Nutrition during training for the Tour du Mont Blanc - Alpine-Cols


Nutrition during training for the Tour du Mont Blanc

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Become a lean, mean, fat-burning machine!

The Tour du Mont Blanc is a sportive around the highest mountain in the Alps, starting and finishing in Les Saisies (France). The event is 338km long and includes 8,500m of climbing. To put this in context, it is almost twice the Marmotte, putting it in a class of its own. The record for the event is held by the French rider Nicolas Roux in a remarkable 11h17, corresponding to an average speed of 30km/h (including stops)! Most riders take between 14 and 17 hours. The time limit is 19h, and on average, only 60% of the starters manage to finish. 

It should be obvious that this event requires very serious preparation. In previous posts, we have analysed the event demands and proposed a training plan for the final six months (bearing in mind that, depending on your starting point, you may need as many as three years to build the required level of endurance and climbing ability). We have also suggested that mental strength is of vital importance and provided guidelines for your mental preparation.

This article addresses the third essential part of a successful ride: your nutrition plan. In this first post, we cover nutrition during the long months of training, including fuelling properly while trying to lose weight and how to convert your body to be an efficient fat-burner. In our next post, we will cover nutrition during the event itself and provide suggestions for an optimal fuelling strategy to get you through the big day.


Nutrition for endurance athletes: the basics

In order to understand our recommendations it’s important to understand a few basic facts about nutrition for endurance athletes. In this article we are going to focus on the three macronutrients carbohydrate, fat and protein since these are the variables you should be adjusting. We will provide some specific guidelines for the relative amounts of the three macronutrients, and how they should vary with your training1.

First let’s take a look at your body’s requirements. The extra calories you expend on exercise are a function of the intensity and duration of the exercise, your body weight and your metabolic efficiency. We’ll look briefly at each of these in turn. There’s an obvious link between intensity, duration and calories: just as a car consumes more fuel if you increase either the speed or the distance travelled, your body will use more fuel as you ride faster or further. Equally, a heavier car consumes more fuel, particularly when going uphill. Finally, and again we can draw the parallel to cars, efficiency is a measure of how effectively you convert the energy from food into energy delivered through your muscles, the remainder being lost as heat. The more highly trained you are, the more efficient your muscles will be and thus the less you need to eat during exercise compared to someone less efficient.

  • You will inevitably require a large amount of calories to complete the Tour du Mont Blanc.
  • You will need fewer calories, or, you will be able to ride faster for the same calories expended if: (1) you reduce your body weight, and (2) you increase your efficiency.


But where do these calories come from? In a car there’s only one fuel source. Your body, however, has two (or three if we include protein). Under all normal circumstances, including long endurance events such as the Tour du Mont Blanc, all your energy is derived from either carbohydrate or fat and most often a mixture of the two. The “mix” that your body is able to burn depends on the intensity at which you are exercising, but is highly variable from one person to the next. In one study carried out on 61 trained cyclists by the Sports Science Institute of South Africa, the researchers found that, at rest, the percentage of fat burned varied from 100% all the way down to 30%, while at steady endurance pace, (50% of VO2max), it varied from 70% down to 10%.

This is a huge variation, and the fat/carb-burning mix is of paramount importance for long events. All other things being equal, in a long endurance event the rider who burns a higher percentage of fat will always perform better than one who burns more carbs. The reason is simple: your body contains an essentially unlimited store of fat but only very limited stores of carbohydrate (in the form of glycogen), and above a certain level of intensity it is physically impossible to convert food taken during exercise fast enough if your “engine” runs predominantly on carbs. The carb-burner is thus forced to slow down, while the fat-burner can continue at the same intensity.

  • The higher percentage of fat you burn at “race pace” (typically Zone 2 at the Tour du Mont Blanc), the better you will perform.


The good news is that both efficiency and fat-burning are trainable! As renowned triathlon coach Alan Couzens shows in his blog, it is possible to convert yourself from being predominantly a carb-burner to being a fat-burner by adopting the right form of training coupled to an appropriate nutrition plan. The recommendations that follow are partly inspired by Alan’s success with professional Ironman athletes.


Nutrition while training for the Tour du Mont Blanc

Your principle nutritional goals during your training should be to:

  1. Stay healthy
  2. Provide the right amount of energy to fuel your training
  3. Achieve your optimum weight
  4. Increase your fat-burning capacity


The order of these goals is deliberate. In particular, although both weight loss and fat-burning are important goals, they must not come before either basic health or fuelling your training.


1. Stay healthy

It would be foolish to make all the efforts to train for the Tour du Mont Blanc at the expense of your health. The two traps to avoid are not eating enough of the right foods and resorting to supplements. The internet is full of promises of short-cuts and magic bullets. Don’t believe any of them. Unless advised by a doctor who understands the demands of extreme endurance events, avoid supplements and consume the widest possible variety of unprocessed, natural foods. Continuously varying your food will ensure you get all the micronutrients you need, while adjusting the absolute amounts and relative proportions of carbohydrate, fat and protein in line with your needs will help you achieve the other goals.


2. Provide the right amount of energy to fuel your training

Eat too little to fuel your training and you will soon find yourself chronically fatigued and well on the way to over-training. You may be delighted with the results on the scales as your weight comes down, but it is pointless to lose weight if you are losing your ability to perform. A hard training day can result in energy expenditure of as much as 5,000 kCal. (You can find your own data for each ride on Strava). The objective of training is to create the stimulus that will make your body adapt and become stronger, but this won’t happen if you don’t feed the machine adequately and give it what it needs.

