As a coach, the questions I’m asked most (other than “How do I get faster at X”) revolve around nutrition. Some questions revolve around weight loss but most often folks just want to know what to eat in order to be stronger on the bike and avoid the dreaded “bonk”. Often the answers boil down to what, when and how much you should be eating both on and off the bike.
The Basics – Let’s start with a little bit of physiology. At very low exercise intensities the human body is a fat burning machine. We can exercise at these easy levels for very long periods of time because of an almost endless supply of energy from fat. Even in very lean individuals there can be over 50,000 calories available of stored fat in the body. But as our exercise intensity increases (like when we’re climbing on our bike) we begin to rely more and more upon carbohydrate as a fuel source, in part, because it is quicker to breakdown than fat. Unfortunately, we can only store about 1,500-2,000 calories of carbohydrate (stored as glycogen) in the body. This may sound like a lot until you realize that you can easily burn 600+ calories an hour riding at higher intensities. Ride hard enough, long enough and the body begins to run out causing us to hit the wall. This is our body forcing us to slow down because it must now rely upon fat which is slower to metabolize.
Before – The best case scenario is to be eating 3hrs prior to the start of your ride or event. This can be tough if you plan on being on your bike at 7 or 8am. So, the general rule of thumb is to eat 1g of carbohydrate for every 2lbs of body weight per hour prior to exercise. Put simply, take your weight and divide it in half then eat that many grams of carbs for each hour you have before the start. For example, a 100lb person would eat 50g of carbs an hour before exercise, 100g if they were eating 2hrs before and 150g 3hrs before. This is to allow the body enough time to digest prior to exercise. I recommend a mix of both simple (fruit juices, honey, etc.) and complex (whole grains, oats, etc.) carbs as well as some protein and fat in this pre-event meal.
During – Feeding during a ride is largely based upon intensity. For low-intensity rides there is no real need to eat since we’re burning mainly fat (remember we have a ton of it to keep us going). A big mistake I see a lot of riders make is that they’re eating even on short, easy rides. One of the biggest adaptions we’re looking for through aerobic training is a greater reliance upon fat as a fuel source. If we’re eating during an easy ride our body becomes lazy and uses the food we’re consuming because it’s easier to get at than stored fat.
As we increase our intensity, and our reliance upon glycogen, we need to start thinking about feeding to keep up with energy demands. Unfortunately, demand can outpace digestion as we shift blood away from the digestive tract towards working muscle. On really long or high intensity days it’s important to feed from the start and steadily throughout the ride. For women, the maximum amount they’ll typically be able to eat AND digest is about 250-300 calories an hour, 300-350 calories for men. This can be from a mix of gels, bars, beverages etc. Make sure to spread the calories out over the hour instead of all at one time. Remember, the higher the intensity the less we can digest so try to feed during the easier sections of the ride such as downhill or when it’s flat. If you’re working hard going uphill odds are that bar you just ate is just going to sit in your stomach and that’s not a good feeling.
After – The sooner the better but try to eat at least within 2 hours of finishing your ride, this is when cells are most susceptible to taking on nutrients. The biggest thing to focus on is carbs, we need to replenish all of that glycogen we just burned. We also need a little bit of protein to help repair muscle tissue. It’s also ok to eat something sugary after your ride. Don’t worry, I won’t tell anyone. A spike in your blood sugar, and the corresponding insulin response, actually helps to bring nutrients into cells.
Practice Makes Perfect – Just as you would practice your climbing or bike handling, nutrition is a skill best learned through repetition. Use your training rides to practice the timing and amount you are eating as well as what you are eating.
Don’t Try Anything New on Event Day – This phrase could be extended to many facets of riding (shorts, saddles, shoes etc.) but has the biggest implications when it comes to nutrition. Riders will spend months eating the same things during their rides because that is what works for them and their stomachs can handle it. Suddenly, on event day, they’re eating everything available at the aid stations. For some this is ok, for others it is a recipe for GI distress.