you need to make sure your body has everything it needs to repair the damage. This includes protein to build new muscle and carbohydrates to replenish energy stores. If you can also get some antioxidants to help mop up all the free radicals released by hard exercise, so much the better. The faster you get these into your system, the sooner recovery can start. However, after a major event like a race or competition, what you eat in the following 2-3 days can determine how fast your recover and if you fall ill.


The first thing to avoid is excessive celebrating, especially too much alcohol. After an endurance race you will be dehydrated, so part of recovery is rehydrating as quickly as possible. Equally important is staying hydrated over the next couple of days. While a post race drink is certainly called for, alcohol is a diuretic, so will make dehydration worse. Since many of the symptoms of a hangover are actually dehydration, you may find you get a much worse hangover on far fewer drinks the night after a race.


Too much celebrating with loads of sugary treats can also be a problem. After a hard race you will have a significant amount of muscle damage. In order to repair this damage, your body triggers an immune response, including inflammation. In fact, it is the swelling and breakdown of damaged muscles which causes much of the pain of DOMS. The problem with sugar is that it increases inflammation. Yes, some sugar after a race will help refill your depleted glycogen stores. And you’ve certainly earned that slice of cake!  But a constant supply of sugary treats in the days following a race encourages excessive inflammation, which may delay recovery.

Junk Food

Some athletes also fall into the trap of letting all their healthy eating habits go after a race. After all, they’ve earned a few days of pizza, beer and burgers, right? This is especially likely to happen if the athlete in question has been following quite a strict eating plan in the run up to the race. Unfortunately, after a hard race is when your body needs fruit and veg the most. This is because a hard race suppresses your immune system. This increases your chances of catching a cold or flu. However, you can support your immune system with plenty of vitamin C. Studies have shown that marathon runners with the highest fruit consumption are the least likely to get ill in the days following a race.

In my case, I haven’t found alcohol to be a particular temptation, and I’ve returned to my regular high fruit and veg diet. No, my vice is sweet treats following the race. In this case, gluten free Bramley apple pies. Specifically, an entire pack of pies eaten in one go, all 900 calories of them – which is more than I burned in the race. And I’ve felt myself craving more in the past couple of days. Fortunately, my usual strategy of not buying junk food as part of a regular grocery shop is paying off. Between work and recovering from my race, I’ve been too tired to walk to the shop for more pies!

My first proper cross country race

Regular readers will know that I have spent the past six weeks training for a 10Km race. This is a particular challenge for me as I have spent the past two years focusing on javelin throwing. In other words, on strength and power rather than endurance and speed. So it was with some trepidation that I prepared for my race yesterday.

Sunday dawned clear and sunny but quite cold – the forecast was for 3 C at race start time. Upon arriving at the venue, a county park, I quickly realised I had made a true rookie mistake – not properly investigating the type of race I had signed up for. I was envisaging some firm gravel paths through the forest with a couple of short, gentle hills. Not so much.

They’d had quite a bit of rain over the past few days, which meant large parts of the course reminded me of the Tough Mudder we had in September. The terrain consisted of long wet grassy bits, ankle deep muddy bits, and boggy bits, interspersed with the occasional section on a firm path or road. And most of the course was long, steep hills, some on very narrow, very muddy paths which had everyone walking/sliding up single file. Plus, the cold weather meant pockets of ice in particularly shady spots under the trees. My husband referred to it as a proper cross country race – and he’s from Yorkshire!

To say it wasn’t a fast course is an understatement. There was the usual mix of people running the race, including some very fit fell runner types at the front. Normally a race like this will attract some decent club runners, who will finish in about 35-38 minutes. Yesterday the winner took almost 43 minutes to get round! About 15% longer than they would have normally. So I am very proud of the fact that I managed to complete the course in an equivalent 15% longer than I was originally planning for.

What’s more, while the terrain had me (and everyone else) walking a couple of times, I never felt the need to stop or walk. I had the fitness to run at a good pace on all the sections that were runnable, and a couple that probably weren’t (but I ran them anyway. Actually, I’m amazed no one broke an ankle). I also never felt I was running out of gas despite taking longer than planned, and only taking a couple sips of water at the halfway point.

Overall I was very pleased with my performance, even if I was nowhere near my time goal. It did leave me thinking that I really should try a fast road race soon. Because if I can manage to run 10 Km in such conditions, surely, I can post a new PB on a flatter, more solid course. I may have been bitten by the racing bug!

Why athletes get to eat more sugar

This week I’ve been discussing the different types of sugars and why most sugars are so bad for you. However, there are exceptions to every rule. One of the joys of serious endurance training is the guilt free consumption of simple sugars.

