Question of the month: Should I eat on my longer spring base rides?
Mark Shorter Our bodies constantly use fat as an energy source, we don't have to train our bodies to do so. However it is possible to train our guts to process more calories by consuming more calories when working out and this can pay off in spades come race season.
Jeremy Howard This is a possibility and could be beneficial, though I'm not sure there's a ton of research to support that. I also know you need to keep the effort really low (low to mid zone 1) for a long time and build in very slowly to high zone 1 max. If you do this refueling immediately and frequently post-ride with lots of carbs is an absolute necessity. This is super high stress on the system though if you're going long. Personally I wouldn't advise until there is more research that supports this method as a great option. I think you can achieve much of that adaptation, with lower stress, by going calorie free in shorter rides, up to two hours, and maintain some level of carb intake during longer rides.
Lance Watson A link I posted the other day: Many trends in nutrition over the 30 years I have coached. It always comes back around to Carbohydrates.
This is a good basic look at some different sugars and contemplates fat as fuel. A good introductory article for athletes who may have questions.
Chuck Kemeny I believe in the body's ability to adapt. Whether it is adapting to efficiently burn fats or targeting higher calories, fluid ounces, or carbohydrates. If you train your body intelligently for a specific adaptation, it can certainly do it in time. In my experience, the adaptation to fat as the primary fuel source takes much longer than adapting to sugars or carbohydrates.
Christopher Thomas I'm a big believer that everyone is different and one approach is NOT going to be the answer for every athlete. I, personally, have a sensitive gut and over the years I have found that when I race IM distance I just cannot tolerate the prescribed carbs/hour. So, I started experimenting with the fasting, higher fat approach several years ago. I found that it does take a lot of time to adjust, but there is no doubt that I am much more efficient now and I can do 2-4 hour Zone 1-2 rides on just water. Where I used to bonk around the 1.5-1.75 hour mark. I have raced Kona on 100 calories an hour and I've raced on 400 calories an hour. My best result came the year that I used 200 calories an hour which consisted of UCAN and Nuun. It was the 1st time that I was able to avoid GI issues and cramping later in the bike. Now I know what science says, but this worked for me. It's kind of like what Macca talked about in his book, he did all that testing on what was optimal nutrition but resorted to cola on the bike because it was the only thing that settled his gut down and he ended up doing pretty well. I know this is not the approach for everyone, but I think we need to be aware that this can work for some if practiced properly and as Chuck says, the body adapts.
Celine Evans This topic is highly debated however, based on current evidenced based research I am not convinced that the LCHF is the best option for optimal performance in endurance athletes. We all know that our muscles use carbs and fat as fuel sources in endurance exercise; the higher the intensity, the higher the percentage of carbohydrate used. The ‘fat adapted’ athletes were found to perform the slowest of the three groups in the Supernova study, indicating the least training adaptation from training. L. Burke et al (2016) confirmed the LCHF diet increases oxygen demand, in other words reducing energy economy.
I have worked with athletes on a ‘periodized’ plan where we ensure there is adequate carb availability for key training sessions where the athlete ‘trains hard’ and the carbohydrates are needed in order to maximize performance and ‘quality’ as the main priority. For those with more sensitive GI tracts there is evidence that mouth rinses with fluids and foods can be used in events to maximize performance with reduced load for the gut. Other less intense sessions in the week could be to ‘train smart’ on lower carbohydrate availability with the primary goal of maximizing cellular adaptations. An example of this is having a lower carb dinner the night before the ‘train smart’ session. The ‘training low’ is subjective for many and if not followed correctly can lead to inadequate adaptation, potential illness and reduced performance. What can occur in advertently is low energy availability; which means the athlete is not meeting their physiological needs for daily function in addition to training. Strategic timing of carbs in regards to training sessions is essential for the desired outcomes. Every athlete is unique with regard to their nutritional needs and nutrition plans need to be personalized to account for their event, performance goals, challenges while catering to their food preferences. This can be modified further based on their individual responses in training, racing and specific conditions.
Refer to the article below by A. Jeukendrup who walks you through the two theories:
The periodized plan in the diagram helps depict its effectiveness in training adaptation.
Dan Smith From what I gather, low carb training had some effect on fat oxidation but has a greater effect on building the mitochondria in muscles. However it's widely known that fast marathoners and Ironman age group winners are all burning 90% or more carbs during a race for energy. There has been other theories regarding LCHF during training but with elite athletes EVERYTHING is highly monitored and controlled. Some of the top guys have been doing this for 5-10 years to get where they are now. It's not something that can be done in 6-12 months by an age group athlete who has an unrestricted diet and whose workouts are often dictated by a time frame outside of their control.