I just wanted to share the answer to an email that I sent to Dr. Maffetone on the issue of eating before a run or race, and during. This might make a good sticky. Here's what I wrote to him, followed by his answer:
Dear Dr. Maffetone, I just finished Eating For Endurance. Good book. I've been training with the MAF Method for 3 years (from 4:14 to 3:22 in the marathon), and this book has some solid suggestions. I couldn't find any specific advice on eating carbs before a run (how close to the start of the run) and during a run. There is a working theory that the liver glycogen must be maintained in order to maintain blood sugar so that fat can be burned and energy maintained. Many coaches recommend carbs right before the start (especially if it is an early morning workout after a nightly fast), and then throughout the workout. Personally, I've been going on the "no carbs closer than 2-3 hours" and none during a training run. In a marathon, I'll do gels after 40 minutes into the race. I have never had a bonk during a training run (up to 3.5 hours on no breakfast) and never get low on energy. I'm figuring, if I don't take carbs, my body is training itself to use fat as fuel. According to the carbs before a run theory, I am not burning fat, but muscle protein, because my liver would have run out of glycogen early in the workout, and there would be no blood sugar to ignite the fat. Hence, the bonk. But I never bonk. What does you think about this, and what are your recommendations for eating carbs before and during a run? How close to the start of a workout? How soon during a run? Should it be done during a training run? Thanks for your time and energy. --Jimmy, RI P.S. You're doing fine work as a singer/songwriter. Keep going!
*** From Phil Maffetone 7/22/08:
Dear Jimmy: Thanks for your comments, and questions, and congratulations on your running success. I’m slowly getting to a new combined edition of Training & Eating for Endurance, and your questions give me another reason to write about this important topic. The beneficial effect of carbohydrate ingestion during long training and racing is clear – it can help maintain energy, especially fat-burning. I usually don’t recommend consuming carbs during most workouts and shorter races (under 90-120 minutes), but individual variation may dictate otherwise. Those who are well trained, aerobically, and can burn relatively large amounts of fat during training and racing will not need extra fuel during most exercise. For these athletes, water is the primary need during almost all longer training and races. When more than water is needed, a carbohydrate drink is usually what I recommend (6-8% glucose; most bottled fruit juice is about this level). One can start drinking this within an hour of racing (depending on the heart rate – sooner with a higher rate), then alternate regularly with water. Experimentation during training is important. The issue of consuming carbohydrates before exercise is not so clear. Much of the confusion is probably due to a number of important issues. The first is the variation in overall health and fitness of the individual. For example, those who are well trained aerobically will burn fat for a significant source of energy, and therefore have an easier time without consuming carbs or other food before working out or racing. Another example is glucose regulation (dependant on the insulin and adrenal mechanism) – those without a problem here will generally regulate their sugar and fat burning better without a carb meal; others usually have to be very careful to time their eating, and what they eat, with training and racing. Another factor is the glycemic index and/or glycemic load of the meal consumed before exercise. Those consuming a higher glycemic meal or snack risk reducing fat burning during training or racing. This is due to the release of insulin, which inhibits fat burning. (During exercise, insulin release following carb intake is minimal and not a concern for most people.) Impairment of fat burning is especially a problem when eating within an hour or two before exercise; but any high glycemic meal, whenever it’s consumed, can inhibit fat-burning (except during activity). A moderate or low glycemic carbohydrate meal before a workout or race is usually less of problem in this regard, but then the factor to consider is whether this meal is really required (if not, avoid it). When I was younger I always worked out before my first meal of the day (only drinking water). I eventually felt better (and trained/raced with a lower heart rate) with a low glycemic snack about an hour before. The nature of the previous meal can also be a factor. The meal you consume reacts a certain way in part based on the make up of the previous one (this is sometimes called the “second-meal” effect). This may be less of a factor in the morning, but it’s significant in many people throughout the day. So, if you eat a lower glycemic meal it may react like a higher glycemic one if the previous meal was higher glycemic. The bottom line with the glycemic issue is that high glycemic foods should be avoided as they are not healthy for anyone. (The exception is liquid fruit juice during a race.) There are other factors to consider, but the most important is the individual – experimenting as objectively as possible can help determine the most effective approach. Using a heart monitor is perfect for this as any dietary changes that impact on fat-burning will usually change the heart rate, and therefore pace. Regarding your question about how close to the start of a run could you eat carbs, if you’re talking about moderate or low carb meal that depends on your comfort (in the gut) and your insulin. I know people who can run a hard 30K after a big meal, but I could never do that. So pay attention to how your gut feels; it could take 1, 2 or more hours for a meal to move out of the stomach – longer when more fat is present, less when it’s liquid. If you’re the type of person who needs to eat often, it’s important to start your run sooner after a meal. That might be a good time to make a liquid smoothie, and start your run about an hour or so later before getting hungry due to insulin’s effect (which causes the blood sugar to drop in 2 or 3 hours depending on the person – this causes hunger and reduced fat-burning). Glycogen helps maintain blood sugar, but it’s more the muscle glycogen (liver glycogen is more important to maintain blood sugar during sleep, although they work together). I’m not sure who is saying the body is using muscle protein for energy. We use mostly fat and sugar, with very small amounts of protein – so small that most physiologists ignore it during simple/basic evaluations. Larger amounts of protein will be used for energy when an athlete bonks, and this is a dangerous situation (certain amino acids convert to sugar). Unfortunately, many “theories” come from studies with unhealthy athletes (typically those who don’t burn much fat), or those who bonk – that information is then applied to the “normal” athlete. My guess is that you can still improve your marathon time, and perhaps even flirt with that 3-hour mark. Keep up the good work. Phil Maffetone
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Thanks for sharing that. I'm impressed that Dr. Maffetone took the time to reply. If I'm reading this correctly, he is of the opinion that we all have different needs in regards to this issue.
This applys to me:
"If you’re the type of person who needs to eat often, it’s important to start your run sooner after a meal."
I eat 7 times a day...3500-4000 calories to maintain my weight. I've had positive success (improved recovery and attitude) with eating the small meal before my morning runs, and will continue to do so.
All depends where you're at in your fat-burning development is the way I take it.
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Cool, huh? I've never written to an author before. Very gracious of him to get back to me.
All depends where you're at in your fat-burning development is the way I take it. The type of food you eat is important as well when eating before a run. Low-glycemic probably won't affect the fat-burning, but a couple of carbo bars might. If you're bonking in a run then you most likely need to be eating, if not then you're probably okay. Everyone has to experiment with this and see what works, adapting if need be as you get healthier and aerobically fitter.
There are other factors to consider, but the most important is the individual – experimenting as objectively as possible can help determine the most effective approach....
Great sticky, Jimmy. I love that quote from Maffetone. I have been wondering if I'm some kind of freak or something. I have always run in the morning before breakfast, and in the last year or so have consumed no carbs on any training runs. Sometimes at the end of a 15+ mile run I'll find it's been 18 hours w/o any Caloric intake, and I still feel fine. The legs don't get sore or achy if I take electrolyte capsules when it's warm. I don't get hungry (if I don't eat breakfast, I'm not hungry at luchtime.) At my annual physical, the doc told me I have an "efficient" metabolism (how do they know that?) Anyway, thanks for the great post.
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