Eat too much, on the other hand, and you may find yourself gaining weight. Don’t worry about this on hard training days, it is unlikely to happen. The biggest challenge is the rest days or recovery weeks where it is very tempting to continue eating as if you were still training heavily, in spite of needing less. Unfortunately, on these days you should cut right back and you must expect to feel a bit hungry.

Timing is important. Your body is very receptive immediately after exercise so it’s important to eat as soon as possible after you stop. If it is not convenient to have a proper meal you should at least take a snack that includes both carbs and protein, such as mixed nuts and dried fruit, a ham sandwich, or a hard-boiled egg and a couple of slices of bread. There’s also some evidence that, particularly after high intensity exercise, it may be beneficial to take a high-protein snack just before going to bed in order to promote muscle synthesis while you sleep.


3. Achieve your optimum weight

As Matt Fitzgerald says in his excellent book Racing Weight2, “the purpose of weight management for the endurance athlete is performance”. Losing weight is only a valid goal to the extent that it supports improved performance. Like practically anything else in endurance training, the key principle is slow, progressive adaptation. As a rule of thumb, it’s unwise to attempt to lose much more than 1kg of body weight per month, and you should aim at losing the majority early in the season.

If you do decide to lose weight, Fitzgerald advises against counting calories (too complicated, tedious and inaccurate) and suggests managing appetite instead. He devotes an entire chapter to the subject in his book. The key recommendations are:

  • Learn to distinguish real hunger (“belly hunger”) from desire or habit (“head hunger”), and only eat when you are experiencing belly hunger. The symptoms of belly hunger are gastric pangs and feelings of emptiness.
  • Avoid highly processed, industrial, calorie-dense, low-quality foods. If possible, avoid temptation by not letting them in your house.
  • Use smaller plates and bowls to encourage smaller portion sizes.
  • Start each meal by filling up with something that has low calorie density. This can be as simple as drinking two large glasses of water before sitting down, but also works well with thin soups or broths, raw vegetables (carrots, cucumbers, peppers) or salad.
  • Keep healthy snacks handy for when you can’t resist, such as fruit or nuts.


4. Increase your fat-burning capacity

The higher percentage of fat you burn at race pace, the better you will perform. This sounds like an argument for adopting a low-carb high-fat (LCHF) diet. Not so: the research is unequivocal on the subject. Yes, these diets are very effective at converting you to fat-burning, but no they do not help performance, on the contrary. The reason is that to perform at your best in cycling, even on an event as long as the TMB, you will have to burn a certain percentage of carbs. Unfortunately the LCHF diet significantly reduces your ability to do so. So yes, you could use a LCHF diet to prepare for and ride the TMB, but you will finish faster if you eat a more balanced diet with appropriate amounts of carbs.

So how to do it? Alan Couzens has written extensively on the topic and summarised the available research on his blog. If you want to count calories and balance your macronutrient ratios carefully, he tells you how to do it and provides some case studies. Beware, it’s complicated…

To keep things simple, here are the key recommendations, to adopt throughout your training:

  • Do the majority of your training at endurance pace, where lactate levels are low and fat-burning high.
  • Eat more carbs on days when your training is at higher intensity.
  • Cut sugar from your diet when not exercising.
  • Once a week, do a long ride fasted for the first two hours (no breakfast).
  • If you need to lose a little weight, reduce the fat in your diet.


So how much should I eat?

This is the question we all want the answer to. Unfortunately, answering it precisely requires a PhD and extensive experience in sports nutrition. There are too many variables involved and the answer will be different for the same athlete from one day to the next as their needs change.

The best approach for amateur athletes leading normal busy lives is to follow the guidelines mentioned throughout this article. To recap the most important points:

  • Eat natural, healthy foods
  • Learn to manage your appetite and adapt your food intake to your training load


Change doesn’t happen overnight. Be consistent and you can expect to see significant changes after 12-16 weeks. Start now and you should reap the benefits on July 17th!


Preparing for race day

Read How to eat more to finsh faster for detailed guidelines for what to eat and drink during the event itself. You need to prepare yourself for this during your training and, specifically, “train the gut”, while testing various options to see what works best for you.

Recent research3 has shown that performance in long endurance events can be improved by consuming up to 120g of carbohydrate per hour. This is equivalent to eating a gel, an energy bar and a banana while also drinking a full bottle of energy mix, every hour, hour after hour. If you are not used to it, this is a lot, and you need to build up progressively.

During the first part of your training you will be focused on becoming a fat-burner, with minimally fuelled long low-intensity rides.

During the last 10 weeks, we recommend progressively increasing your carb intake while training. The purpose of this is to “train the gut“. Start at 60-80g/hour and aim to reach at least 90-100g/hour throughout the ride. Your long training rides are the perfect occasion to do this. Only if you are coping well with 90-100g/hour should you try to reach 120g/hour. You’ll soon know if it isn’t working for you!

It may help to do the occasional low-intensity ride immediately after a meal, without waiting the usual 2-3 hours. For example, where earlier in your training you might skip breakfast to make a fasted ride, now you might eat a good breakfast and begin riding straight afterwards.


Final word

A successful ride at the Tour du Mont Blanc is built on the trilogy of aerobic endurance, mental strength and effective nutrition. Your nutrition plan during the long months of training should be focused first on converting your body into an efficient fat-burner, while providing adequate fuel for your training and progressively achieving your target weight. In the last ten weeks or so you should begin training the gut to accept the large quantities of carbs you will need on the day.


Next post: nutrition during the event itself and your optimal fuelling strategy for the big day.



1. Micronutrients such as vitamins and minerals are of course vital but should not be a problem so long as you obtain them naturally through eating the widest possible variety of fresh food and especially in-season fruit and vegetables.

2. Fitzgerald Matt. Racing Weight: How To Get Lean For Peak Performance. Velopress (2nd edition) 2012.

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