During exercise your body uses a combination of carbohydrates and fats for energy. When you exercise at low intensities, more of your energy comes from burning fat. But as intensity increases, your body uses a higher proportion of energy from carbohydrates. The more intense the exercise, the more carbohydrates you will use. All carbohydrates you eat are converted into glucose (a simple sugar). Glucose is stored in the liver and muscles as glycogen, usually enough to last for 90 to 120 minutes of moderate exercise. The problem is, if you are going to be exercising for more than 90 minutes, odds are you will run out of glycogen. This is known as “hitting the wall” or “bonking”.

The easiest way to avoid this is to take in more carbohydrates during exercise. And you need these carbohydrates to be easy to digest so the glucose hits your bloodstream as soon as possible. So this is one of the few times nutritionists will recommend simple sugars. This is the time and place for full sugar sports drinks, energy gels, energy bars, even sweets like jelly babies. What’s more, simple sugars are less likely to cause stomach upset than foods with protein, fat and fibre.

You can also use simple sugars to help your body recover from exercise. After exercise you need carbohydrates to replace the glycogen stores you’ve used up and protein to repair your damaged muscles. The faster these get into the muscles, the sooner repair and recovery can begin. By having a recovery meal with simple sugars, you can cause an insulin spike that encourages your muscles to absorb the glucose (from carbohydrates) and amino acids (from protein) from your bloodstream. This is why the ideal recovery meal is a mix of protein and both simple and complex carbohydrates. Think a glass of milk (protein and simple sugars) with a couple slices of toast (complex carbs) and jam (simple carbs).

Normally a large insulin spike is a bad thing. Our lifestyles mean most of us get very little exercise, so we don’t use up much stored glucose. We then eat plenty of sugar so the pancreas has to make more and more insulin to force the already full cells to store more glucose. But if you have depleted the glucose stored in your cells with some hard exercise, then an insulin spike is just the thing to refill them.

This is why the strategic use of sugar can help athletes perform better and recover faster than avoiding sugar completely!

Beating the Heat in Hawaii

The Ironman Triathlon World Championship takes place this weekend in Kona, Hawaii. If you haven’t heard of it, an ironman triathlon consists of a 2.4 mile swim, a 112 mile bike ride, and a full 26.2 mile marathon. Serious elites will finish the race in 8 or 9 hours, while the average triathlete will take over 12 hours. The World Championship held every year in Hawaii adds another challenge: the heat.

Any Ironman presents a serious nutrition challenge. Carbohydrates are the body’s main energy source, and the preferred energy source during exercise. In the body, all carbohydrates are converted into glucose (a simple sugar). Glucose is stored in the liver and muscles as glycogen, usually enough to last for 90 to 120 minutes of moderate exercise. The problem is an Ironman lasts a LOT longer than two hours. At some point, every athlete will run out of glycogen.

One solution is to take in more carbohydrates during the race. Ironman triathletes typically have between 60 and 70g of carbohydrate an hour during the race, in the form of sports drinks,energy gels, bars and other food. This is at the top end of what most people can absorb during exercise. However, studies have shown that exercising in the heat uses more muscle glycogen (stored carbohydrates) than exercising in the cold. But if an athlete is already getting more than 60g of carbohydrate per hour of racing, more will not help. If they can only absorb 60g per hour, then any extra will just sit in their stomach. The athlete may very well feel themselves running low on energy with a stomach full of food!

The second problem with a hot race is the increased risk of both dehydration and heat stroke. Athletes naturally drink more in the heat, but it’s easy to forget to drink often enough during a race. This is particularly deadly during an Ironman, as it makes the lack of fuel problem worse. One of the side effects of dehydration is slower stomach emptying. This means food and fluids are digested much more slowly than normal. So even if the athlete is taking in plenty of carbohydrates, they may be just sitting in the stomach rather than fuelling the muscles. What’s more, a full stomach is more likely to be an upset stomach.

So if you are racing Kona this weekend, what can you do? Well, in the days leading up to the race switch to a very high carbohydrate diet, to ensure your glycogen stores are fully stocked (this is known as carb loading). You know you’re going to sweat more than usual, so make sure you drink plenty of fluids both before and during the event to prevent dehydration. If you normally have 500mL per hour of exercise, try to get 750mL or more. It is far better to risk needing an extra pee break, than not drink enough and get heat stroke. You also lose mineral salts in sweat along with water, so swap plain water for a sports drink or water with electrolytes added.  During the event, try to take on as much carbohydrate as you can, even if you don’t feel hungry. Liquid carbohydrates provide both fluids and energy, and are usually easier on the stomach than solids, so try to get most of your carbohydrates from sports drinks and gels.

Of course, the golden rule of race nutrition is to never try anything in a race you haven’t tried in training. Hopefully none of this will be news to those towing the start line tomorrow!