The rest days during the Tour de France are a chance for riders to gather their thoughts, replenish their energy, and look forward to the racing yet to come. For the most part, riders stick to routines they have developed over years of racing. There is a rhythm to stage racing, and it’s best not to disturb it.

Since the body is accustomed to hours in the saddle, the riders go on about a three-hour ride on the rest day. While the intensity is lower than racing, it is also not merely a recovery ride. The key to racing well the day after a Tour de France rest day is to keep the body going. Riders would gladly take a day of complete rest, but they would pay a hefty price for it during Tuesday’s grueling Stage 15. Too little activity on the rest day often leads to heavy and sluggish legs the following day, and that would be a recipe for disaster when the route to the finish includes the Col d’Izoard, the Col du Lautaret, and, of course, the 21 fabled switchbacks of L’Alpe d’Huez.

I’ve received a lot of questions regarding the riders’ diets during the Tour de France, so I thought I would spend the rest day talking about nutrition. The main dietary goals during the Tour are fueling and recovery, and a rider’s diet significantly impacts his performance.

strongThe Tour de France Diet
During the Tour de France, riders consume an average of 6,000 to 7,000 calories a day, more on particularly long or hard days. Some of these calories are eaten during sit-down meals: breakfast, a pre-race meal, and dinner. The rest are consumed on the bike during the stage or through snacking in between meals. No matter the time of day, it is rare to see a Tour de France rider without either food or drink in his hand.

Riders aim to get about 70 percent of their calories from carbohydrates (CHO), 15 percent from protein, and 15 percent from fat. While endurance athletes burn a mixture of all three macronutrients for energy while riding, CHO is primary fuel for aerobic performance. When a rider is well below his lactate threshold, the energy coming from CHO and fat is somewhat balanced, but as the intensity increases and his aerobic engine can’t supply energy fast enough to meet the rising demand, the anaerobic energy system kicks in to fill the gap. Since this energy system primarily burns carbohydrate, the percentage of total energy coming from CHO increases as well.

The body can store fat very well, and even extremely lean riders have plenty of fat to use for fuel. In contrast, there is a limit to the amount of CHO you can store in muscles and in the liver: about 1,600 to 1,800 calories. Since this is only enough fuel for a few hours of riding, it is essential that riders ingest CHO during and between stages.

The importance of carbohydrate cannot be overstated. Not only is it the primary fuel source for endurance performance, it is the only fuel the brain and central nervous system can use. The brain cannot produce energy from fat or protein on its own, it can only take glucose (sugar) from the blood. This is part of the reason bonking (running low on blood sugar) is so detrimental to performance. The confusion, nausea, and disorientation that go along with bonking are more due to the brain running low on glucose than a problem with energy-starved muscles. When push comes to shove, the brain acts defensively to make sure it gets enough fuel. It forces you to slow down or stop exercising so it can use what sugar you have left to maintain your basic bodily functions.

Protein is also an important nutrient for endurance athletes. Riders derive 10-15 percent of their energy from protein, and it is also essential for tissue repair and immune system health. Since tissues are the main storage form of protein, riders have to make sure they ingest enough to prevent the body from breaking down muscle or connective tissue for energy, cellular repair, or the immune system.

What Riders Eat
It is hard work consuming upwards of 6,000 calories a day, so cyclists try to eat foods that are rich in calories and nutrients. During breakfast and dinner, they get their carbohydrates from potatoes, rice, pasta, cereal, whole grain breads, and fruits and vegetables. Protein sources include eggs, meat, chicken, and yogurt. Their fat intake is usually the result of the way their meals are prepared. Willy, the Discovery Channel team’s chef, uses monounsaturated oils when he cooks, such as olive oil, and the team consumes some butter and cheese with meals as well.

On the bike, riders eat a mixture of energy bars, gels, pastries, sandwiches, fruit, and other foods. The soigneurs prepare musette bags with small sandwiches, often ham or turkey and cheese with butter on a roll, and some directors like to save the sweeter pastries until later in races. As strange as it sounds, a sweet treat still lifts people’s spirits, even tough guys in the Tour de France.

Riders aim to ingest 250 to 350-plus calories per hour while racing. While some of this comes from the aforementioned foods, the rest comes from sports drinks. With the extremely hot weather in the Tour this year, riders are drinking between two to three bottles per hour on the bike, and it is important for about half of that fluid to be sports drink. Not only do sports drinks provide CHO, they are also an important source of electrolytes.

The central nervous system (CNS) controls every nerve impulse in the body, and needs sodium, potassium, and calcium to conduct electrical signals that contract muscles and run all bodily functions. You lose a lot of electrolytes through sweat, as evidenced by the white crusty residue on riders’ jerseys and helmet straps. (A mildly disgusting way to prove this to yourself is to lick your helmet strap. What you taste is almost entirely salt.) To prevent muscle cramps and more severe CNS consequences from losing too many electrolytes, riders try to make sure at least one of every three bottles they drink contains sports drink.

PowerBar recognized that endurance athletes need more sodium and reformulated their Endurance energy drink and PowerBar Gels to include more sodium per serving. At the same time, they also changed the mixture of sugars in these products to a 2:1 ratio of maltodextrin (glucose) and fructose. New research has shown that this mixture increases the amount of carbohydrate an athlete can take in and use, from one gram per minute to 1.3 to1.4 grams per minute. At four calories per gram, over the course of an hour this means a rider in the Tour can benefit from 312 to 336 calories of carbohydrate energy instead of only 240.

When Riders Eat
When a rider eats also influences performance. When they wake up, they have effectively undergone an eight- to ten-hour fast, so breakfast is an important start to the day. Since Tour de France stages typically begin in the late morning or early afternoon, the riders also eat a pre-race meal about three hours before the start. This meal is almost entirely carbohydrate. In between the pre-race meal and the start, riders continue grazing on bars and fruit and they are almost never without a water bottle. Riders continue eating as soon as the stage begins and take small bits of food every 10 to 15 minutes.

Immediately following the stage, riders are handed another musette bag containing more food and bottles. The big difference is that these post-stage bottles usually contain a recovery-oriented drink with a lot of carbohydrate and a little protein. The body is most efficient at replenishing CHO stores in the first 60 minutes after exercise, and a little bit of protein in the drink helps muscles absorb CHO from the bloodstream. The riders continue working on recovery in the team bus; the Discovery Channel bus, for instance, is equipped with blenders so they can make smoothies on the way back to the hotel.

A Tour Rider Travels On His Stomach
Poor nutrition or any sort of stomach problem causes serious problems for Tour de France competitors. The energy and hydration demands of the event are so huge that even a slight caloric or fluid deficit spells big trouble. Learning proper nutritional and recovery habits is part of the learning process riders go through on their way to becoming successful Tour de France riders. Younger and less experienced riders run into trouble because they get behind in their nutrition or hydration, and it is nearly impossible to catch back up. Like Napoleon said of great armies, the Tour de France marches on its stomach.

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The Tour Marches On Its Stomach